IPv4

Inter-AS : Carrier Supporting Carrier on Nokia (Part IV)

In Inter-AS, we saw how the VPN customers can communicate to each other while connecting to different ISPs. Some VPN customers are service providers who further offer services (VPN/Internet) to their end customers.

The network provider provides an MPLS VPN backbone to the customer carrier.

The customer carrier provides VPN or Internet services to its end customers.

This is why it is also known as carrier’s carrier or carrier serving carrier. It supports 2 scenarios:

  • Customer carrier provides VPN services to end customers via a common VPN provided by network provider.
  • Customer carrier exchanges full internet routes via  common VPN provided by network provider.

CSC- Network Provider

The network provider provides MPLS backbone to the customer carrier. The PE’s are configured with CSC VPRN to provide the connectivity between customer carrier sites. The network provider PE routers are referred to as CSC-PE to differentiate them from customer carrier PE routers.

CSC-Customer Carrier

Customer carrier interconnect via Network provider CSC VPRN to its sites. The customer carrier CE routers are referred as CSC-CE to differentiate them from CE routers of end customers.

Customer carrier can be:

  • ISP which provides Internet services.
  • MPLS SP which provides  Layer2 and Layer3 services to end customers (VPN).

In this post, we will discuss both flavors of customer carrier.

CSC- VPRN SP Customer Carrier

If customer carrier is a MPLS service provider providing VPN services to end customer:

  • Customer carrier has to be configured with VRF for the end customer and end-customer traffic will be transported over this new service.
  • Customer carrier has to be MPLS enabled.
  • Customer carrier PE routers in different sites must run MP-iBGP to exchange VPN routes. This will create a transport tunnel between the Pes.

Control Plane:

  • PE in AS200 advertise their system IP to CSC-CE via IGP/LDP or BGP for route and label exchange.
  • eBGP is established between CSC-CE and CSC-PE to exchange labeled IPv4 routes of PE routers.
  • MP-iBGP session between CSC-PE’s within the network provider network is used to advertise the PE routes as VPNv4 routes which will be further advertised by CSC-PE-2 to the Site 2 of customer carrier.
  • This will provide connectivity between PE routers on different customer carrier sites and a transport tunnel will be established between them.
  • CSC-CE to CSC-PE can use either LDP or BGP for label distribution. However, Nokia 7×50 SR only supports BGP.

“carrier-carrier-vpn” command is used to configure the VPRN as CSC. CSC VPRN can only have IP/MPLS interface of network type; SAP and spoke-sdp aren’t allowed.

“Network-interface” command is use to create network-type interface under csc vpn.

Below is the topology we are going to use:

Configuration:

Network Provider Prelim Config:

CSC-PE3:

router Base
        interface "system"
            address 10.10.10.3/32
            no shutdown
        exit
        interface "toR4"
            address 10.3.4.3/27
            port 1/1/1
            no shutdown
        exit
        autonomous-system 100
ospf 0
            area 0.0.0.0
                interface "system"
                    no shutdown
                exit
                interface "toR4"
                    interface-type point-to-point
                    no shutdown
                exit
            exit
            no shutdown
        exit
ldp
            interface-parameters
                interface "toR4"
Exit
bgp
            group "MP-iBGP"
                neighbor 10.10.10.4
                    family vpn-ipv4
                    peer-as 100
                exit
            exit
            no shutdown
        exit
    exit

CSC-PE4:

router Base
        interface "system"
            address 10.10.10.4/32
            no shutdown
        exit
        interface "toR3"
            address 10.3.4.4/27
            port 1/1/1
            no shutdown
        exit
        autonomous-system 100
 ospf 0
            area 0.0.0.0
                interface "system"
                    no shutdown
                exit
                interface "toR3"
                    interface-type point-to-point
                    no shutdown
                exit
            exit
            no shutdown
        exit
ldp
            interface-parameters
                interface "toR3"
Exit
bgp
            group "MP-iBGP"
                neighbor 10.10.10.3
                    family vpn-ipv4
                    peer-as 100
                exit
            exit
            no shutdown
        exit
    exit

Customer-Carrier Prelim Config:

CSC-CE1:

router Base
        interface "system"
            address 10.10.10.1/32
            no shutdown
        exit
        interface "toR3"
            address 10.1.3.1/27
            port 1/1/3
            no shutdown
        exit
        interface "toR6"
            address 10.1.6.1/27
            port 1/1/2
            no shutdown
        exit
        autonomous-system 200
ospf 0
            area 0.0.0.0
                interface "system"
                    no shutdown
                exit
                interface "toR6"
                    interface-type point-to-point
                    no shutdown
                exit
            exit
            no shutdown
        exit
ldp
            interface-parameters
                interface "toR6"
Exit
PE-6:

router Base
        interface "system"
            address 10.10.10.6/32
            no shutdown
        exit
        interface "toR1"
            address 10.1.6.6/27
            port 1/1/2
            no shutdown
        exit
        autonomous-system 200
ospf 0
            area 0.0.0.0
                interface "system"
                    no shutdown
                exit
                interface "toR1"
                    interface-type point-to-point
                    no shutdown
                exit
            exit
            no shutdown
        exit
ldp
            interface-parameters
                interface "toR1"
Exit
service
        customer 1 create
            description "Default customer"
        exit
        ies 10 customer 1 create
            interface "ies-10-toCE" create
            exit
        exit
        vprn 20 customer 1 create
            interface "vprn-20-toCE" create
            exit
        exit
        ies 10 customer 1 create
            description "SiteA"
            interface "ies-10-toCE" create
                address 100.6.6.6/24
                loopback
            exit
            no shutdown
        exit
        vprn 20 customer 1 create
            description "SiteA"
            router-id 10.10.10.6
            autonomous-system 200
            route-distinguisher 200:20
            auto-bind-tunnel
                resolution-filter
                    ldp
                exit
                resolution filter
            exit
            vrf-target target:200:20
            interface "vprn-20-toCE" create
                address 200.6.6.6/24
                loopback
            exit
            no shutdown
        exit
    exit
CSC-CE2:

router Base
        interface "system"
            address 10.10.10.2/32
            no shutdown
        exit
        interface "toR4"
            address 10.2.4.2/27
            port 1/1/3
            no shutdown
        exit
        interface "toR5"
            address 10.2.5.2/27
            port 1/1/2
            no shutdown
        exit
        autonomous-system 200
ospf 0
            area 0.0.0.0
                interface "system"
                    no shutdown
                exit
                interface "toR5"
                    interface-type point-to-point
                    no shutdown
                exit
            exit
            no shutdown
        exit
ldp
            interface-parameters
                interface "toR5"
Exit
PE-5:

router Base
        interface "system"
            address 10.10.10.5/32
            no shutdown
        exit
        interface "toR2"
            address 10.2.5.5/27
            port 1/1/2
            no shutdown
        exit
        autonomous-system 200
ospf 0
            area 0.0.0.0
                interface "system"
                    no shutdown
                exit
                interface "toR2"
                    interface-type point-to-point
                    no shutdown
                exit
            exit
            no shutdown
        exit
ldp
            interface-parameters
                interface "toR2"
Exit
service
        customer 1 create
            description "Default customer"
        exit
        ies 10 customer 1 create
            interface "ies-10-toCE" create
            exit
        exit
        vprn 20 customer 1 create
            interface "vprn-20-toCE" create
            exit
        exit
        ies 10 customer 1 create
            description "SiteB"
            interface "ies-10-toCE" create
                address 100.5.5.5/24
                loopback
            exit
            no shutdown
        exit
        vprn 20 customer 1 create
            description "SiteB"
            router-id 10.10.10.5
            autonomous-system 200
            route-distinguisher 200:20
            auto-bind-tunnel
                resolution-filter
                    ldp
                exit
                resolution filter
            exit
            vrf-target target:200:20
            interface "vprn-20-toCE" create
                address 200.5.5.5/24
                loopback
            exit
            no shutdown
        exit
    exit

