02-01-2022 04:09 PM
Thank you for your answer.
I used the NCS55A2-MOD-SE-S and the ASR9901 to create a verification environment for the SRv6/MPLS L3 Service Interworking Gateway.
NCS55-1 is SR-MPLS and NCS55-2 is Gateway and ASR9901 is SRv6.
Version is 7.5.1.
-----------------------------------------------------
[vrf RED] - (NCS55-1) - (NCS55-2) - (ASR9901) - [vrf RED]
SR-MPLS Gateway SRv6
-----------------------------------------------------
I have created a configuration from the manual, but I cannot communicate between L3VPN services.
It looks like the Gateway is getting the prefix information for both routers, but not sending it to the other router.
[Gateway: show bgp vpnv4 unicast]
Route Distinguisher: 1:1 (default for vrf RED) *>i101.1.1.0/24 1.1.1.1 100 0 11 i *>i101.2.2.0/24 b:0:0:2::1 100 0 21 i Processed 2 prefixes, 2 paths
[NCS55-1:show bgp vpnv4 unicast summary]
Neighbor Spk AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down St/PfxRcd 1.1.1.3 0 65000 59 58 7 0 0 00:54:55 0
[ASR9901:show bgp vpnv4 unicast summary]
Neighbor Spk AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down St/PfxRcd b:0:0:3::1 0 65000 56 56 7 0 0 00:52:06 0
However, it looks like the prefix information is being sent from the Gateway to both routers.
[Gateway:show bgp vpnv4 unicast advertised]
Route Distinguisher: 1:1 101.1.1.0/24 is advertised to b:0:0:2::1 Path info: neighbor: 1.1.1.1 neighbor router id: 1.1.1.1 (Received from a RR-client) valid internal best import-candidate imported reoriginated with stitching-rt Received Path ID 0, Local Path ID 1, version 5 Attributes after inbound policy was applied: next hop: 1.1.1.1 ORG AS LOCAL EXTCOMM origin: IGP neighbor as: 11 local pref: 100 aspath: 11 extended community: RT:1:1 Attributes after outbound policy was applied: next hop: 1.1.1.1 ORG AS LOCAL EXTCOMM origin: IGP neighbor as: 11 local pref: 100 aspath: 11 extended community: RT:1:1 originator: 1.1.1.1 cluster list: 1.1.1.3 Route Distinguisher: 1:1 101.2.2.0/24 is advertised to 1.1.1.1 Path info: neighbor: b:0:0:2::1 neighbor router id: 1.1.1.2 (Received from a RR-client) valid internal best import-candidate imported reoriginated Received Path ID 0, Local Path ID 1, version 8 Attributes after inbound policy was applied: next hop: b:0:0:2::1 ORG AS LOCAL EXTCOMM PSID-L3-SID origin: IGP neighbor as: 21 local pref: 100 aspath: 21 extended community: RT:10:1 Attributes after outbound policy was applied: next hop: b:0:0:2::1 ORG AS LOCAL EXTCOMM PSID-L3-SID origin: IGP neighbor as: 21 local pref: 100 aspath: 21 extended community: RT:10:1 originator: 1.1.1.2 cluster list: 1.1.1.3
Can you figure out what is causing it to not work?
Finally, the configuration of the Gateway is shown below.
[Gateway's configuration.]
vrf RED address-family ipv4 unicast import route-target 1:1 10:1 stitching ! export route-target 1:1 10:1 stitching ! router isis 1 is-type level-2-only net 13.1113.1113.1113.00 address-family ipv4 unicast metric-style wide router-id Loopback0 segment-routing mpls ! address-family ipv6 unicast metric-style wide router-id Loopback0 segment-routing srv6 locator Loc1 ! ! ! interface Loopback0 address-family ipv4 unicast prefix-sid index 3 ! address-family ipv6 unicast ! ! interface GigabitEthernet0/0/0/0 circuit-type level-2-only point-to-point address-family ipv4 unicast ! ! interface GigabitEthernet0/0/0/1 circuit-type level-2-only point-to-point address-family ipv6 unicast ! router bgp 65000 bgp router-id 1.1.1.3 segment-routing srv6 locator Loc1 ! address-family vpnv4 unicast ! neighbor 1.1.1.1 remote-as 65000 update-source Loopback0 address-family vpnv4 unicast import reoriginate stitching-rt route-reflector-client advertise vpnv4 unicast re-originated ! ! neighbor b:0:0:2::1 remote-as 65000 update-source Loopback0 address-family vpnv4 unicast import stitching-rt reoriginate route-reflector-client encapsulation-type srv6 advertise vpnv4 unicast re-originated stitching-rt ! ! vrf RED rd 1:1 address-family ipv4 unicast mpls alloc enable label mode per-vrf segment-routing srv6 alloc mode per-vrf ! segment-routing srv6 encapsulation source-address b:0:0:3::1 ! locators locator Loc1 prefix b:0:0:3::/64 !
02-01-2022 05:16 PM
follow
02-02-2022 10:03 AM
Hi @Soushi Takata ,
The gateway should be connected to two different ISIS domains. SRv6 and SR-MPLS. Please refer to the following document for more information.
Regards,
02-02-2022 09:48 PM
Hi Harold,
Thank you for your reply.
