Inter-AS Model C for VLL
This chapter describes advanced inter-AS model C for Virtual Leased Line (VLL) configurations.
Topics in this chapter include:
Applicability
This chapter was initially written for SR OS Release 8.0.R4. The CLI in the current edition corresponds to SR OS Release 20.10.R2.
Overview
SR OS supports RFC 3107, Carrying Label Information in BGP-4, including VLL/VPLS. BGP SDPs can also be used with PBB-VPLS services.
Internet service providers are looking for mechanisms to implement the VLL and VPLS services across Autonomous Systems (ASs). Service providers may have inter-AS operation as a consequence of delivering inter-provider VLL/VPLS or because they use multiple ASs as a result of acquisitions and mergers.
The objective of this chapter is to describe the interconnection of VLL services across multiple ASs, using inter-AS model C. Inter-AS Model C involves eBGP redistribution of internal system addresses to the neighboring AS using labeled IPv4 routes.
Example topology
Example topology – Inter-AS model C for VLL shows the example topology used for Inter-AS Model C VLL.
The example topology shown in Example topology – Inter-AS model C for VLL consists of three sites in different ASs with each site using SR OS nodes.
AS 64500 contains PE-1 and PE-2, AS 64501 contains PE-3, and AS 64502 contains PE-4 and PE-5. There is a business customer with two remote locations, Site A and Site B, with Customer Edge (CE) devices CE-1 connected to the AS 64500 via PE-1 and CE-5 connected to the AS 64502 via PE-5. A VLL Epipe service is configured between PE-1 and PE-5 to connect site A and site B.
Configuration
This section describes all of the relevant configuration tasks for the detailed setup shown in Network setup configuration. In this particular example, the following protocols are assumed to be already configured.
IS-IS as the IGP with all the nodes being level Level1/Level 2.
LDP as the MPLS protocol to signal the transport tunnels within AS 64500 and AS 64502.
Figure 3. Network setup configuration 
BGP configuration
A BGP tunnel must be established between PE-1 and PE-5, therefore, labeled BGP routes must be exchanged for prefixes 192.0.2.1/32 and 192.0.2.5/32 across the ASs. The following shows the BGP configuration — iBGP and eBGP — required for the PE routers to implement an Inter-AS VLL.
The BGP configuration on PE-3 in AS 64501 is as follows:
# on PE-3:
configure
router Base
autonomous-system 64501
bgp
rapid-withdrawal
split-horizon
group "EBGP"
local-as 64501
neighbor 192.168.23.1
family label-ipv4
peer-as 64500
exit
neighbor 192.168.34.2
family label-ipv4
peer-as 64502
exit
exit
exit
The address family label-ipv4 must be configured so that MPLS labels are carried along with MP-BGP Network Layer Reachability Information (NLRIs), see chapter Separate BGP RIBs for Labeled Routes. The setting split-horizon is optional and prevents that a received route is sent back to the originator, which might result in multiple routes for a certain prefix.
To export the prefixes of the nodes where the Epipe is configured (PE-1 and PE-5) to another AS, a common scenario is to advertise the prefix to be exported within the AS as labeled BGP. Therefore, an export policy is defined for prefix192.0.2.1/32 on PE-1 and this prefix will be advertised to the ASBR in AS 64500, in this case to PE-2.
On PE-2, the labeled BGP route for prefix 192.0.2.1/32 is inactive, because the IGP route for that prefix is preferred. No export policy needs to be configured in the Autonomous System Border Router (ASBR) PE-2 for the EBGP session with PE-3 in AS 64501. Rather, the setting advertise-inactive will allow the inactive labeled BGP routes from AS 64500 to be advertised to PE-3 in AS 64501.
Likewise, an export policy will be configured on PE-5 to advertise prefix 192.0.2.5/32 to ASBR PE-4 in AS 64502. On PE-4, BGP is configured with advertise-inactive to advertise the labeled BGP route to its EBGP peer, PE-3.
The advantage of this approach is that labeled BGP is used end-to-end between PE-1 and PE-5 and no IGP routes are to be redistributed into BGP, which would be the case if no local BGP labeled routes were advertised within AS 64500 or AS 64502 and only IGP routes were defined within these ASs.