CSC Configuration:

  • Configure CSC VPRN on CSC-PE3 and CSC-PE4
CSC-PE3:

Configure port 1/1/3
Shutdown
Ethernet mode network
No shutdown
Exit
 
service
        customer 1 create
            description "Default customer"
        exit
        customer 30 create
            description "CSC"
        exit
        vprn 30 customer 30 create
            carrier-carrier-vpn
        exit
        vprn 30 customer 30 create
            carrier-carrier-vpn
            autonomous-system 100
            route-distinguisher 100:30
            auto-bind-tunnel
                resolution-filter
                    ldp
                exit
                resolution filter
            exit
            vrf-target target:100:30
            network-interface "toCSCCE1" create
                address 10.1.3.3/27
                port 1/1/3
                no shutdown
            exit
           no shutdown
        exit
    exit
CSC-PE4:

Configure port 1/1/3
Shutdown
Ethernet mode network
No shutdown
Exit
 
service
        customer 1 create
            description "Default customer"
        exit
        customer 30 create
            description "CSC"
        exit
        vprn 30 customer 30 create
            carrier-carrier-vpn
        exit
        vprn 30 customer 30 create
            carrier-carrier-vpn
            autonomous-system 100
            route-distinguisher 100:30
            auto-bind-tunnel
                resolution-filter
                    ldp
                exit
                resolution filter
            exit
            vrf-target target:100:30
            network-interface "toCSCCE2" create
                address 10.2.4.4/27
                port 1/1/3
                no shutdown
            exit
            no shutdown
        exit
    exit
  • Configure eBGP session between CSC-CE1 and CSC-PE3 / CSC-CE2 and CSC-PE4. Advertise only the system IP to ebgp peer and enable the advertisement of labeled routes.
CSC-CE1:

configure router Bgp
group "toCSC"
                family ipv4
                loop-detect off
                export "AdvSystemIP"
                peer-as 100
                neighbor 10.1.3.3
                    advertise-label ipv4
                exit
            exit
            no shutdown
        exit
    exit
policy-options
            begin
            prefix-list "SystemIP"
                prefix 10.10.10.6/32 exact
            exit
policy-statement "AdvSystemIP"
                entry 10
                    from
                        prefix-list "SystemIP"
                    exit
                    to
                        protocol bgp
                    exit
                    action accept
                    exit
                exit
                default-action reject
            exit
            commit
        exit
CSC-PE4:

vprn 30
         bgp
                group "toCSCCE"
                    family ipv4
                    export "AdvSite1"
                    peer-as 200
                    neighbor 10.2.4.2
                        advertise-label ipv4
                    exit
                exit
                no shutdown
            exit
 
policy-options
            begin
            prefix-list "Site1Prefix"
                prefix 10.10.10.6/32 exact
            exit
            policy-statement "AdvSite1"
                entry 10
                    from
                        protocol bgp-vpn
                        prefix-list "Site1Prefix"
                    exit
                    action accept
                    exit
                exit
                default-action reject
            exit
            commit
        exit
CSC-PE3:

vprn 30
      bgp
                group "toCSCCE"
                    family ipv4
                    export "AdvSite2"
                    peer-as 200
                    neighbor 10.1.3.1
                        advertise-label ipv4
                    exit
                exit
                no shutdown
            exit
 
policy-options
            begin
            prefix-list "Site2prefix"
                prefix 10.10.10.5/32 exact
            exit
            policy-statement "AdvSite2"
                entry 10
                    from
                        protocol bgp-vpn
                        prefix-list "Site2prefix"
                    exit
                    action accept
                    exit
                exit
                default-action reject
            exit
            commit
        exit
CSC-CE2:

Bgp
     group "toCSC"
                family ipv4
                loop-detect off
                export "AdvSystemIP"
                peer-as 100
                neighbor 10.2.4.4
                    advertise-label ipv4
                exit
            exit
            no shutdown
        exit
   
policy-options
            begin
            prefix-list "SystemIP"
                prefix 10.10.10.5/32 exact
            exit
policy-statement "AdvSystemIP"
                entry 10
                    from
                        prefix-list "SystemIP"
                    exit
                    to
                        protocol bgp
                    exit
                    action accept
                    exit
                exit
                default-action reject
            exit
            commit
        exit
  • CSC-CE1 and CSC-CE2 are configured to advertise only system IP of local PE routers.
  • CSC-PE3 and CSC-PE4 are configure to advertise only the system IP of remote site received via MP-BGP peer.
  • “loop-detect” is turned off on CSC-CE routers as the routers in different side belong to same customer carrier AS.
  • Verify that BGP is up and CSC-CE routers now have system IP of PE routers from different site.
 *A:CSC-PE3# show router 30 bgp summary 
===============================================================================
 BGP Router ID:10.10.10.3       AS:100         Local AS:100       
===============================================================================
BGP Admin State         : Up          BGP Oper State              : Up
Total Peer Groups       : 1           Total Peers                 : 1        
Total BGP Paths         : 5           Total Path Memory           : 1032     
Total IPv4 Remote Rts   : 1           Total IPv4 Rem. Active Rts  : 1        
Total McIPv4 Remote Rts : 0           Total McIPv4 Rem. Active Rts: 0        
Total McIPv6 Remote Rts : 0           Total McIPv6 Rem. Active Rts: 0        
Total IPv6 Remote Rts   : 0           Total IPv6 Rem. Active Rts  : 0        
Total IPv4 Backup Rts   : 0           Total IPv6 Backup Rts       : 0        
 
Total Supressed Rts     : 0           Total Hist. Rts             : 0        
Total Decay Rts         : 0        
 
Total FlowIpv4 Rem Rts  : 0           Total FlowIpv4 Rem Act Rts  : 0        
Total FlowIpv6 Rem Rts  : 0           Total FlowIpv6 Rem Act Rts  : 0        
 
===============================================================================
BGP Summary
===============================================================================
Legend : D - Dynamic Neighbor
===============================================================================
Neighbor
Description
                   AS PktRcvd InQ  Up/Down   State|Rcv/Act/Sent (Addr Family)
                      PktSent OutQ
-------------------------------------------------------------------------------
10.1.3.1
                200       177    0 01h25m02s 1/1/1 (IPv4)
                          179    0          
-------------------------------------------------------------------------------
*A:CSC-PE3# 
 

*A:CSC-CE1# show router route-table
 
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags]                            Type    Proto     Age        Pref
      Next Hop[Interface Name]                                    Metric  
-------------------------------------------------------------------------------
10.1.3.0/27                                   Local   Local     22h18m17s  0
       toR3                                                         0
10.1.6.0/27                                   Local   Local     22h18m17s  0
       toR6                                                         0
10.10.10.1/32                                 Local   Local     22h18m28s  0
       system                                                       0
10.10.10.5/32                                 Remote  BGP       00h57m19s  170
       10.1.3.3                                                     0
10.10.10.6/32                                 Remote  OSPF      22h18m06s  10
       10.1.6.6                                                     100
-------------------------------------------------------------------------------
No. of Routes: 5
  • Configure iBGP between PE6 and CSC-CE1 / PE5 and CSC-CE2. Advertise labeled IPv4 routes and only the system Ips received from ebgp peer.
 PE-6:
   bgp
            group "iBGP"
                family ipv4
                loop-detect off
                peer-as 200
                neighbor 10.10.10.1
                    loop-detect off
                    advertise-label ipv4
                exit
            exit
           no shutdown
        exit
CSC-CE1:

bgp
            group "iBGP"
                family ipv4
                loop-detect off
                export "AdvSite2"
                peer-as 200
                neighbor 10.10.10.6
                    advertise-label ipv4
                exit
            exit
            no shutdown
        exit
   
policy-options
            begin
          prefix-list "Site2prefix"
                prefix 10.10.10.5/32 exact
            exit
            policy-statement "AdvSite2"
                entry 10
                    from
                        prefix-list "Site2prefix"
                    exit
                    action accept
                    exit
                exit
                default-action reject
            exit
          commit
        exit

PE-5:
bgp
            group "iBGP"
                family ipv4
                loop-detect off
                peer-as 200
                neighbor 10.10.10.2
             loop-detect off        

advertise-label ipv4
                exit
            exit
           no shutdown
        exit
CSC-CE2:

bgp
            group "iBGP"
                family ipv4
                loop-detect off
                export "AdvSite1"
                peer-as 200
                neighbor 10.10.10.5
                    advertise-label ipv4
                exit
            exit
            no shutdown
        exit
 
policy-options
            begin
            prefix-list "Site1Prefix"
                prefix 10.10.10.6/32 exact
            exit
            policy-statement "AdvSite1"
                entry 10
                    from
                        prefix-list "Site1Prefix"
                    exit
                    action accept
                    exit
                exit
                default-action reject
            exit
           commit
        exit
  • Verify the BGP state and now PE routers in different sites should be able to reach each other.
*A:CSC-CE1# show router bgp summary 
===============================================================================
 BGP Router ID:10.10.10.1       AS:200         Local AS:200       
===============================================================================
BGP Admin State         : Up          BGP Oper State              : Up
Total Peer Groups       : 2           Total Peers                 : 2        
Total BGP Paths         : 6           Total Path Memory           : 1224     
Total IPv4 Remote Rts   : 1           Total IPv4 Rem. Active Rts  : 1        
Total McIPv4 Remote Rts : 0           Total McIPv4 Rem. Active Rts: 0        
Total McIPv6 Remote Rts : 0           Total McIPv6 Rem. Active Rts: 0        
Total IPv6 Remote Rts   : 0           Total IPv6 Rem. Active Rts  : 0        
Total IPv4 Backup Rts   : 0           Total IPv6 Backup Rts       : 0        
 
Total Supressed Rts     : 0           Total Hist. Rts             : 0        
Total Decay Rts         : 0        
 
Total VPN Peer Groups   : 0           Total VPN Peers             : 0        
Total VPN Local Rts     : 0        
Total VPN-IPv4 Rem. Rts : 0           Total VPN-IPv4 Rem. Act. Rts: 0        
Total VPN-IPv6 Rem. Rts : 0           Total VPN-IPv6 Rem. Act. Rts: 0        
Total VPN-IPv4 Bkup Rts : 0           Total VPN-IPv6 Bkup Rts     : 0        
 
Total VPN Supp. Rts     : 0           Total VPN Hist. Rts         : 0        
Total VPN Decay Rts     : 0          
 
Total L2-VPN Rem. Rts   : 0           Total L2VPN Rem. Act. Rts   : 0        
Total MVPN-IPv4 Rem Rts : 0           Total MVPN-IPv4 Rem Act Rts : 0        
Total MDT-SAFI Rem Rts  : 0           Total MDT-SAFI Rem Act Rts  : 0        
Total MSPW Rem Rts      : 0           Total MSPW Rem Act Rts      : 0        
Total RouteTgt Rem Rts  : 0           Total RouteTgt Rem Act Rts  : 0        
Total McVpnIPv4 Rem Rts : 0           Total McVpnIPv4 Rem Act Rts : 0        
Total MVPN-IPv6 Rem Rts : 0           Total MVPN-IPv6 Rem Act Rts : 0        
Total EVPN Rem Rts      : 0           Total EVPN Rem Act Rts      : 0        
Total FlowIpv4 Rem Rts  : 0           Total FlowIpv4 Rem Act Rts  : 0        
Total FlowIpv6 Rem Rts  : 0           Total FlowIpv6 Rem Act Rts  : 0        
 
===============================================================================
BGP Summary
===============================================================================
Legend : D - Dynamic Neighbor
===============================================================================
Neighbor
Description
                   AS PktRcvd InQ  Up/Down   State|Rcv/Act/Sent (Addr Family)
                      PktSent OutQ
-------------------------------------------------------------------------------
10.1.3.3                             
                100       176    0 01h24m37s 1/1/1 (IPv4)
                          179    0          
10.10.10.6
                200       166    0 01h18m28s 0/0/1 (IPv4)
                          168    0          
-------------------------------------------------------------------------------
 
*A:PE6# show router route-table
 
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags]                            Type    Proto     Age        Pref
      Next Hop[Interface Name]                                    Metric  
-------------------------------------------------------------------------------
10.1.6.0/27                                   Local   Local     22h19m52s  0
       toR1                                                         0
10.10.10.1/32                                 Remote  OSPF      22h19m51s  10
       10.1.6.1                                                     100
10.10.10.5/32                                 Remote  BGP       00h58m24s  170
       10.10.10.1 (tunneled)                                        0
10.10.10.6/32                                 Local   Local     22h20m20s  0
       system                                                       0
100.6.6.0/24                                  Local   Local     22h20m20s  0
       ies-10-toCE                                                  0
-------------------------------------------------------------------------------
No. of Routes: 5
 
*A:PE6# ping 10.10.10.5 source 10.10.10.6
PING 10.10.10.5 56 data bytes
64 bytes from 10.10.10.5: icmp_seq=1 ttl=64 time=9.43ms.
64 bytes from 10.10.10.5: icmp_seq=2 ttl=64 time=7.71ms.
64 bytes from 10.10.10.5: icmp_seq=3 ttl=64 time=9.44ms.
64 bytes from 10.10.10.5: icmp_seq=4 ttl=64 time=8.71ms.
64 bytes from 10.10.10.5: icmp_seq=5 ttl=64 time=9.91ms.
 
---- 10.10.10.5 PING Statistics ----
5 packets transmitted, 5 packets received, 0.00% packet loss
round-trip min = 7.71ms, avg = 9.04ms, max = 9.91ms, stddev = 0.768ms
*A:PE6#
  • Configure MP-iBGP between PE-5 and PE-6 to exchange the VPNv4 routes.
PE-6
Bgp
     group "MPBGP"
                family vpn-ipv4
                peer-as 200
                neighbor 10.10.10.5
                exit
            exit
            no shutdown
        exit
PE-5 
Bgp  
    group "MPBGP"
                family vpn-ipv4
                peer-as 200
                neighbor 10.10.10.6
                exit
            exit
            no shutdown
        exit
  • Verify the BGP state and the routes received in VPRN:
 *A:PE6# show router bgp summary 
===============================================================================
 BGP Router ID:10.10.10.6       AS:200         Local AS:200       
===============================================================================
BGP Admin State         : Up          BGP Oper State              : Up
Total Peer Groups       : 2           Total Peers                 : 2        
Total BGP Paths         : 11          Total Path Memory           : 2248     
Total IPv4 Remote Rts   : 1           Total IPv4 Rem. Active Rts  : 1        
Total McIPv4 Remote Rts : 0           Total McIPv4 Rem. Active Rts: 0        
Total McIPv6 Remote Rts : 0           Total McIPv6 Rem. Active Rts: 0        
Total IPv6 Remote Rts   : 0           Total IPv6 Rem. Active Rts  : 0        
Total IPv4 Backup Rts   : 0           Total IPv6 Backup Rts       : 0        
 
Total Supressed Rts     : 0           Total Hist. Rts             : 0        
Total Decay Rts         : 0        
 
Total VPN Peer Groups   : 0           Total VPN Peers             : 0        
Total VPN Local Rts     : 2        
Total VPN-IPv4 Rem. Rts : 1           Total VPN-IPv4 Rem. Act. Rts: 1        
Total VPN-IPv6 Rem. Rts : 0           Total VPN-IPv6 Rem. Act. Rts: 0        
Total VPN-IPv4 Bkup Rts : 0           Total VPN-IPv6 Bkup Rts     : 0        
 
Total VPN Supp. Rts     : 0           Total VPN Hist. Rts         : 0        
Total VPN Decay Rts     : 0          
 
Total L2-VPN Rem. Rts   : 0           Total L2VPN Rem. Act. Rts   : 0        
Total MVPN-IPv4 Rem Rts : 0           Total MVPN-IPv4 Rem Act Rts : 0        
Total MDT-SAFI Rem Rts  : 0           Total MDT-SAFI Rem Act Rts  : 0        
Total MSPW Rem Rts      : 0           Total MSPW Rem Act Rts      : 0        
Total RouteTgt Rem Rts  : 0           Total RouteTgt Rem Act Rts  : 0        
Total McVpnIPv4 Rem Rts : 0           Total McVpnIPv4 Rem Act Rts : 0        
Total MVPN-IPv6 Rem Rts : 0           Total MVPN-IPv6 Rem Act Rts : 0        
Total EVPN Rem Rts      : 0           Total EVPN Rem Act Rts      : 0        
Total FlowIpv4 Rem Rts  : 0           Total FlowIpv4 Rem Act Rts  : 0        
Total FlowIpv6 Rem Rts  : 0           Total FlowIpv6 Rem Act Rts  : 0        
 
===============================================================================
BGP Summary
===============================================================================
Legend : D - Dynamic Neighbor
===============================================================================
Neighbor
Description
                   AS PktRcvd InQ  Up/Down   State|Rcv/Act/Sent (Addr Family)
                      PktSent OutQ
-------------------------------------------------------------------------------
10.10.10.1                           
                200       166    0 01h20m14s 1/1/0 (IPv4)
                          163    0          
10.10.10.5
                200       149    0 00h57m41s 1/1/1 (VpnIPv4)
                          125    0          
-------------------------------------------------------------------------------
*A:PE6# show router 20 route-table
 
===============================================================================
Route Table (Service: 20)
===============================================================================
Dest Prefix[Flags]                            Type    Proto     Age        Pref
      Next Hop[Interface Name]                                    Metric  
-------------------------------------------------------------------------------
200.5.5.0/24                                  Remote  BGP VPN   01h04m10s  170
       10.10.10.5 (tunneled:BGP)                                    0
200.6.6.0/24                                  Local   Local     22h26m41s  0
       vprn-20-toCE                                                 0
-------------------------------------------------------------------------------
No. of Routes: 2
Flags: n = Number of times nexthop is repeated
       B = BGP backup route available
       L = LFA nexthop available
       S = Sticky ECMP requested
===============================================================================
*A:PE6#
 
*A:PE6# ping router 20 200.5.5.5 source 200.6.6.6
PING 200.5.5.5 56 data bytes
64 bytes from 200.5.5.5: icmp_seq=1 ttl=64 time=9.64ms.
64 bytes from 200.5.5.5: icmp_seq=2 ttl=64 time=9.35ms.
64 bytes from 200.5.5.5: icmp_seq=3 ttl=64 time=7.64ms.
64 bytes from 200.5.5.5: icmp_seq=4 ttl=64 time=9.02ms.
64 bytes from 200.5.5.5: icmp_seq=5 ttl=64 time=7.95ms.
 
---- 200.5.5.5 PING Statistics ----
5 packets transmitted, 5 packets received, 0.00% packet loss
round-trip min = 7.64ms, avg = 8.72ms, max = 9.64ms, stddev = 0.784ms
*A:PE6#

Data-Plane

  • PE-6 pushes 3 labels and forwards it to CSC-CE1.
    • Bottom Label : VPN label – 131070.
    • Middle Label: IPv4 label for next hop PE-5 (10.10.10.5/32). It is learned via labeled iBGP session. – 131069
    • Top Label: Transport label to reach CSC-CE1 (10.10.10.1/32). By default, router choses LDP-based transport tunnel – 131071
 Bottom Label:

*A:PE6# show router 20 fib 1 200.5.5.0/24
 
===============================================================================
FIB Display
===============================================================================
Prefix [Flags]                                              Protocol
  NextHop                                                  
-------------------------------------------------------------------------------
200.5.5.0/24                                                BGP_VPN
  10.10.10.5 (VPRN Label:131070 Transport:BGP)
-------------------------------------------------------------------------------
Total Entries : 1
-------------------------------------------------------------------------------
===============================================================================
*A:PE6#


Middle Label:
*A:PE6# show router bgp routes 10.10.10.5/32 hunt
===============================================================================
 BGP Router ID:10.10.10.6       AS:200         Local AS:200       
===============================================================================
 Legend -
 Status codes  : u - used, s - suppressed, h - history, d - decayed, * - valid
                 l - leaked, x - stale, > - best, b - backup, p - purge
 Origin codes  : i - IGP, e - EGP, ? - incomplete
 
===============================================================================
BGP IPv4 Routes
===============================================================================
-------------------------------------------------------------------------------
RIB In Entries
-------------------------------------------------------------------------------
Network        : 10.10.10.5/32
Nexthop        : 10.10.10.1
Path Id        : None                  
From           : 10.10.10.1 >>>>>>>>>>>>>>>>>
Res. Nexthop   : 10.1.6.1 (LDP) >>>>>>>>>>>>>>>>>
Local Pref.    : 100                    Interface Name : NotAvailable
Aggregator AS  : None                   Aggregator     : None
Atomic Aggr.   : Not Atomic             MED            : None
AIGP Metric    : None                  
Connector      : None
Community      : target:100:30
Cluster        : No Cluster Members
Originator Id  : None                   Peer Router Id : 10.10.10.1
Fwd Class      : None                   Priority       : None
IPv4 Label     : 131069          >>>>>>>>>>>>>>>>>>>>>>>>>      
Flags          : Used  Valid  Best  IGP  AS-Loop 
Route Source   : Internal
AS-Path        : 100 200
Route Tag      : 0                     
Neighbor-AS    : 100
Orig Validation: NotFound              
Source Class   : 0                      Dest Class     : 0
Add Paths Send : Default               
Last Modified  : 03h17m24s             
 
-------------------------------------------------------------------------------
RIB Out Entries
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
Routes : 1
===================================

Top Label:

*A:PE6# show router ldp bindings active prefixes prefix 10.10.10.1/32
 
===============================================================================
LDP Bindings (IPv4 LSR ID 10.10.10.6)
             (IPv6 LSR ID ::)
===============================================================================
Legend: U - Label In Use,  N - Label Not In Use, W - Label Withdrawn
        WP - Label Withdraw Pending, BU - Alternate For Fast Re-Route
        (S) - Static       (M) - Multi-homed Secondary Support
        (B) - BGP Next Hop (BU) - Alternate Next-hop for Fast Re-Route
        (C) - FEC resolved with class-based-forwarding
===============================================================================
LDP IPv4 Prefix Bindings (Active)
===============================================================================
Prefix                                      Op              IngLbl    EgrLbl
EgrNextHop                                  EgrIf/LspId              
-------------------------------------------------------------------------------
10.10.10.1/32                               Push              --      131071
10.1.6.1                                    1/1/2                     
                                                                      
-------------------------------------------------------------------------------
No. of IPv4 Prefix Active Bindings: 1
===============================================================================
  • CSC-CE1 pops LDP label and swaps the BGP label with the new label received from CSC-PE3 for PE-5’s address – 131068. It forwards it to CSC-PE3.
*A:CSC-CE1# show router bgp routes 10.10.10.5/32 hunt 
===============================================================================
 BGP Router ID:10.10.10.1       AS:200         Local AS:200       
===============================================================================
 Legend -
 Status codes  : u - used, s - suppressed, h - history, d - decayed, * - valid
                 l - leaked, x - stale, > - best, b - backup, p - purge
 Origin codes  : i - IGP, e - EGP, ? - incomplete
 
===============================================================================
BGP IPv4 Routes
===============================================================================
-------------------------------------------------------------------------------
RIB In Entries
-------------------------------------------------------------------------------
Network        : 10.10.10.5/32
Nexthop        : 10.1.3.3
Path Id        : None                  
From           : 10.1.3.3
Res. Nexthop   : 10.1.3.3
Local Pref.    : None                   Interface Name : toR3
Aggregator AS  : None                   Aggregator     : None
Atomic Aggr.   : Not Atomic             MED            : None
AIGP Metric    : None                  
Connector      : None
Community      : target:100:30
Cluster        : No Cluster Members
Originator Id  : None                   Peer Router Id : 10.10.10.3
Fwd Class      : None                   Priority       : None
IPv4 Label     : 131068        >>>>>>>>>>>>>>>>>>>>>>        
Flags          : Used  Valid  Best  IGP  AS-Loop 
Route Source   : External
AS-Path        : 100 200
Route Tag      : 0                     
Neighbor-AS    : 100
Orig Validation: NotFound              
Source Class   : 0                      Dest Class     : 0
Add Paths Send : Default               
Last Modified  : 03h24m43s             
 
*A:CSC-CE1# show router bgp inter-as-label
 
===============================================================================
BGP Inter-AS labels
Flags: B - entry has backup, P - entry is promoted
===============================================================================
NextHop                       Received       Advertised     Label
                              Label          Label          Origin
-------------------------------------------------------------------------------
10.1.3.3                      131068         131069         External
10.10.10.6                    131071         131067         InternalLdp
-------------------------------------------------------------------------------
Total Labels allocated:   2
===============================================================================
*A:CSC-CE1#
  • CSC-PE3 performs two actions and forwards to CSC-PE4:
    • Swaps the top BGP label with CSC VPRN label. The VPRN label can be checked either by VPN route for PE-5 or label exchange table  – 131065
    • Pushes the transport label for next hop CSC-PE4 – 131071
Swap:

*A:CSC-PE3# show router 30 bgp inter-as-label
 
===============================================================================
BGP Inter-AS labels
Flags: B - entry has backup, P - entry is promoted
===============================================================================
NextHop                       Received       Advertised     Label
                              Label          Label          Origin
-------------------------------------------------------------------------------
10.10.10.4                    131065         131068         Internal
-------------------------------------------------------------------------------
Total Labels allocated:   1
===============================================================================
 
 
*A:CSC-PE3# show router 30 fib 1 10.10.10.5/32
 
===============================================================================
FIB Display
===============================================================================
Prefix [Flags]                                              Protocol
  NextHop                                                  
-------------------------------------------------------------------------------
10.10.10.5/32                                               BGP_VPN
  10.10.10.4 (VPRN Label:131065 Transport:LDP)
-------------------------------------------------------------------------------
Total Entries : 1
-------------------------------------------------------------------------------
===============================================================================
*A:CSC-PE3#


Push:

*A:CSC-PE3# show router ldp bindings active prefixes prefix 10.10.10.4/32
 
===============================================================================
LDP Bindings (IPv4 LSR ID 10.10.10.3)
             (IPv6 LSR ID ::)
===============================================================================
Legend: U - Label In Use,  N - Label Not In Use, W - Label Withdrawn
        WP - Label Withdraw Pending, BU - Alternate For Fast Re-Route
        (S) - Static       (M) - Multi-homed Secondary Support
        (B) - BGP Next Hop (BU) - Alternate Next-hop for Fast Re-Route
        (C) - FEC resolved with class-based-forwarding
===============================================================================
LDP IPv4 Prefix Bindings (Active)
===============================================================================
Prefix                                      Op              IngLbl    EgrLbl
EgrNextHop                                  EgrIf/LspId              
-------------------------------------------------------------------------------
10.10.10.4/32                               Push              --      131071
10.3.4.4                                    1/1/1                     
                                                                      