I have changed the ISIS on the Gateway Router to Multidomain.
router isis 1 is-type level-2-only net 13.1113.1113.1113.00 address-family ipv4 unicast metric-style wide router-id Loopback0 segment-routing mpls ! interface Loopback0 address-family ipv4 unicast prefix-sid index 3 ! ! interface GigabitEthernet0/0/0/0 circuit-type level-2-only point-to-point address-family ipv4 unicast ! ! ! router isis 2 is-type level-2-only net 13.1113.1113.1113.00 address-family ipv6 unicast metric-style wide router-id Loopback0 segment-routing srv6 locator Loc1 ! ! ! interface Loopback0 address-family ipv6 unicast ! ! interface GigabitEthernet0/0/0/1 circuit-type level-2-only point-to-point address-family ipv6 unicast !
But the situation did not change.
On the other hand, when I tried "debug bgp all" command on NCS55-1 and ASR9901, I got the following message.
[NCS55-1]
bgp[1084]: [default-rtr] (vpn4u): Received UPDATE from 1.1.1.3 with attributes: bgp[1084]: [default-rtr] (vpn4u): nexthop 1.1.1.3/32, origin i, localpref 100, originator 1.1.1.2, clusterlist 3.1.1.1, path 21, extended community RT:10:1 bgp[1084]: [default-rtr] (vpn4u): Received prefix 2ASN:1:1:101.2.2.0/24 (path ID: none) with MPLS label 24002 from neighbor 1.1.1.3 bgp[1084]: [default-rtr] (vpn4u): Prefix 2ASN:1:1:101.2.2.0/24 (path ID: none) received from 1.1.1.3 DENIED RT extended community is not imported locally bgp[1084]: [default-rtr]: Received UPDATE from 1.1.1.3 (length incl. header = 104)
[ASR9901]
bgp[1087]: [default-rtr] (vpn4u): Received UPDATE from b:0:0:3::1 with attributes: bgp[1087]: [default-rtr] (vpn4u): nexthop b:0:0:3::1/128, origin i, localpref 100, originator 1.1.1.1, clusterlist 3.1.1.1, path 11, extended community RT:1:1 bgp[1087]: [default-rtr] (vpn4u): Received prefix 2ASN:1:1:101.1.1.0/24 (path ID: none) with MPLS label 1024 from neighbor b:0:0:3::1 bgp[1087]: [default-rtr] (vpn4u): Prefix 2ASN:1:1:101.1.1.0/24 (path ID: none) received from b:0:0:3::1 DENIED RT extended community is not imported locally
Looking at these, it looks like the RT is not being rewritten at the Gateway.
I'm having trouble because the vrf config and bgp config that seem to be relevant here don't seem to be wrong.
Best Regards,
Soushi
03-06-2022 05:04 PM
Thank you for your answer.
Perhaps this problem has been resolved.
If the RD of the gateway router is different from the other routers(SR-MPLS's PE router and SRv6's PE router), the PE routers can receive the prefix information correctly.
Here is the vpnv4 information for each routers.
[SR-MPLS's PE router]
RP/0/RP0/CPU0:RouterA#show bgp vpnv4 unicast <snip> Network Next Hop Metric LocPrf Weight Path Route Distinguisher: 1.1.1.1:0 (default for vrf RED) *> 101.1.1.0/24 21.1.111.11 0 11 i *>i101.2.2.0/24 1.1.1.3 100 0 21 i Route Distinguisher: 1.1.1.3:0 *>i101.2.2.0/24 1.1.1.3 100 0 21 i
[SRv6's PE router]
RP/0/RSP0/CPU0:RouterB#show bgp vpnv4 unicast <snip> Network Next Hop Metric LocPrf Weight Path Route Distinguisher: 1.1.1.2:0 (default for vrf RED) *>i101.1.1.0/24 b:0:0:3::1 100 0 11 i *> 101.2.2.0/24 21.2.121.12 0 21 i Route Distinguisher: 1.1.1.3:0 *>i101.1.1.0/24 b:0:0:3::1 100 0 11 i
[Gateway router]
RP/0/RP0/CPU0:RouterC#show bgp vpnv4 unicast <snip> Network Next Hop Metric LocPrf Weight Path Route Distinguisher: 1.1.1.1:0 *>i101.1.1.0/24 1.1.1.1 100 0 11 i Route Distinguisher: 1.1.1.2:0 *>i101.2.2.0/24 b:0:0:2::1 100 0 21 i Route Distinguisher: 1.1.1.3:0 (default for vrf RED) *>i101.1.1.0/24 1.1.1.1 100 0 11 i *>i101.2.2.0/24 b:0:0:2::1 100 0 21 i
Although I do not fully understand the logic, I believe this to be correct since interwork communication is possible.
Best Regards,
Soushi
03-06-2022 05:25 PM
Hi @Soushi Takata ,
Glad that it is now working for you. Using a separate RD is best practice in general and that is what I have been successfully been testing in my interworking lab.
Regards,
03-06-2022 06:00 PM
Hi Harold,
Thank you for your reply.
I too believe that the best solution is to have different RDs.
However, there are examples where the same user uses the same RD at each location.
So I don't understand the logic that RD must be a different value, but I will assume that it is a Cisco Router specification.
Best Regards,
Soushi
03-06-2022 06:42 PM
> So I don't understand the logic that RD must be a different value, but I will assume that it is a Cisco Router specification.
Thanks for your comment. I certainly think that this restriction should be documented. I will follow up with the appropriate team.
Regards,
12-07-2023 12:09 PM - edited 12-07-2023 12:16 PM
Thank you very much for this information, i have used same RD too initially and when i configured gateway (NCS55A1) with unique RD everything started working. Before RD fix, control plane was broken (no re-origination in any way). Just for reference, i'm making usage of same ISIS L2 domain but splitted only using BGP vpnv4 to try a migration scenario.
Best regards!
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide