LDP VPLS Using BGP Auto-Discovery

This chapter provides information about LDP VPLS using BGP Auto-Discovery.

Topics in this chapter include:

Applicability

This chapter was initially written for SR OS Release 9.0.R3. The CLI in this edition is based on SR OS Release 20.10.R2. There are no prerequisites for this configuration.

Knowledge of BGP-auto-discovery RFC 6074 architecture and functionality, RFC 4447 Pseudo-wire set-up using label distribution protocol is assumed throughout this chapter, as well as knowledge of Multi-Protocol BGP (MP-BGP).

Overview

MPLS-based Virtual Private LAN Services (VPLS) may have many different provisioning models to allow the signaling of pseudowires between Provider Edge (PE) routers containing VPLS instances.

Network Management System (NMS) provisioning using Label Distribution Protocol (LDP) signaling is a well understood method of provisioning of Layer 2 VPLS services as described in RFC 4762. This relies on the provisioning of pseudowires between VPLS instances using LDP signaling with a common Virtual Circuit (VC) identifier within the label mapping message to instantiate pseudowires.

Border Gateway Protocol (BGP) Auto-Discovery (RFC 6074) is an alternative method of provisioning of Layer 2 PE routers containing VPLS service instances to those described above where PEs in a common VPLS instance are automatically discovered using BGP Auto-Discovery (BGP-AD) techniques.

Each PE router advertises the presence of VPLS instances to other PE routers using defined parameters within a BGP update message.

LDP is used as the pseudowire signaling protocol and relies on the auto-discovery of VPLS endpoints to instantiate pseudowires instead of manually provisioning virtual circuits. Locally configured parameters, along with BGP learned parameters, are used to determine local and remote VPLS endpoints, which are used by LDP to signal service labels to peer routers.

Example topology shows the example topology with six SR OS nodes located in the same autonomous system (AS).There are three PEs and RR-6 will act as a route reflector for the AS. The PE routers are all VPLS-aware. The provider (P) routers are VPLS-unaware and do not take part in the BGP process. A full mesh VPLS between PE-1, PE-2, and PE-3 is described.

Figure 1. Example topology

The following configuration tasks are completed as a prerequisite:

  • IS-IS or OSPF is enabled on all network interfaces between each of the PE/P routers and route reflector RR-6.

  • MPLS is configured on all interfaces between PE and P routers; MPLS is not required between P-4 and RR-6.

  • LDP is configured on interfaces between PE and P routers; LDP is not required between P-4 and RR-6.

  • The RSVP protocol must be enabled.

BGP-AD

In this architecture, a VPLS service is a collection of local VPLS instances present on a number of PEs in a provider network. In this context, VPLS-aware devices are PE routers. Each VPLS instance has a unique identifier known as the VPLS identifier (VPLS-ID). All PEs that have this VPLS instance present will have a common VPLS-ID configured.

Each VPLS instance within a PE contains a Virtual Switching Instance (VSI). The VPLS attachment circuits and pseudowires are associated with the VSI. Each VSI within a VPLS has a unique identifier called the VSI identifier (VSI-ID) and is a concatenation of the VPLS-ID plus an IP address, usually the system IP address.

The PEs communicate with each other at the control plane level by means of BGP updates containing BGP Layer 2 Network Layer Reachability Information (NLRI). Each update contains enough information for a PE to determine the presence of other local VPLS instances on peering PEs. In turn, this allows peer PE routers to set up pseudowire connectivity using LDP signaling for data flow between peers containing a local VPLS within the same VPLS instances.

Each update contains parameters usually associated with Multi-Protocol BGP updates:

  • NLRI encoded as route target (RT)—usually the VPLS-ID—and PE system address.

  • Next-Hop — The system IP address of the sending PE router.

  • Extended communities — Contains the RT extended community and the VPLS-ID as community values.

Each VPLS instance is configured with import and export RT extended communities to create the required pseudowire topology by controlling the distribution of each NLRI.

This chapter describes the provisioning of a VPLS instance across three PE routers. A full mesh of pseudowires interconnects the VSI of each PE within the VPLS instance. A single attachment circuit is also configured on each VSI.

Configuration

The first step is to configure an MP-iBGP session using the L2-VPN address family between each of the PEs and the RR.

The configuration for the PEs is as follows:

# on PE-1, PE-2, and PE-3:
configure
     router Base
        autonomous-system 65536
        bgp
            group "internal"
                family l2-vpn
                peer-as 65536
                neighbor 192.0.2.6
                exit
            exit
            no shutdown
        exit
    exit

The IP addresses can be derived from Example topology.