-------------------------------------------------------------------------------
No. of IPv4 Prefix Active Bindings: 1
===============================================================================
*A:CSC-PE3#      
  • CSC-PE4 pops the LDP label and swaps the CSC VPRN label with ExtCarCarVPRN label received from CSC-CE2 for PE5 address – 131067, forwards it to CSC-CE2. It can be verified by checking VPN route for PE5 or label exchange table.
 *A:CSC-PE4# show router bgp inter-as-label 
 
===============================================================================
BGP Inter-AS labels
Flags: B - entry has backup, P - entry is promoted
===============================================================================
NextHop                       Received       Advertised     Label
                              Label          Label          Origin
-------------------------------------------------------------------------------
10.2.4.2                      131067         131065         ExtCarCarVpn
-------------------------------------------------------------------------------
Total Labels allocated:   1
===============================================================================
*A:CSC-PE4#
 
*A:CSC-PE4# show router 30 bgp routes 10.10.10.5/32 hunt         
===============================================================================
 BGP Router ID:10.10.10.4       AS:100         Local AS:100       
===============================================================================
 Legend -
 Status codes  : u - used, s - suppressed, h - history, d - decayed, * - valid
                 l - leaked, x - stale, > - best, b - backup, p - purge
 Origin codes  : i - IGP, e - EGP, ? - incomplete
 
===============================================================================
BGP IPv4 Routes
===============================================================================
-------------------------------------------------------------------------------
RIB In Entries
-------------------------------------------------------------------------------
Network        : 10.10.10.5/32
Nexthop        : 10.2.4.2
Path Id        : None                  
From           : 10.2.4.2
Res. Nexthop   : 10.2.4.2
Local Pref.    : None                   Interface Name : toCSCCE2
Aggregator AS  : None                   Aggregator     : None
Atomic Aggr.   : Not Atomic             MED            : 100
AIGP Metric    : None                  
Connector      : None
Community      : No Community Members
Cluster        : No Cluster Members
Originator Id  : None                   Peer Router Id : 10.10.10.2
Fwd Class      : None                   Priority       : None
IPv4 Label     : 131067           >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>     
Flags          : Used  Valid  Best  IGP 
Route Source   : External
AS-Path        : 200
Route Tag      : 0                     
Neighbor-AS    : 200
Orig Validation: NotFound              
Source Class   : 0                      Dest Class     : 0
Add Paths Send : Default               
Last Modified  : 03h47m01s             
 
-------------------------------------------------------------------------------
RIB Out Entries
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
Routes : 1
===============================================================================
  • CSC-CE2 swaps the top ExtCarCar VPRN with the new label received from PE5 – 131071. This is the LDP transport label for PE5.
*A:CSC-CE2# show router bgp inter-as-label 
 
===============================================================================
BGP Inter-AS labels
Flags: B - entry has backup, P - entry is promoted
===============================================================================
NextHop                       Received       Advertised     Label
                              Label          Label          Origin
-------------------------------------------------------------------------------
10.2.4.4                      131066         131066         External
10.10.10.5                    131071         131067         InternalLdp
-------------------------------------------------------------------------------
Total Labels allocated:   2
===============================================================================
 
*A:CSC-CE2# show router ldp bindings active prefixes prefix 10.10.10.5/32
 
===============================================================================
LDP Bindings (IPv4 LSR ID 10.10.10.2)
             (IPv6 LSR ID ::)
===============================================================================
Legend: U - Label In Use,  N - Label Not In Use, W - Label Withdrawn
        WP - Label Withdraw Pending, BU - Alternate For Fast Re-Route
        (S) - Static       (M) - Multi-homed Secondary Support
        (B) - BGP Next Hop (BU) - Alternate Next-hop for Fast Re-Route
        (C) - FEC resolved with class-based-forwarding
===============================================================================
LDP IPv4 Prefix Bindings (Active)
===============================================================================
Prefix                                      Op              IngLbl    EgrLbl
EgrNextHop                                  EgrIf/LspId              
-------------------------------------------------------------------------------
10.10.10.5/32                               Push              --      131071
10.2.5.5                                    1/1/2                     
                                                                      
-------------------------------------------------------------------------------
No. of IPv4 Prefix Active Bindings: 1
===============================================================================
*A:CSC-CE2# 
  • PE5 pops the LDP label and looks up the VPN label that it corresponds to VPRN 20. It then checks its routing table and forwards the unlabeled IP packet to local interface.
 *A:PE5# show router mpls-labels label 32 131071  in-use 
 
=================================================================
MPLS Labels from 32 to 131071 (In-use)
=================================================================
Label               Label Type          Label Owner
-----------------------------------------------------------------
131069              dynamic             ILDP
131070              dynamic             VPRN
131071              dynamic             ILDP
-----------------------------------------------------------------
In-use labels (Owner: All) in specified range   : 3
In-use labels in entire range                   : 3
=================================================================
*A:PE5#
*A:PE5# show router 20 fib 1
 
===============================================================================
FIB Display
===============================================================================
Prefix [Flags]                                              Protocol
  NextHop                                                  
-------------------------------------------------------------------------------
200.5.5.0/24                                                LOCAL
  200.5.5.0 (vprn-20-toCE)
200.6.6.0/24                                                BGP_VPN
  10.10.10.6 (VPRN Label:131070 Transport:BGP)
-------------------------------------------------------------------------------
Total Entries : 2
-------------------------------------------------------------------------------
===============================================================================
*A:PE5#

CSC- ISP Customer Carrier

If the customer carrier is ISP providing internet connectivity:

  • No VRF config is required in Customer carrier’s network, so end-customer traffic will be only on single csc vrf.
  • Customer carrier can be either purely IP or MPLS.
  • Customer carrier PE routers (PE-3 and PE-4) in different sites must run iBGP to exchange customer routes.

Internet routes are exchanged directly between customer carrier PE routers using iBGP. LDP shortcuts are used for next-hop resolution.

  • Remove the iBGP config between PE and CSC-CE configured in previous section.
  • Modify the eBGP configured between CSC-CE to CSC-PE to advertise the LDP prefixes.
*A:CSC-CE1>config>router>policy-options# info 
policy-statement "AdvSystemIP"
                entry 10
                    from
                        protocol ldp
                        prefix-list "SystemIP"
                    exit             
                    to
                        protocol bgp
                    exit
                    action accept
                    exit
                exit
                default-action reject
            exit
*A:CSC-CE1>config>router>bgp# info
----------------------------------------------
            group "toCSC"
                family ipv4
                loop-detect off
                export "AdvSystemIP"
                peer-as 100
                neighbor 10.1.3.3
                    advertise-label ipv4 include-ldp-prefix
                exit
            exit
            no shutdown
----------------------------------------------

*A:CSC-CE2>config>router>policy-options# info  
policy-statement "AdvSystemIP"
                entry 10
                    from
                        protocol ldp
                        prefix-list "SystemIP"
                    exit
                    to
                        protocol bgp
                    exit
                    action accept
                    exit
                exit
                default-action reject
            exit
*A:CSC-CE2>config>router>bgp# info
----------------------------------------------
            group "toCSC"
                family ipv4
                loop-detect off
                export "AdvSystemIP"
                peer-as 100
                neighbor 10.2.4.4
                    advertise-label ipv4 include-ldp-prefix
                exit
            exit
            no shutdown
----------------------------------------------
 
