Hey folks,
Background
I am running a home lab and practicing on InterAS Option C with IOSXR, the OSes here are IOSXRv and IOSXR9kv, naming is used accordingly in the post.
Topology
Description
We are in AS 400. iosxrv-2 is the ASBR and BGP ipv4 labelled-unicast RR (it uses next-hop-self for the ipv4 labelled unicast af). iosxr-9k-2 is one of the internal peers in AS 400 peers, it receives remote loopbacks addresses from iosxrv-2 and runs a eBGP VPNv4 peering with a remote PE 6.6.6.6 in AS 100 (Inter AS Option C).
All goes well before establishing the eBGP VPNv4 peering, iosxr-9k-2 can trace to the remote PE fully labelled (traceroute 6.6.6.6 so 102.102.102.102)
RP/0/RP0/CPU0:iosxr-9k-2#trace 6.6.6.6 so 102.102.102.102 Sun Jan 10 15:35:05.516 UTC Type escape sequence to abort. Tracing the route to 6.6.6.6 1 189.148.139.1 [MPLS: Label 16008 Exp 0] 5 msec 3 msec 3 msec < -- label 2 152.218.199.2 [MPLS: Label 16003 Exp 0] 3 msec 3 msec 3 msec 3 177.191.130.1 [MPLS: Label 16000 Exp 0] 3 msec 3 msec 3 msec 4 139.208.128.1 3 msec * 3 msec
The problem starts when eBGP VPNv4 peering is configured, in fact probably due to the following:
the local PE stops binding a label for the remote PE address which makes the traffic to the remote PE unlabeled in the first hop.
This represents a problem given that L3 VPN packets need underlying transport label and that just isn't there.
RP/0/RP0/CPU0:iosxr-9k-2#trace 6.6.6.6 so 102.102.102.102 Sun Jan 10 15:35:55.780 UTC Type escape sequence to abort. Tracing the route to 6.6.6.6 1 189.148.139.1 3 msec 1 msec 2 msec < -- no label 2 152.218.199.2 [MPLS: Label 16003 Exp 0] 4 msec 3 msec 3 msec 3 177.191.130.1 [MPLS: Label 16000 Exp 0] 3 msec 3 msec 3 msec 4 139.208.128.1 3 msec * 4 msec
Configurations
iosxr-9k-2
router bgp 400 address-family ipv4 unicast allocate-label all ! address-family vpnv4 unicast ! address-family ipv6 unicast ! address-family vpnv6 unicast ! neighbor 2.2.2.2 < -- iosxrv-2 (ASBR RR) remote-as 400 update-source Loopback0 address-family ipv4 labeled-unicast ! neighbor 6.6.6.6 < -- remote PE remote-as 100 ebgp-multihop 255 update-source Loopback0 address-family vpnv4 unicast route-policy PASS in route-policy PASS out ! address-family vpnv6 unicast route-policy PASS in route-policy PASS out
iosxrv2
router bgp 400 address-family ipv4 unicast network 102.102.102.102/32 < -- iosxr-9k-2 (local PE) loopback address allocate-label all ! address-family vpnv4 unicast ! address-family vpnv6 unicast ! neighbor-group ibgp remote-as 400 update-source Loopback0 address-family ipv4 labeled-unicast route-reflector-client next-hop-self ! neighbor 152.218.199.2 < -- remote AS remote-as 100 address-family ipv4 labeled-unicast route-policy PASS in route-policy PASS out ! ! neighbor 102.102.102.102 < -- iosxr-9k-2 (local PE) use neighbor-group ibgp
Outputs
RP/0/RP0/CPU0:iosxr-9k-2#sh mpls forwarding prefix 6.6.6.6/32 Sun Jan 10 15:17:03.736 UTC Local Outgoing Prefix Outgoing Next Hop Bytes Label Label or ID Interface Switched ------ ----------- ------------------ ------------ --------------- ------------ 24003 Pop 6.6.6.6/32 Gi0/0/0/0.522 189.148.139.1 576
Output after removing vpnv4 neighbor
RP/0/RP0/CPU0:iosxr-9k-2#conf t Sun Jan 10 15:17:15.729 UTC no RP/0/RP0/CPU0:iosxr-9k-2(config)#router bgp 400 RP/0/RP0/CPU0:iosxr-9k-2(config-bgp)#no nei 6.6.6.6 RP/0/RP0/CPU0:iosxr-9k-2(config-bgp)#commit RP/0/RP0/CPU0:iosxr-9k-2(config-bgp)#end RP/0/RP0/CPU0:iosxr-9k-2#sh mpls forwarding prefix 6.6.6.6/32 Sun Jan 10 15:17:27.356 UTC Local Outgoing Prefix Outgoing Next Hop Bytes Label Label or ID Interface Switched ------ ----------- ------------------ ------------ --------------- ------------ 24003 16008 6.6.6.6/32 2.2.2.2 0 RP/0/RP0/CPU0:iosxr-9k-2#
I know between directly connected eBGP vpnv4/ipv4-labelled peers a static route to the neighbor would generate a /32 entry in rib and that would do the trick.
Question
How about in this case? The eBGP VPNv4 peering is remote and I am not sure how to ensure the traffic would travel labelled all the way.
It is the same thing on the other AS. Also the behavior is flaky, reconfiguring multiple times makes the next hop stay as 2.2.2.2 and the label stick. Not sure how to fix this, please advise.
Thanks, L.
Accepted Solutions