The configuration for RR-6 is as follows:

# on RR-6:
configure
     router Base
     autonomous-system 65536 
        bgp
            group "rr-internal"
                family l2-vpn
                cluster 1.1.1.1
                peer-as 65536
                neighbor 192.0.2.1
                exit
                neighbor 192.0.2.2
                exit
                neighbor 192.0.2.3
                exit
            exit
            no shutdown
        exit
    exit

On PE-1, the BGP session with RR-6 is established with address family L2-VPN capability negotiated, as follows:

*A:PE-1# show router bgp neighbor 192.0.2.6
 
===============================================================================
BGP Neighbor
===============================================================================
-------------------------------------------------------------------------------
Peer                 : 192.0.2.6
Description          : (Not Specified)
Group                : internal
-------------------------------------------------------------------------------
Peer AS              : 65536            Peer Port            : 50757
Peer Address         : 192.0.2.6
Local AS             : 65536            Local Port           : 179
Local Address        : 192.0.2.1
Peer Type            : Internal         Dynamic Peer         : No
State                : Established      Last State           : Established
Last Event           : recvOpen
Last Error           : Cease (Connection Collision Resolution)
Local Family         : L2-VPN
Remote Family        : L2-VPN
---snip---

On RR-6, the following BGP sessions are established with each PE for the L2-VPN address family:

*A:RR-6# show router bgp summary all

===============================================================================
BGP Summary
===============================================================================
Legend : D - Dynamic Neighbor
===============================================================================
Neighbor
Description
ServiceId          AS PktRcvd InQ  Up/Down   State|Rcv/Act/Sent (Addr Family)
                      PktSent OutQ
-------------------------------------------------------------------------------
192.0.2.1
Def. Instance  65536        6    0 00h01m35s 0/0/0 (L2VPN)
                            6    0
192.0.2.2
Def. Instance  65536        6    0 00h01m35s 0/0/0 (L2VPN)
                            6    0
192.0.2.3
Def. Instance  65536        6    0 00h01m35s 0/0/0 (L2VPN)
                            6    0

-------------------------------------------------------------------------------

A full mesh of RSVP Label Switched Paths (LSPs) is configured between the PE routers. For reference, the MPLS interface configuration and LSPs for PE-1 to PE-2 and PE-3 is as follows:

# on PE-1:
configure 
    router Base
        mpls 
            interface "int-PE-1-PE-2"
                no shutdown
            exit
            interface "int-PE-1-P-4"
                no shutdown
            exit            
            path "loose"
                no shutdown
            exit
            lsp "LSP-PE-1-PE-2"
                to 192.0.2.2
                primary "loose"
                exit
                no shutdown
            exit
            lsp "LSP-PE-1-PE-3"
                to 192.0.2.3
                primary "loose"
                exit
                no shutdown
            exit
            no shutdown

VPLS PE configuration

Pseudowire templates

Pseudowire templates are used by BGP to dynamically instantiate Service Distribution Point (SDP) bindings. For a given service, pseudowire templates signal the egress service de-multiplexer labels used by remote PEs to reach the local PE.

The template determines the signaling parameters of the pseudowire, control word presence, plus other usage characteristics such as Split Horizon Groups (SHGs), MAC-pinning, filters, and so on.

The MPLS transport tunnel between PE routers can be signaled using either LDP or RSVP.

LDP-based pseudowires can be automatically instantiated; RSVP-based SDPs have to be pre-provisioned.

Pseudowire templates for auto-SDP creation using LDP

In order to use an LDP transport tunnel for data flow between PEs, it is necessary for link layer LDP to be configured between all PEs/Ps so that a transport label for each PE system interface address is available. Using this mechanism, SDPs can be auto-instantiated with SDP-IDs starting at 32767. Any subsequent SDPs created use SDP-IDs decrementing from this value.

A pseudowire template is required which may contain an SHG. Each SDP created with this template is contained within the configured SHG so that traffic cannot be forwarded between them.

# on PE-1, PE-2, PE-3:
configure
    service 
        pw-template 1 name "PW1" create
            split-horizon-group "vpls-shg"
            exit
        exit

A pseudowire template can also be created that does not contain a split horizon group. The split horizon group can then be specified when the pw-template is included within the service.

# on PE-1, PE-2, PE-3:
configure
    service 
        pw-template 2 name "PW2" create
        exit

Pseudowire templates for provisioned SDPs using RSVP

To use an RSVP tunnel as transport between PEs, it is necessary to bind the RSVP LSPs to the SDPs between each PE.

On PE-1, SDP 12 from PE-1 to PE-2 is configured as follows:

# on PE-1:
configure 
    service 
        sdp 12 mpls create
            description "RSVP-based SDP from PE-1 to PE-2"
            far-end 192.0.2.2
            lsp "LSP-PE-1-PE-2"
            no shutdown
        exit

To create an SDP within a service that uses the RSVP transport tunnel, a pseudowire template is required that has the use-provisioned-sdp parameter.