  • Redistribute the received address from different site in IGP/OSPF.
*A:CSC-CE1>config>router>ospf# info 
----------------------------------------------
            asbr
            export "AdvSite2"
            area 0.0.0.0
                interface "system"
                    no shutdown
                exit
                interface "toR6"
                    interface-type point-to-point
                    no shutdown
                exit
            exit
            no shutdown
*A:CSC-CE2>config>router>ospf# info 
----------------------------------------------
            asbr
            export "AdvSite1"
            area 0.0.0.0
                interface "system"
                    no shutdown
                exit
                interface "toR5"
                    interface-type point-to-point
                    no shutdown
                exit
            exit
            no shutdown
  • CSC-CE advertises the received prefixes to LDP, which allows the establishment of LDP tunnel between PE routers. These LDP tunnels will be used for next hop resolution
*A:CSC-CE1>config>router>policy-options# info 
----------------------------------------------
policy-statement "toLDP"
                entry 10
                    from
                        protocol bgp
                        prefix-list "Site2prefix"
                    exit
                    action accept
                    exit
                exit
            exit
*A:CSC-CE1>config>router>ldp# info
----------------------------------------------
            export-tunnel-table "toLDP"
            interface-parameters
                interface "toR6"
exit
*A:CSC-CE2>config>router>policy-options# info 
----------------------------------------------
policy-statement "toLDP"
                entry 10
                    from
                        protocol bgp
                        prefix-list "Site1Prefix"
                    exit
                    action accept
                    exit
                exit
            exit
*A:CSC-CE2>config>router>ldp# info
----------------------------------------------
            export-tunnel-table "toLDP"
            interface-parameters
                interface "toR5"
exit
  • Configure family ipv4 under MPBGP between PE routers to allow exchange of Internet routes and also apply an export policy. Also configure next-hop-resolution as ldp tunnel.
*A:PE6>config>router>bgp# info 
----------------------------------------------
            next-hop-resolution
                shortcut-tunnel
                    family ipv4
                        resolution-filter
                            ldp
                        exit
                        resolution filter
                    exit
                exit
            exit
            group "MPBGP"
                family ipv4 vpn-ipv4
                export "IesLoop"
                peer-as 200
                neighbor 10.10.10.5
                exit
            exit
            no shutdown
----------------------------------------------
*A:PE6>config>router>policy-options# info
----------------------------------------------
            prefix-list "IES-Loopback"
                prefix 100.6.6.0/24 longer
            exit
            policy-statement "IesLoop"
                entry 10
                    from
                        protocol direct
                        prefix-list "IES-Loopback"
                    exit
                    action accept
                    exit
                exit
            exit
----------------------------------------------
*A:PE5>config>router>bgp# info 
----------------------------------------------
            next-hop-resolution
                shortcut-tunnel
                    family ipv4
                        resolution-filter
                            ldp
                        exit
                        resolution filter
                    exit
                exit
            exit
            group "MPBGP"
                family ipv4 vpn-ipv4
                export "IesLoop"
                peer-as 200
                neighbor 10.10.10.6
                exit
            exit
            no shutdown
----------------------------------------------
*A:PE5>config>router>policy-options# info
----------------------------------------------
            prefix-list "IES-Loopback"
                prefix 100.5.5.0/24 longer
            exit
            policy-statement "IesLoop"
                entry 10
                    from
                        protocol direct
                        prefix-list "IES-Loopback"
                    exit
                    action accept
                    exit
                exit
            exit
----------------------------------------------
  • Verify the reachability for Internet and VPRN customer.
 *A:PE6# show router route-table 
 
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags]                            Type    Proto     Age        Pref
      Next Hop[Interface Name]                                    Metric  
-------------------------------------------------------------------------------
10.1.6.0/27                                   Local   Local     01d02h35m  0
       toR1                                                         0
10.10.10.1/32                                 Remote  OSPF      01d02h35m  10
       10.1.6.1                                                     100
10.10.10.5/32                                 Remote  OSPF      00h15m02s  150
       10.1.6.1                                                     1
10.10.10.6/32                                 Local   Local     01d02h35m  0
       system                                                       0
100.5.5.0/24                                  Remote  BGP       00h00m00s  170
       10.10.10.5 (tunneled)                                        0
100.6.6.0/24                                  Local   Local     01d02h35m  0
       ies-10-toCE                                                  0
-------------------------------------------------------------------------------
No. of Routes: 6
Flags: n = Number of times nexthop is repeated
       B = BGP backup route available
       L = LFA nexthop available
       S = Sticky ECMP requested
===============================================================================
*A:PE6# ping 100.5.5.5 source 100.6.6.6
PING 100.5.5.5 56 data bytes
64 bytes from 100.5.5.5: icmp_seq=1 ttl=64 time=8.92ms.
64 bytes from 100.5.5.5: icmp_seq=2 ttl=64 time=7.77ms.
64 bytes from 100.5.5.5: icmp_seq=3 ttl=64 time=9.28ms.
64 bytes from 100.5.5.5: icmp_seq=4 ttl=64 time=8.01ms.
64 bytes from 100.5.5.5: icmp_seq=5 ttl=64 time=6.62ms.
 
---- 100.5.5.5 PING Statistics ----
5 packets transmitted, 5 packets received, 0.00% packet loss
round-trip min = 6.62ms, avg = 8.12ms, max = 9.28ms, stddev = 0.935ms
*A:PE6# ping router 20 200.5.5.5 source 200.6.6.6
PING 200.5.5.5 56 data bytes
64 bytes from 200.5.5.5: icmp_seq=1 ttl=64 time=8.34ms.
64 bytes from 200.5.5.5: icmp_seq=2 ttl=64 time=9.87ms.
64 bytes from 200.5.5.5: icmp_seq=3 ttl=64 time=7.84ms.
64 bytes from 200.5.5.5: icmp_seq=4 ttl=64 time=8.55ms.
64 bytes from 200.5.5.5: icmp_seq=5 ttl=64 time=8.89ms.
 
---- 200.5.5.5 PING Statistics ----
5 packets transmitted, 5 packets received, 0.00% packet loss
round-trip min = 7.84ms, avg = 8.70ms, max = 9.87ms, stddev = 0.677ms

Data-Plane

  • PE-6 determines the routing table for destination 100.5.5.0/24 and next hop is PE-5 10.10.10.5 learned via BGP tunnel. It pushes the LDP label – 131069
*A:PE6# show router route-table 100.5.5.0/24 
 
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags]                            Type    Proto     Age        Pref
      Next Hop[Interface Name]                                    Metric  
-------------------------------------------------------------------------------
100.5.5.0/24                                  Remote  BGP       02h26m11s  170
       10.10.10.5 (tunneled)                                        0
-------------------------------------------------------------------------------
No. of Routes: 1
Flags: n = Number of times nexthop is repeated
       B = BGP backup route available
       L = LFA nexthop available
       S = Sticky ECMP requested
===============================================================================
*A:PE6#
  • From tunnel table, we can see that LDP is used for transport.
*A:PE6# show router tunnel-table 
 
===============================================================================
IPv4 Tunnel Table (Router: Base)
===============================================================================
Destination       Owner     Encap TunnelId  Pref     Nexthop        Metric
-------------------------------------------------------------------------------
10.10.10.1/32     ldp       MPLS  65537     9        10.1.6.1       100
10.10.10.5/32     ldp       MPLS  65538     9        10.1.6.1       1
-------------------------------------------------------------------------------
Flags: B = BGP backup route available
       E = inactive best-external BGP route
===============================================================================
*A:PE6#
 
*A:PE6# show router ldp bindings active prefixes prefix 10.10.10.5/32
 
===============================================================================
LDP Bindings (IPv4 LSR ID 10.10.10.6)
             (IPv6 LSR ID ::)
===============================================================================
Legend: U - Label In Use,  N - Label Not In Use, W - Label Withdrawn
        WP - Label Withdraw Pending, BU - Alternate For Fast Re-Route
        (S) - Static       (M) - Multi-homed Secondary Support
        (B) - BGP Next Hop (BU) - Alternate Next-hop for Fast Re-Route
        (C) - FEC resolved with class-based-forwarding
===============================================================================
LDP IPv4 Prefix Bindings (Active)
===============================================================================
Prefix                                      Op              IngLbl    EgrLbl
EgrNextHop                                  EgrIf/LspId              
-------------------------------------------------------------------------------
10.10.10.5/32                               Push              --      131069
10.1.6.1                                    1/1/2                     
                                                                      
10.10.10.5/32                               Swap            131068    131069
10.1.6.1                                    1/1/2                     
                                                                      
-------------------------------------------------------------------------------
No. of IPv4 Prefix Active Bindings: 2
===============================================================================
*A:PE6#
  • CSC-CE1 consults its LDP forwarding table and swaps the label 131069 with 131068.
*A:CSC-CE1# show router ldp bindings active 
 
===============================================================================
LDP Bindings (IPv4 LSR ID 10.10.10.1)
             (IPv6 LSR ID ::)
===============================================================================
Legend: U - Label In Use,  N - Label Not In Use, W - Label Withdrawn
        WP - Label Withdraw Pending, BU - Alternate For Fast Re-Route
        (S) - Static       (M) - Multi-homed Secondary Support
        (B) - BGP Next Hop (BU) - Alternate Next-hop for Fast Re-Route
        (C) - FEC resolved with class-based-forwarding
===============================================================================
LDP IPv4 Prefix Bindings (Active)
===============================================================================
Prefix                                      Op              IngLbl    EgrLbl
EgrNextHop                                  EgrIf/LspId              
-------------------------------------------------------------------------------
10.10.10.1/32                               Pop             131071      --
  --                                          --                      
                                                                      
10.10.10.5/32(B)                            Swap            131069    131068
10.1.3.3                                    1/1/3                     
                                                                      
10.10.10.6/32                               Push              --      131071
10.1.6.6                                    1/1/2                     
                                                                      
-------------------------------------------------------------------------------
No. of IPv4 Prefix Active Bindings: 3
  • CSC-PE3 performs the following action and forwards to CSC-PE4 with 2 labels:
    • Bottom Label: CSC VPRN label. It consults its label exchange table and swaps the label 131068 with CSC VPRN label received from CSC-PE4 – 131065.
    • Top Label: Transport label to reach CSC-PE4 – 131071
Bottom:
*A:CSC-PE3# show router 30 bgp inter-as-label
 
===============================================================================
BGP Inter-AS labels
Flags: B - entry has backup, P - entry is promoted
===============================================================================
NextHop                       Received       Advertised     Label
                              Label          Label          Origin
-------------------------------------------------------------------------------
10.10.10.4                    131065         131068         Internal
-------------------------------------------------------------------------------
Total Labels allocated:   1
===============================================================================
*A:CSC-PE3#



Top:
*A:CSC-PE3# show router ldp bindings active prefixes prefix 10.10.10.4/32
 
===============================================================================
LDP Bindings (IPv4 LSR ID 10.10.10.3)
             (IPv6 LSR ID ::)
===============================================================================
Legend: U - Label In Use,  N - Label Not In Use, W - Label Withdrawn
        WP - Label Withdraw Pending, BU - Alternate For Fast Re-Route
        (S) - Static       (M) - Multi-homed Secondary Support
        (B) - BGP Next Hop (BU) - Alternate Next-hop for Fast Re-Route
        (C) - FEC resolved with class-based-forwarding
===============================================================================
LDP IPv4 Prefix Bindings (Active)
===============================================================================
Prefix                                      Op              IngLbl    EgrLbl
EgrNextHop                                  EgrIf/LspId              
-------------------------------------------------------------------------------
10.10.10.4/32                               Push              --      131071
10.3.4.4                                    1/1/1                     
                                                                      
-------------------------------------------------------------------------------
No. of IPv4 Prefix Active Bindings: 1
===============================================================================
*A:CSC-PE3# 
  • CSC-PE4 pops the LDP label and swaps the CSC VPRN label (131065) with ExtCarCar VPRN label (131067) received from CSC-CE2.
*A:CSC-PE4# show router bgp inter-as-label 
 
===============================================================================
BGP Inter-AS labels
Flags: B - entry has backup, P - entry is promoted
===============================================================================
NextHop                       Received       Advertised     Label
                              Label          Label          Origin
-------------------------------------------------------------------------------
10.2.4.2                      131067         131065         ExtCarCarVpn
-------------------------------------------------------------------------------
Total Labels allocated:   1
===============================================================================
*A:CSC-PE4#
  • CSC-CE2 swaps the ExtCarCarVPN label (131067) advertised to CSC-PE4 with the LDP label 131071 received from PE5
*A:CSC-CE2# show router bgp inter-as-label 
 
===============================================================================
BGP Inter-AS labels
Flags: B - entry has backup, P - entry is promoted
===============================================================================
NextHop                       Received       Advertised     Label
                              Label          Label          Origin
-------------------------------------------------------------------------------
10.10.10.5                    131071         131067         InternalLdp
-------------------------------------------------------------------------------
Total Labels allocated:   1
===============================================================================
  • PE5 pops the LDP label and consults its global routing table to forward to local interface.
*A:PE5# show router route-table 100.5.5.0/24 
 
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags]                            Type    Proto     Age        Pref
      Next Hop[Interface Name]                                    Metric  
-------------------------------------------------------------------------------
100.5.5.0/24                                  Local   Local     01d05h21m  0
       ies-10-toCE                                                  0
-------------------------------------------------------------------------------
No. of Routes: 1
Flags: n = Number of times nexthop is repeated
       B = BGP backup route available
       L = LFA nexthop available
       S = Sticky ECMP requested
===============================================================================
*A:PE5#

Inter-AS VPRN Series:

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Categories: IPv4, L3VPN, MPLS, Nokia

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