The ASBRs PE-2, PE-3, and PE-4 will swap the BGP labels. PE-3 will advertise the labeled BGP routes learned from AS 64500 to AS 64502 and vice versa and the ASBRs will advertise these labeled routes for remote PE prefixes to their BGP peers. Eventually, PE-1 will have learned a labeled BGP route for prefix 192.0.2.5/32 and PE-5 will have learned a labeled BGP route for prefix 192.0.2.1/32 and a VLL Epipe can be established between PE-1 and PE-5.
The BGP configuration of ASBR PE-2 in AS 64500 is as follows:
# on PE-2:
configure
router Base
autonomous-system 64500
bgp
rapid-withdrawal
split-horizon
group "EBGP"
local-as 64500
neighbor 192.168.23.2
family label-ipv4
peer-as 64501
advertise-inactive
exit
exit
group "IBGP"
neighbor 192.0.2.1
family label-ipv4
next-hop-self
peer-as 64500
exit
exit
exit
The BGP configuration of ASBR PE-4 in AS 64502 is as follows:
# on PE-4:
configure
router Base
autonomous-system 64502
bgp
rapid-withdrawal
split-horizon
group "EBGP"
local-as 64502
neighbor 192.168.34.1
family label-ipv4
peer-as 64501
advertise-inactive
exit
exit
group "IBGP"
neighbor 192.0.2.5
family label-ipv4
next-hop-self
peer-as 64502
exit
exit
exit
PE-1 and PE-5 are the PEs to which the CEs are connected in AS 64500 and AS 64502. PE-1 and PE-5 advertise their system prefixes as labeled BGP routes to their BGP peers within the AS.
The BGP configuration of PE-1 is as follows:
# on PE-1:
configure
router Base
autonomous-system 64500
bgp
rapid-withdrawal
split-horizon
group "IBGP"
export "export-PE-1"
neighbor 192.0.2.2
family label-ipv4
next-hop-self
peer-as 64500
exit
exit
exit
The BGP configuration of PE-5 in AS 64502 is as follows:
# on PE-5:
configure
router Base
autonomous-system 64502
bgp
rapid-withdrawal
split-horizon
group "IBGP"
export "export-PEsys"
neighbor 192.0.2.4
family label-ipv4
next-hop-self
peer-as 64502
exit
exit
exit
Policy configuration
The export policies on PE-1 and PE-5 advertise the system addresses to the remote AS.
The export policy on PE-1 has a prefix list that only contains prefix 192.0.2.1/32 as follows:
# on PE-1:
configure
router Base
policy-options
begin
prefix-list "PE-1"
prefix 192.0.2.1/32 exact
exit
policy-statement "export-PE-1"
entry 10
from
prefix-list "PE-1"
exit
action accept
exit
exit
exit
commit
A similar export policy can be configured for prefix 192.0.2.5/32 on PE-5. However, the export policy on PE-5 is slightly different: the policy has a prefix list that can be applied for prefixes on multiple PEs, but in this case, only prefix 192.0.2.5/32 will be exported:
# on PE-5:
configure
router Base
policy-options
begin
prefix-list "PEsys"
prefix 192.0.2.0/29 longer
exit
policy-statement "export-PEsys"
entry 10
from
protocol direct
prefix-list "PEsys"
exit
action accept
exit
exit
exit
commit
The same policy could have been applied on PE-1.
Service configuration
Once BGP is configured, the configuration requires the service to be defined (Epipe 1). The focus here is a VLL service, however, it is also possible to have a similar configuration with VPLS services.
The following shows the service level configuration on PE-1:
# on PE-1:
configure
service
sdp 15 mpls create
far-end 192.0.2.5
bgp-tunnel
no shutdown
exit
epipe 1 name "Epipe 1" customer 1 create
description "Tunnel-PE-1-PE-5"
sap 1/1/3:1 create
exit
spoke-sdp 15:1 create
exit
no shutdown
exit
The following CLI shows the service level configuration on PE-5:
# on PE-5:
configure
service
sdp 51 mpls create
far-end 192.0.2.1
bgp-tunnel
no shutdown
exit
epipe 1 name "Epipe 1" customer 1 create
description "Tunnel-PE-5-PE-1"
sap 1/1/3:1 create
exit
spoke-sdp 51:1 create
exit
no shutdown
exit
Show commands and troubleshooting
On PE-5, BGP tunnels exist to the remote AS system addresses that are using LDP as a transport mechanism and the configuration of end-to-end SDPs over which T-LDP service labels are exchanged.
In the following sections, the same commands are launched on the nodes in the following order: first on PE-1 and PE-5; then on PE-3, and finally, on PE-2 and PE-4.
Show commands and troubleshooting on PE-1
The following shows information about SDP 15 on PE-1:
*A:PE-1# show service sdp
============================================================================
Services: Service Destination Points
============================================================================
SdpId AdmMTU OprMTU Far End Adm Opr Del LSP Sig
----------------------------------------------------------------------------
15 0 1552 192.0.2.5 Up Up MPLS B TLDP
----------------------------------------------------------------------------
Number of SDPs : 1
----------------------------------------------------------------------------
Legend: R = RSVP, L = LDP, B = BGP, M = MPLS-TP, n/a = Not Applicable
I = SR-ISIS, O = SR-OSPF, T = SR-TE, F = FPE
============================================================================
On PE-1, the VLL Epipe service is up, as follows:
*A:PE-1# show service service-using
===============================================================================
Services
===============================================================================
ServiceId Type Adm Opr CustomerId Service Name
-------------------------------------------------------------------------------
1 Epipe Up Up 1 Epipe 1
2147483648 IES Up Down 1 _tmnx_InternalIesService
2147483649 intVpls Up Down 1 _tmnx_InternalVplsService
-------------------------------------------------------------------------------
Matching Services : 3
-------------------------------------------------------------------------------
===============================================================================
Two LDP sessions have been established from PE-1: a link LDP session with neighbor PE-2 in AS 64500 and a targeted LDP session with PE-5 in AS 64502, as follows:
*A:PE-1# show router ldp session ipv4
==============================================================================
LDP IPv4 Sessions
==============================================================================
Peer LDP Id Adj Type State Msg Sent Msg Recv Up Time
------------------------------------------------------------------------------
192.0.2.2:0 Link Established 109 111 0d 00:04:31
192.0.2.5:0 Targeted Established 21 23 0d 00:01:20
------------------------------------------------------------------------------
No. of IPv4 Sessions: 2
==============================================================================
The route table on PE-1 shows that the system IP address of PE-5 is reachable using a BGP tunnel:
*A:PE-1# show router route-table
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags] Type Proto Age Pref
Next Hop[Interface Name] Metric
-------------------------------------------------------------------------------
192.0.2.1/32 Local Local 00h06m03s 0
system 0
192.0.2.2/32 Remote ISIS 00h04m48s 15
192.168.12.2 10
192.0.2.5/32 Remote BGP_LABEL 00h01m46s 170
192.0.2.2 (tunneled) 10
192.168.12.0/30 Local Local 00h06m03s 0
int-PE-1-PE-2 0
-------------------------------------------------------------------------------
No. of Routes: 4
Flags: n = Number of times nexthop is repeated
B = BGP backup route available
L = LFA nexthop available
S = Sticky ECMP requested
===============================================================================
The following tunnel-table on PE-1 shows the details of the LDP, SDP, and BGP tunnels.
*A:PE-1# show router tunnel-table
===============================================================================
IPv4 Tunnel Table (Router: Base)
===============================================================================
Destination Owner Encap TunnelId Pref Nexthop Metric
Color
-------------------------------------------------------------------------------
192.0.2.2/32 ldp MPLS 65537 9 192.168.12.2 10
192.0.2.5/32 sdp MPLS 15 5 192.0.2.5 0
192.0.2.5/32 bgp MPLS 262145 12 192.0.2.2 1000
-------------------------------------------------------------------------------
Flags: B = BGP or MPLS backup hop available
L = Loop-Free Alternate (LFA) hop available
E = Inactive best-external BGP route
k = RIB-API or Forwarding Policy backup hop
===============================================================================
The service details for Epipe 1 on PE-1 are as follows:
*A:PE-1# show service id 1 base
===============================================================================
Service Basic Information
===============================================================================
Service Id : 1 Vpn Id : 0
Service Type : Epipe
MACSec enabled : no
Name : Epipe 1
Description : Tunnel-PE-1-PE-5
Customer Id : 1 Creation Origin : manual
Last Status Change: 01/21/2021 16:01:07
Last Mgmt Change : 01/21/2021 16:00:53
Test Service : No
Admin State : Up Oper State : Up
MTU : 1514
Vc Switching : False
SAP Count : 1 SDP Bind Count : 1
Per Svc Hashing : Disabled
Vxlan Src Tep Ip : N/A
Force QTag Fwd : Disabled
Oper Group : <none>
-------------------------------------------------------------------------------
Service Access & Destination Points
-------------------------------------------------------------------------------
Identifier Type AdmMTU OprMTU Adm Opr
-------------------------------------------------------------------------------
sap:1/1/3:1 q-tag 1518 1518 Up Up
sdp:15:1 S(192.0.2.5) Spok 0 1552 Up Up
===============================================================================
ICMP is used to verify the IP connectivity from PE-1 to the system IP address of PE-5:
*A:PE-1# ping 192.0.2.5
PING 192.0.2.5 56 data bytes
64 bytes from 192.0.2.5: icmp_seq=1 ttl=64 time=1.91ms.