# on PE-1, PE-2, PE-3:
configure 
    service 
        pw-template 3 name "PW3" use-provisioned-sdp create            
            exit 
        exit 

Alternatively, the prefer-provisioned-sdp parameter can be used, see chapter LDP VPLS Using BGP Auto-Discovery — Prefer Provisioned SDP.

VPLS BGP-AD using auto-provisioned SDPs

Figure 2. VPLS instance with auto-provisioned SDPs

VPLS instance with auto-provisioned SDPs shows a schematic of a VPLS instance where the SDPs are auto-provisioned. SDPs are instantiated by a PE router using LDP signaling upon receipt of BGP Auto-Discovery (BGP-AD) updates from peer PE routers.

PE-1 configuration:

The following output shows the configuration required for a VPLS service using a pseudowire template configured for auto-provisioning of SDPs.

# on PE-1:
configure
    service
        vpls 3 name "VPLS3" customer 1 create
            bgp
                route-distinguisher 65536:3
                route-target export target:65536:3 import target:65536:3
                pw-template-binding 2 split-horizon-group "vpls-shg" 
                    import-rt "target:65536:3"
                exit
            exit
            bgp-ad
                vpls-id 65536:3
                vsi-id
                    prefix 192.0.2.1
                exit
                no shutdown
            exit
            sap 1/1/4:3.0 create
            exit
            no shutdown
        exit

Within the bgp context, the pseudowire template is referenced which can be linked to an SHG and an import RT, if required.

Within the bgp-ad context, the signaling parameters are configured. These are two parameters used by each PE to determine the presence of a VPLS instance on a PE router. In turn, these are translated into endpoint identifiers for LDP signaling of pseudowires. As previously discussed, these parameters are:

  • VPLS-ID — a unique identifier of the VPLS instance. Each PE that is a member of a VPLS must share the same VPLS-ID. This is inserted as an extended community value in the format AS:n. In this case, the VPLS-ID for VPLS 3 is 65536:3. This is a mandatory parameter and if it is not configured, it is not possible to enable BGP-AD using no shutdown.

  • Virtual Switching Instance (VSI) prefix — This identifies a specific instance of the VPLS. This must be unique within the VPLS instance, and is encoded using the 4 byte dotted decimal notation. Generally, the system address is used as the VSI prefix. If this parameter is not configured, then the system address is used automatically.

The VPLS-ID and VSI prefix for VPLS 3 on each PE is shown in VPLS instance with auto-provisioned SDPs.

The VPLS-ID and VSI prefix are concatenated to form a unique VSI-ID. In this case, PE-1 has a VSI-ID of 65536:3:192.0.2.1. This uniquely identifies the VPLS instance on each individual PE and is advertised as an L2-VPN BGP update.

A BGP-AD update is transmitted to all other PEs via the RR, as follows:

*A:PE-1# show router bgp routes l2-vpn rd 65536:3 hunt
===============================================================================
 BGP Router ID:192.0.2.1        AS:65536       Local AS:65536
===============================================================================
 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 L2VPN Routes
===============================================================================
---snip---
 
-------------------------------------------------------------------------------
RIB Out Entries
-------------------------------------------------------------------------------
Route Type     : AutoDiscovery
Route Dist.    : 65536:3
Prefix         : 192.0.2.1
Nexthop        : 192.0.2.1
To             : 192.0.2.6
Res. Nexthop   : n/a
Local Pref.    : 100                    Interface Name : NotAvailable
Aggregator AS  : None                   Aggregator     : None
Atomic Aggr.   : Not Atomic             MED            : 0
AIGP Metric    : None                   IGP Cost       : n/a
Connector      : None
Community      : target:65536:3 l2-vpn/vrf-imp:65536:3
Cluster        : No Cluster Members
Originator Id  : None                   Peer Router Id : 192.0.2.6
Origin         : IGP
AS-Path        : No As-Path
Route Tag      : 0
Neighbor-AS    : n/a
Orig Validation: N/A
Source Class   : 0                      Dest Class     : 0
 
-------------------------------------------------------------------------------
Routes : 4
===============================================================================

The preceding BGP update is transmitted by PE-1 and has route type auto-discovery.

In this L2-VPN update, the VPLS-ID is encoded as the L2-VPN extended community 65536:3.

The VSI is seen as the prefix 192.0.2.1. The combination of the VPLS-ID and the VSI forms the VSI-ID and uniquely identifies the VPLS instance within this PE router.

The next-hop is also encoded as the local system IP address 192.0.2.1, which allows remote PEs to identify a suitable transport tunnel to PE-1 and for the targeted-LDP peer for instantiating the SDP.

As can be seen within the update, the VPLS-ID 65536:3 is also used to determine the RT extended community and the route distinguisher (RD).

PE-2 configuration

On PE-2, VPLS 3 is created using pseudowire template 1, with VPLS-ID 65536:3 and VSI-ID prefix 192.0.2.2 (system IP address), as follows”

# on PE-2:
configure
    service
        vpls 3 name "VPLS3" customer 1 create
            bgp
                route-distinguisher 65536:3
                route-target export target:65536:3 import target:65536:3
                pw-template-binding 2 split-horizon-group "vpls-shg"
                    import-rt "target:65536:3"
                exit
            exit
            bgp-ad
                vpls-id 65536:3
                vsi-id
                    prefix 192.0.2.2
                exit
                no shutdown
            exit
            sap 1/1/4:3.0 create
            exit
            no shutdown
        exit

PE-3 configuration

On PE-3, VPLS 3 is created using pseudowire template 2, with VPLS-ID 65536:3—identical to the VPLS-ID of PE-1 and PE-2—and VSI-ID 192.0.2.3 (system IP address), as follows:

# on PE-3:
configure
    service
        vpls 3 name "VPLS3" customer 1 create
            bgp
                route-distinguisher 65536:3
                route-target export target:65536:3 import target:65536:3
                pw-template-binding 2 split-horizon-group "vpls-shg" 
                    import-rt "target:65536:3"
                exit
            exit
            bgp-ad
                vpls-id 65536:3
                vsi-id
                    prefix 192.0.2.3
                exit
                no shutdown
            exit
            sap 1/1/4:3.0 create
            exit
            no shutdown
        exit

PE-1 service operation verification

The following output shows that the service is operationally up on PE-1:

*A:PE-1# show service id 3 base
 
===============================================================================
Service Basic Information
===============================================================================
Service Id        : 3                   Vpn Id            : 0
Service Type      : VPLS                
---snip---

Admin State       : Up                  Oper State        : Up
MTU               : 1514 
SAP Count         : 1                   SDP Bind Count    : 2
---snip---
 
-------------------------------------------------------------------------------
Service Access & Destination Points
-------------------------------------------------------------------------------
Identifier                               Type         AdmMTU  OprMTU  Adm  Opr
-------------------------------------------------------------------------------
sap:1/1/4:3.0                            qinq         1522    1522    Up   Up
sdp:32766:4294967294 SB(192.0.2.2)       BgpAd        0       1556    Up   Up
sdp:32767:4294967295 SB(192.0.2.3)       BgpAd        0       1556    Up   Up
===============================================================================
* indicates that the corresponding row element may have been truncated.

As seen from the output, the service is operationally up, with the SAPs and SDPs also up. The SB flag indicates that the SDP is of type spoke-SDP (S flag) BGP (B flag).

BGP is used to discover the VPLS endpoints and exchange network reachability information. LDP is used to signal the pseudowires between the PEs.

LDP signaling occurs when each PE has discovered the endpoints of the VPLS instance. This compares with the use of the provisioned virtual circuit IDs used in an NMS provisioned VPLS instances as per RFC 4762.

The ability of PE-1 to reach the other PE routers with VSIs within the VPLS instance is verified from the following L2-route table:

*A:PE-1# show service l2-route-table bgp-ad
 
========================================================================
Services: L2 Route Information - Summary
========================================================================
Svc Id     L2-Routes (RD-Prefix)                 Next Hop        Origin
               Sdp Bind Id                           PW Temp Id
------------------------------------------------------------------------
3          *65536:3-192.0.2.2                    192.0.2.2       BGP-L2
               32766:4294967294                      2
3          *65536:3-192.0.2.3                    192.0.2.3       BGP-L2
               32767:4294967295                      2
------------------------------------------------------------------------
No. of L2 Route Entries: 2
========================================================================

This output shows the presence of the signaled pseudowire SDPs. SDPs from PE-1 to PE-2 and PE-3 are signaled using LDP Forwarding Equivalence Class (FEC) Element 129.

Each PE router uses targeted LDP to signal the local and remote endpoints. If there is an endpoint match, then SDPs are instantiated. This compares with the use of LDP for NMS provisioned SDPs, which uses virtual circuit IDs to signal pseudowires using LDP FEC Element 128.

In order to signal the SDPs, the following parameters are required:

  1. Attachment Group Identifier (AGI): this is used to carry the VPLS-ID of the local PE router VPLS instance. The VPLS-ID must be identical for all PEs in the same VPLS instance.

  2. Source Attachment Individual Identifier (SAII) and Target Attachment Individual Identifier (TAII): these use AII type 1 (RFC 4446) and are used to carry the NLRI (VSI-ID minus the RD) of the remote PE router VPLS instance.

The AGI for each PE must be identical. SAII and TAII must be different.

The following shows the service LDP bindings for VPLS 3 on PE-1:

*A:PE-1# show router ldp bindings services service-id 3
 
===============================================================================
LDP Bindings (IPv4 LSR ID 192.0.2.1)
             (IPv6 LSR ID ::)
===============================================================================
Label Status:
        U - Label In Use, N - Label Not In Use, W - Label Withdrawn
        S - Status Signaled Up,  D - Status Signaled Down, e - Label ELC
        WP - Label Withdraw Pending, BU - Alternate For Fast Re-Route
Service Type:
        E - Epipe Service, V - VPLS Service, M - Mirror Service
        A - Apipe Service, F - Fpipe Service, I - IES Service, R - VPRN service
        P - Ipipe Service, C - Cpipe Service
FEC Flags:
        LF - Lower FEC, UF - Upper FEC, M - Community Mismatch,
        BA - ASBR Backup FEC
===============================================================================
LDP Service FEC 128 Bindings
===============================================================================
Type                                          VCId       SDPId             LMTU
Peer                                          SvcId      IngLbl            RMTU
                                                         EgrLbl
-------------------------------------------------------------------------------
No Matching Entries Found
===============================================================================
 
===============================================================================
LDP Service FEC 129 Bindings
===============================================================================
SAII                                            AGII        IngLbl         LMTU
TAII                                            Type        EgrLbl         RMTU
Peer                                            SvcId       SDPId
-------------------------------------------------------------------------------
192.0.2.1                                       1,8:020A00* 524279U        1500
192.0.2.2                                       V-Eth       524278S        1500
192.0.2.2:0                                     3           32766
 
192.0.2.1                                       1,8:020A00* 524280U        1500
192.0.2.3                                       V-Eth       524280S        1500
192.0.2.3:0                                     3           32767
 
-------------------------------------------------------------------------------
No. of FEC 129s: 2
===============================================================================
* indicates that the corresponding row element may have been truncated.

This shows the two T-LDP bindings for PE-1 toward PE-2 and PE-3 for VPLS 3. The label bindings from this LDP output is identical to the SDP bindings output that follows. The following command can be used to list the SDP IDs and the SDP label bindings:

*A:PE-1# show service id 3 sdp
 
===============================================================================
Services: Service Destination Points
===============================================================================
SdpId            Type     Far End addr    Adm     Opr       I.Lbl     E.Lbl
-------------------------------------------------------------------------------
32766:4294967294 BgpAd    192.0.2.2       Up      Up        524279    524278
32767:4294967295 BgpAd    192.0.2.3       Up      Up        524280    524280
-------------------------------------------------------------------------------
Number of SDPs : 2
-------------------------------------------------------------------------------
===============================================================================

The SDP ID for the auto-provisioned SDP toward PE-2 is 32766, the SDP ID toward PE-3 is 32767.

The actual AGI, SAII, and TAII values are seen in the following detailed SDP output.

  • AGI — 65536:3

  • SAII — Local system IP address 192.0.2.1

  • TAII — Remote system IP address 192.0.2.2 or 192.0.2.3

    
    *A:PE-1# show service id 3 sdp 32767:4294967295 detail
     
    ===============================================================================
    Service Destination Point (Sdp Id : 32767:4294967295) Details
    ===============================================================================
    -------------------------------------------------------------------------------
     Sdp Id 32767:4294967295  -(192.0.2.3)
    -------------------------------------------------------------------------------
    Description     : (Not Specified)
    SDP Id             : 32767:4294967295         Type              : BgpAd
    PW-Template Id     : 2
    AGI                : 65536:3                  SDP Bind Source   : bgp-l2vpn
    Local AII          : 192.0.2.1
    Remote AII         : 192.0.2.3
    Split Horiz Grp    : vpls-shg
    Etree Root Leaf Tag: Disabled                 Etree Leaf AC     : Disabled
    VC Type            : Ether                    VC Tag            : n/a
    Admin Path MTU     : 0                        Oper Path MTU     : 1556
    Delivery           : MPLS
    Far End            : 192.0.2.3                Tunnel Far End    : n/a
    Oper Tunnel Far End: 192.0.2.3
    LSP Types          : LDP/BGP
    ---snip---
    

PE-2 service operation verification

For completeness, the following shows that the VPLS service is operationally up on PE-2.

*A:PE-2# show service id 3 base
 
===============================================================================
Service Basic Information
===============================================================================
Service Id        : 3                   Vpn Id            : 0
Service Type      : VPLS                
---snip---
 
Admin State       : Up                  Oper State        : Up
MTU               : 1514 
SAP Count         : 1                   SDP Bind Count    : 2
---snip---
 
-------------------------------------------------------------------------------
Service Access & Destination Points
-------------------------------------------------------------------------------
Identifier                               Type         AdmMTU  OprMTU  Adm  Opr
-------------------------------------------------------------------------------
sap:1/1/4:3.0                            qinq         1522    1522    Up   Up
sdp:32766:4294967294 SB(192.0.2.3)       BgpAd        0       1556    Up   Up
sdp:32767:4294967295 SB(192.0.2.1)       BgpAd        0       1556    Up   Up
===============================================================================
* indicates that the corresponding row element may have been truncated.
*A:PE-2# show service l2-route-table bgp-ad
 
========================================================================
Services: L2 Route Information - Summary
========================================================================
Svc Id     L2-Routes (RD-Prefix)                 Next Hop        Origin
               Sdp Bind Id                           PW Temp Id
------------------------------------------------------------------------
3          *65536:3-192.0.2.1                    192.0.2.1       BGP-L2
               32767:4294967295                      2
3          *65536:3-192.0.2.3                    192.0.2.3       BGP-L2
               32766:4294967294                      2
------------------------------------------------------------------------
No. of L2 Route Entries: 2
========================================================================
*A:PE-2# show router ldp bindings services service-id 3
 
===============================================================================
LDP Bindings (IPv4 LSR ID 192.0.2.2)
             (IPv6 LSR ID ::)
===============================================================================
Label Status:
        U - Label In Use, N - Label Not In Use, W - Label Withdrawn
        S - Status Signaled Up,  D - Status Signaled Down, e - Label ELC
        WP - Label Withdraw Pending, BU - Alternate For Fast Re-Route
Service Type:
        E - Epipe Service, V - VPLS Service, M - Mirror Service
        A - Apipe Service, F - Fpipe Service, I - IES Service, R - VPRN service
        P - Ipipe Service, C - Cpipe Service
FEC Flags:
        LF - Lower FEC, UF - Upper FEC, M - Community Mismatch,
        BA - ASBR Backup FEC
===============================================================================
LDP Service FEC 128 Bindings
===============================================================================
Type                                          VCId       SDPId             LMTU
Peer                                          SvcId      IngLbl            RMTU
                                                         EgrLbl
-------------------------------------------------------------------------------
No Matching Entries Found
===============================================================================
 
===============================================================================
LDP Service FEC 129 Bindings
===============================================================================
SAII                                            AGII        IngLbl         LMTU
TAII                                            Type        EgrLbl         RMTU
Peer                                            SvcId       SDPId
-------------------------------------------------------------------------------
192.0.2.2                                       1,8:020A00* 524278U        1500
192.0.2.1                                       V-Eth       524279S        1500
192.0.2.1:0                                     3           32767
 
192.0.2.2                                       1,8:020A00* 524277U        1500
192.0.2.3                                       V-Eth       524279S        1500
192.0.2.3:0                                     3           32766
 
-------------------------------------------------------------------------------
No. of FEC 129s: 2
===============================================================================
* indicates that the corresponding row element may have been truncated.
*A:PE-2# show service id 3 sdp
 
===============================================================================
Services: Service Destination Points
===============================================================================
SdpId            Type     Far End addr    Adm     Opr       I.Lbl     E.Lbl
-------------------------------------------------------------------------------
32766:4294967294 BgpAd    192.0.2.3       Up      Up        524277    524279
32767:4294967295 BgpAd    192.0.2.1       Up      Up        524278    524279
-------------------------------------------------------------------------------
Number of SDPs : 2
-------------------------------------------------------------------------------
===============================================================================

PE-3 service operation verification

On PE-3, the VPLS service is operationally up with the following BGP-AD SDPs:

*A:PE-3# show service id 3 base
 
===============================================================================
Service Basic Information
===============================================================================
Service Id        : 3                   Vpn Id            : 0
Service Type      : VPLS                
---snip---
 
Admin State       : Up                  Oper State        : Up
MTU               : 1514 
SAP Count         : 1                   SDP Bind Count    : 2
---snip---
 
-------------------------------------------------------------------------------
Service Access & Destination Points
-------------------------------------------------------------------------------
Identifier                               Type         AdmMTU  OprMTU  Adm  Opr
-------------------------------------------------------------------------------
sap:1/1/4:3.0                            qinq         1522    1522    Up   Up
sdp:32766:4294967294 SB(192.0.2.2)       BgpAd        0       1556    Up   Up
sdp:32767:4294967295 SB(192.0.2.1)       BgpAd        0       1556    Up   Up
===============================================================================
* indicates that the corresponding row element may have been truncated.
*A:PE-3# show service l2-route-table bgp-ad
 
========================================================================
Services: L2 Route Information - Summary
========================================================================
Svc Id     L2-Routes (RD-Prefix)                 Next Hop        Origin
               Sdp Bind Id                           PW Temp Id
------------------------------------------------------------------------
3          *65536:3-192.0.2.1                    192.0.2.1       BGP-L2
               32767:4294967295                      2
3          *65536:3-192.0.2.2                    192.0.2.2       BGP-L2
               32766:4294967294                      2
------------------------------------------------------------------------
No. of L2 Route Entries: 2
========================================================================
*A:PE-3# show router ldp bindings services service-id 3
 
===============================================================================
LDP Bindings (IPv4 LSR ID 192.0.2.3)
             (IPv6 LSR ID ::)
===============================================================================
Label Status:
        U - Label In Use, N - Label Not In Use, W - Label Withdrawn
        S - Status Signaled Up,  D - Status Signaled Down, e - Label ELC
        WP - Label Withdraw Pending, BU - Alternate For Fast Re-Route
Service Type:
        E - Epipe Service, V - VPLS Service, M - Mirror Service
        A - Apipe Service, F - Fpipe Service, I - IES Service, R - VPRN service
        P - Ipipe Service, C - Cpipe Service
FEC Flags:
        LF - Lower FEC, UF - Upper FEC, M - Community Mismatch,
        BA - ASBR Backup FEC
===============================================================================
LDP Service FEC 128 Bindings
===============================================================================
Type                                          VCId       SDPId             LMTU
Peer                                          SvcId      IngLbl            RMTU
                                                         EgrLbl
-------------------------------------------------------------------------------
No Matching Entries Found
===============================================================================
 
===============================================================================
LDP Service FEC 129 Bindings
===============================================================================
SAII                                            AGII        IngLbl         LMTU
TAII                                            Type        EgrLbl         RMTU
Peer                                            SvcId       SDPId
-------------------------------------------------------------------------------
192.0.2.3                                       1,8:020A00* 524280U        1500
192.0.2.1                                       V-Eth       524280S        1500
192.0.2.1:0                                     3           32767
 
192.0.2.3                                       1,8:020A00* 524279U        1500
192.0.2.2                                       V-Eth       524277S        1500
192.0.2.2:0                                     3           32766
 
-------------------------------------------------------------------------------
No. of FEC 129s: 2
===============================================================================
* indicates that the corresponding row element may have been truncated.
*A:PE-3# show service id 3 sdp
 
===============================================================================
Services: Service Destination Points
===============================================================================
SdpId            Type     Far End addr    Adm     Opr       I.Lbl     E.Lbl
-------------------------------------------------------------------------------
32766:4294967294 BgpAd    192.0.2.2       Up      Up        524279    524277
32767:4294967295 BgpAd    192.0.2.1       Up      Up        524280    524280
-------------------------------------------------------------------------------
Number of SDPs : 2
-------------------------------------------------------------------------------
===============================================================================

BGP AD using pre-provisioned SDPs

It is possible to configure BGP-AD instances that use RSVP transport tunnels. In this case, the LSPs and SDPs must be manually created.

Figure 3. VPLS instance using pre-provisioned SDPs

VPLS instance using pre-provisioned SDPs shows a VPLS instance configured across three PE routers as before.

The SDP configurations for the three PEs are as follows:

# on PE-1:
configure 
    service
        sdp 12 mpls create
            description "RSVP-based SDP from PE-1 to PE-2"
            far-end 192.0.2.2
            lsp "LSP-PE-1-PE-2"
            no shutdown
        exit
        sdp 13 mpls create
            description "RSVP-based SDP from PE-1 to PE-3"
            far-end 192.0.2.3
            lsp "LSP-PE-1-PE-3"
            no shutdown
        exit 
# on PE-2:
configure
    service
        sdp 21 mpls create
            description "RSVP-based SDP from PE-2 to PE-1"
            far-end 192.0.2.1
            lsp "LSP-PE-2-PE-1"
            no shutdown
        exit
        sdp 23 mpls create
            description "RSVP-based SDP from PE-2 to PE-3"
            far-end 192.0.2.3
            lsp "LSP-PE-2-PE-3"
            no shutdown
        exit 
# on PE-3:
configure
    service
        sdp 31 mpls create
            description "RSVP-based SDP from PE-3 to PE-1"
            far-end 192.0.2.1
            lsp "LSP-PE-3-PE-1"
            no shutdown
        exit
        sdp 32 mpls create
            description "RSVP-based SDP from PE-3 to PE-2"
            far-end 192.0.2.2
            lsp "LSP-PE-3-PE-2"
            no shutdown
        exit 

The pw-template that is to be used within each VPLS instance must be provisioned on all PEs and must use the keyword use-provisioned-sdp. The pw-template is configured on all PEs with the following command:

# on PE-1, PE-2, PE-3:
configure 
    service 
        pw-template 3 name "PW3" use-provisioned-sdp create
        exit

The following output shows the configuration required for a VPLS service using a pseudowire template configured for pre-provisioned RSVP SDPs.

# on PE-1:
configure
    service
        vpls 4 name "VPLS4" customer 1 create
            bgp
                route-distinguisher 65536:4
                route-target export target:65536:4 import target:65536:4
                pw-template-binding 3 split-horizon-group "vpls-shg"
                    import-rt "target:65536:4"
                exit
            exit
            bgp-ad
                vpls-id 65536:4
                vsi-id
                    prefix 192.0.2.1
                exit
                no shutdown
            exit
            sap 1/1/4:4.0 create
            exit
            no shutdown
        exit

Similarly, on PE-2 the configuration is as follows:

# on PE-2:
configure
    service
        vpls 4 name "VPLS4" customer 1 create
            bgp
                route-distinguisher 65536:4
                route-target export target:65536:4 import target:65536:4
                pw-template-binding 3 split-horizon-group "vpls-shg" 
                    import-rt "target:65536:4"
                exit
            exit
            bgp-ad
                vpls-id 65536:4
                vsi-id
                    prefix 192.0.2.2
                exit
                no shutdown
            exit
            sap 1/1/4:4.0 create
            exit
            no shutdown
        exit

On PE-3, VPLS 4 is configured as follows:

# on PE-3:
configure
    service
        vpls 4 name "VPLS4" customer 1 create
            bgp
                route-distinguisher 65536:4
                route-target export target:65536:4 import target:65536:4
                pw-template-binding 3 split-horizon-group "vpls-shg" 
                    import-rt "target:65536:4"
                exit
            exit
            bgp-ad
                vpls-id 65536:4
                vsi-id
                    prefix 192.0.2.3
                exit
                no shutdown
            exit
            sap 1/1/4:4.0 create
            exit
            no shutdown
        exit

The following output shows that the service is operationally up on PE-1.

*A:PE-1# show service id 4 base
 
===============================================================================
Service Basic Information
===============================================================================
Service Id        : 4                   Vpn Id            : 0
Service Type      : VPLS                
---snip---
 
Admin State       : Up                  Oper State        : Up
MTU               : 1514 
SAP Count         : 1                   SDP Bind Count    : 2
---snip---
 
-------------------------------------------------------------------------------
Service Access & Destination Points
-------------------------------------------------------------------------------
Identifier                               Type         AdmMTU  OprMTU  Adm  Opr
-------------------------------------------------------------------------------
sap:1/1/4:4.0                            qinq         1522    1522    Up   Up
sdp:12:4294967293 S(192.0.2.2)           BgpAd        0       1556    Up   Up
sdp:13:4294967292 S(192.0.2.3)           BgpAd        0       1556    Up   Up
===============================================================================
* indicates that the corresponding row element may have been truncated.

The SDP identifiers are the pre-provisioned SDPs: SDP 12 and 13.

The following command shows that the service is operationally up on PE-2.

*A:PE-2# show service id 4 base
 
===============================================================================
Service Basic Information
===============================================================================
Service Id        : 4                   Vpn Id            : 0
Service Type      : VPLS                
---snip---

Admin State       : Up                  Oper State        : Up
MTU               : 1514 
SAP Count         : 1                   SDP Bind Count    : 2
---snip---

-------------------------------------------------------------------------------
Service Access & Destination Points
-------------------------------------------------------------------------------
Identifier                               Type         AdmMTU  OprMTU  Adm  Opr
-------------------------------------------------------------------------------
sap:1/1/4:4.0                            qinq         1522    1522    Up   Up
sdp:21:4294967293 S(192.0.2.1)           BgpAd        0       1556    Up   Up
sdp:23:4294967292 S(192.0.2.3)           BgpAd        0       1556    Up   Up
===============================================================================
* indicates that the corresponding row element may have been truncated.

The following command shows that the service is operationally up on PE-3.

*A:PE-3# show service id 4 base
 
===============================================================================
Service Basic Information
===============================================================================
Service Id        : 4                   Vpn Id            : 0
Service Type      : VPLS                
---snip---
 
Admin State       : Up                  Oper State        : Up
MTU               : 1514 
SAP Count         : 1                   SDP Bind Count    : 2
---snip---
 
-------------------------------------------------------------------------------
Service Access & Destination Points
-------------------------------------------------------------------------------
Identifier                               Type         AdmMTU  OprMTU  Adm  Opr
-------------------------------------------------------------------------------
sap:1/1/4:4.0                            qinq         1522    1522    Up   Up
sdp:31:4294967293 S(192.0.2.1)           BgpAd        0       1556    Up   Up
sdp:32:4294967292 S(192.0.2.2)           BgpAd        0       1556    Up   Up
===============================================================================
* indicates that the corresponding row element may have been truncated.

Conclusion

BGP-AD coupled with LDP pseudowire signaling allows the delivery of L2-VPN services to customers where BGP is commonly used. This example shows the configuration of BGP-AD together with the associated show outputs which can be used for verification and troubleshooting.