64 bytes from 192.0.2.5: icmp_seq=2 ttl=64 time=2.06ms.
64 bytes from 192.0.2.5: icmp_seq=3 ttl=64 time=2.02ms.
64 bytes from 192.0.2.5: icmp_seq=4 ttl=64 time=2.01ms.
64 bytes from 192.0.2.5: icmp_seq=5 ttl=64 time=2.02ms.
---- 192.0.2.5 PING Statistics ----
5 packets transmitted, 5 packets received, 0.00% packet loss
round-trip min = 1.91ms, avg = 2.01ms, max = 2.06ms, stddev = 0.050ms
Show commands and troubleshooting on PE-5
The same commands on PE-5 result in the following output:
*A:PE-5# show service sdp
============================================================================
Services: Service Destination Points
============================================================================
SdpId AdmMTU OprMTU Far End Adm Opr Del LSP Sig
----------------------------------------------------------------------------
51 0 1552 192.0.2.1 Up Up MPLS B TLDP
----------------------------------------------------------------------------
Number of SDPs : 1
----------------------------------------------------------------------------
Legend: R = RSVP, L = LDP, B = BGP, M = MPLS-TP, n/a = Not Applicable
I = SR-ISIS, O = SR-OSPF, T = SR-TE, F = FPE
============================================================================
*A:PE-5# show service service-using
===============================================================================
Services
===============================================================================
ServiceId Type Adm Opr CustomerId Service Name
-------------------------------------------------------------------------------
1 Epipe Up Up 1 Epipe 1
2147483648 IES Up Down 1 _tmnx_InternalIesService
2147483649 intVpls Up Down 1 _tmnx_InternalVplsService
-------------------------------------------------------------------------------
Matching Services : 3
-------------------------------------------------------------------------------
===============================================================================
*A:PE-5# show router ldp session ipv4
==============================================================================
LDP IPv4 Sessions
==============================================================================
Peer LDP Id Adj Type State Msg Sent Msg Recv Up Time
------------------------------------------------------------------------------
192.0.2.1:0 Targeted Established 52 53 0d 00:04:07
192.0.2.4:0 Link Established 185 188 0d 00:07:57
------------------------------------------------------------------------------
No. of IPv4 Sessions: 2
==============================================================================
*A:PE-5# show router route-table
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags] Type Proto Age Pref
Next Hop[Interface Name] Metric
-------------------------------------------------------------------------------
192.0.2.1/32 Remote BGP_LABEL 00h05m47s 170
192.0.2.4 (tunneled) 10
192.0.2.4/32 Remote ISIS 00h08m13s 15
192.168.45.1 10
192.0.2.5/32 Local Local 00h08m19s 0
system 0
192.168.45.0/30 Local Local 00h08m19s 0
int-PE-5-PE-4 0
-------------------------------------------------------------------------------
No. of Routes: 4
Flags: n = Number of times nexthop is repeated
B = BGP backup route available
L = LFA nexthop available
S = Sticky ECMP requested
===============================================================================
*A:PE-5# show router tunnel-table
===============================================================================
IPv4 Tunnel Table (Router: Base)
===============================================================================
Destination Owner Encap TunnelId Pref Nexthop Metric
Color
-------------------------------------------------------------------------------
192.0.2.1/32 sdp MPLS 51 5 192.0.2.1 0
192.0.2.1/32 bgp MPLS 262145 12 192.0.2.4 1000
192.0.2.4/32 ldp MPLS 65537 9 192.168.45.1 10
-------------------------------------------------------------------------------
Flags: B = BGP or MPLS backup hop available
L = Loop-Free Alternate (LFA) hop available
E = Inactive best-external BGP route
k = RIB-API or Forwarding Policy backup hop
===============================================================================
*A:PE-5# show service id 1 base
===============================================================================
Service Basic Information
===============================================================================
Service Id : 1 Vpn Id : 0
Service Type : Epipe
MACSec enabled : no
Name : Epipe 1
Description : Tunnel-PE-5-PE-1
Customer Id : 1 Creation Origin : manual
Last Status Change: 01/21/2021 16:01:07
Last Mgmt Change : 01/21/2021 16:00:49
Test Service : No
Admin State : Up Oper State : Up
MTU : 1514
Vc Switching : False
SAP Count : 1 SDP Bind Count : 1
Per Svc Hashing : Disabled
Vxlan Src Tep Ip : N/A
Force QTag Fwd : Disabled
Oper Group : <none>
-------------------------------------------------------------------------------
Service Access & Destination Points
-------------------------------------------------------------------------------
Identifier Type AdmMTU OprMTU Adm Opr
-------------------------------------------------------------------------------
sap:1/1/3:1 q-tag 1518 1518 Up Up
sdp:51:1 S(192.0.2.1) Spok 0 1552 Up Up
===============================================================================
*A:PE-5# ping 192.0.2.1
PING 192.0.2.1 56 data bytes
64 bytes from 192.0.2.1: icmp_seq=1 ttl=64 time=1.83ms.
64 bytes from 192.0.2.1: icmp_seq=2 ttl=64 time=2.06ms.
64 bytes from 192.0.2.1: icmp_seq=3 ttl=64 time=2.01ms.
64 bytes from 192.0.2.1: icmp_seq=4 ttl=64 time=2.08ms.
64 bytes from 192.0.2.1: icmp_seq=5 ttl=64 time=2.15ms.
---- 192.0.2.1 PING Statistics ----
5 packets transmitted, 5 packets received, 0.00% packet loss
round-trip min = 1.83ms, avg = 2.03ms, max = 2.15ms, stddev = 0.107ms
On PE-5, the BGP route to the system IP address of PE-1 can been seen with PE-4 as the next hop:
*A:PE-5# show router bgp routes label-ipv4
===============================================================================
BGP Router ID:192.0.2.5 AS:64502 Local AS:64502
===============================================================================
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 Routes
===============================================================================
Flag Network LocalPref MED
Nexthop (Router) Path-Id IGP Cost
As-Path Label
-------------------------------------------------------------------------------
u*>i 192.0.2.1/32 100 None
192.0.2.4 None 10
64501 64500 524285
-------------------------------------------------------------------------------
Routes : 1
===============================================================================
On PE-5, the FIB on slot 1 shows that the system IP address of PE-1 is reachable using BGP over an LDP transport to PE-4:
*A:PE-5# show router fib 1
===============================================================================
FIB Display
===============================================================================
Prefix [Flags] Protocol
NextHop
-------------------------------------------------------------------------------
192.0.2.1/32 BGP_LABEL
192.0.2.4 (Transport:LDP)
192.0.2.4/32 ISIS
192.168.45.1 (int-PE-5-PE-4)
192.0.2.5/32 LOCAL
192.0.2.5 (system)
192.168.45.0/30 LOCAL
192.168.45.0 (int-PE-5-PE-4)
-------------------------------------------------------------------------------
Total Entries : 4
-------------------------------------------------------------------------------
===============================================================================
Show commands on PE-3
The show commands on router PE-3 in AS 64501 are as follows:
*A:PE-3# 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
-------------------------------------------------------------------------------
192.168.23.1
Def. Instance 64500 22 0 00h09m12s 1/1/1 (Lbl-IPv4)
22 0
192.168.34.2
Def. Instance 64502 23 0 00h09m04s 1/1/1 (Lbl-IPv4)
25 0
-------------------------------------------------------------------------------
*A:PE-3# show router bgp routes label-ipv4
===============================================================================
BGP Router ID:192.0.2.3 AS:64501 Local AS:64501
===============================================================================
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 Routes
===============================================================================
Flag Network LocalPref MED
Nexthop (Router) Path-Id IGP Cost
As-Path Label
-------------------------------------------------------------------------------
u*>i 192.0.2.1/32 None None
192.168.23.1 None 0
64500 524285
u*>i 192.0.2.5/32 None None
192.168.34.2 None 0
64502 524284
-------------------------------------------------------------------------------
Routes : 2
===============================================================================
The BGP labels are swapped at PE-3, as follows:
*A:PE-3# 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
-------------------------------------------------------------------------------
192.168.23.1 524285 524287 External
192.168.34.2 524284 524286 External
-------------------------------------------------------------------------------
Total Labels allocated: 2
===============================================================================
The routing table on PE-3 includes BGP labeled routes to PE-1 and PE-5, as follows:
*A:PE-3# show router route-table
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags] Type Proto Age Pref
Next Hop[Interface Name] Metric
-------------------------------------------------------------------------------
192.0.2.1/32 Remote BGP_LABEL 00h10m02s 170
192.168.23.1 0
192.0.2.3/32 Local Local 00h12m42s 0
system 0
192.0.2.5/32 Remote BGP_LABEL 00h09m23s 170
192.168.34.2 0
192.168.23.0/30 Local Local 00h12m42s 0
int-PE-3-PE-2 0
192.168.34.0/30 Local Local 00h12m42s 0
int-PE-3-PE-4 0
-------------------------------------------------------------------------------
No. of Routes: 5
Flags: n = Number of times nexthop is repeated
B = BGP backup route available
L = LFA nexthop available
S = Sticky ECMP requested
===============================================================================
Show commands on PE-2
The commands on PE-2 are as follows:
*A:PE-2# 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 64500 36 0 00h16m24s 1/0/1 (Lbl-IPv4)
36 0
192.168.23.2
Def. Instance 64501 36 0 00h16m19s 1/1/1 (Lbl-IPv4)
36 0
-------------------------------------------------------------------------------
The BGP labels are swapped by PE-2 as follows:
*A:PE-2# 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
-------------------------------------------------------------------------------
192.0.2.1 524285 524285 Internal
192.168.23.2 524286 524284 External
-------------------------------------------------------------------------------
Total Labels allocated: 2
===============================================================================
*A:PE-2# show router route-table
===============================================================================
Route Table (Router: Base)
===============================================================================
Dest Prefix[Flags] Type Proto Age Pref
Next Hop[Interface Name] Metric
-------------------------------------------------------------------------------
192.0.2.1/32 Remote ISIS 00h13m43s 15
192.168.12.1 10
192.0.2.2/32 Local Local 00h13m50s 0
system 0
192.0.2.5/32 Remote BGP_LABEL 00h11m01s 170
192.168.23.2 0
192.168.12.0/30 Local Local 00h13m50s 0
int-PE-2-PE-1 0
192.168.23.0/30 Local Local 00h13m50s 0
int-PE-2-PE-3 0
-------------------------------------------------------------------------------
No. of Routes: 5
Flags: n = Number of times nexthop is repeated
B = BGP backup route available
L = LFA nexthop available
S = Sticky ECMP requested
===============================================================================
Show commands on PE-4
The show commands on PE-4 are the following:
*A:PE-4# 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
-------------------------------------------------------------------------------
192.0.2.5
Def. Instance 64502 29 0 00h12m43s 1/0/1 (Lbl-IPv4)
29 0
192.168.34.1
Def. Instance 64501 29 0 00h12m53s 1/1/1 (Lbl-IPv4)
30 0
-------------------------------------------------------------------------------
*A:PE-4# show router bgp routes label-ipv4
===============================================================================
BGP Router ID:192.0.2.4 AS:64502 Local AS:64502
===============================================================================
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 Routes
===============================================================================
Flag Network LocalPref MED
Nexthop (Router) Path-Id IGP Cost
As-Path Label
-------------------------------------------------------------------------------
u*>i 192.0.2.1/32 None None
192.168.34.1 None 0
64501 64500 524287
*i 192.0.2.5/32 100 None
192.0.2.5 None 10
No As-Path 524285
-------------------------------------------------------------------------------
Routes : 2
===============================================================================
*A:PE-4# 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
-------------------------------------------------------------------------------
192.0.2.5 524285 524284 Internal
192.168.34.1 524287 524285 External
-------------------------------------------------------------------------------
Total Labels allocated: 2
===============================================================================
Conclusion
The BGP tunnel-based SDP binding is allowed for VLL and VPLS services, including PBB-VPLS. Using RFC 3107, it is possible to implement inter-AS Model C VLLs.
The example used in this chapter illustrates the configuration of an Inter-AS VLL providing access to CE sites. Troubleshooting commands also have been shown to verify all the procedures.