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IPV6 BGP routes not installed in Routing Table

m-oyegunle
Level 1
Level 1


Hello,

I am peering with various IPV6 peers and i am receiving routes from my peers but I am not installing routes in my routing table.


Below are various outputs (output values are truncated)

1. shows the ipv6 bgp output table, showing a neighbor and amounf of the prefixes received.
2. shows the ipv6 routes received from the neighbor BBBB:BBB:1::a500:BBB:B, (other routes have been removed)
3. shows that the next hops are reachable

I am using an ASR 9001 - S, IOS XR version 5.1.2


RP/0/RSP0/CPU0:#sh bgp ipv6 unicast summary
Mon Feb  1 13:50:59.399 WAT
BGP router identifier XX.XX.XX.XX, local AS number XXXXX
BGP generic scan interval 60 secs
BGP table state: Active
Table ID: 0xe0800000   RD version: 3007
BGP main routing table version 3007
BGP scan interval 60 secs

BGP is operating in STANDALONE mode.


Process       RcvTblVer   bRIB/RIB   LabelVer  ImportVer  SendTblVer  StandbyVer
Speaker            3007          1          0       3007           1           0

Neighbor        Spk    AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down  St/PfxRcd
BBBB:BBB:1::a500:BBB:B
                  0   XXX    3917    3858        0    0    0    1d07h          5

.................................................................

RP/0/RSP0/CPU0:#sh bgp ipv6 unicast neighbors BBBB:BBB:1::a500:BBB:B routes
Mon Feb  1 13:53:23.092 WAT
BGP router identifier XX.XX.XX.XXX, local AS number XXXX
BGP generic scan interval 60 secs
BGP table state: Active
Table ID: 0xe0800000   RD version: 3007
BGP main routing table version 3007
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
*  CCCC:CCC:CCC::/48  BBBB:BBB:1::a500:BBB:B
                                               0             0 XXX i

................................................................


RP/0/RSP0/CPU0:#ping BBBB:BBB:1::a500:BBB:B
Mon Feb  1 13:54:12.683 WAT
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to BBBB:BBB:1::a500:BBB:B, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 123/124/125 ms

13 Replies 13

Philip D'Ath
VIP Alumni
VIP Alumni

What is the output of:

show bgp ipv6 unicast CCCC:CCC:CCC::/48

Could you maybe post the output of:

debug bgp vpnv6 unicast 

and then reset the BGP IPv6 peer.

Hello Philip,

the second suggestion is out of context the original poster is not running 6VPE, it is simply a question of multiple eBGP peerings in IPv6. The path from this neighbor is not the best so it is not installed in the IPv6 routing table.

Hope to help

Giuseppe

I just posted the prefix above as an example.

None of the ipv6 prefixes i am receiving are installed in the routing table, even best

RP/0/RSP0/CPU0:#sh bgp ipv6 unicast
Tue Feb  2 20:32:43.057 WAT
BGP router identifier 44.44.44.444, local AS number 333XX
BGP generic scan interval 60 secs
BGP table state: Active
Table ID: 0xe0800000   RD version: 3531
BGP main routing table version 3531
BGP scan interval 60 secs

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
   Network            Next Hop            Metric LocPrf Weight Path
*  2001::/32          2001:FFF:F::a500:FFFF:1
                                             100             0 2222 1111 0000 i
*                     2001:FFF:F::a500:FFFF:1
                                              30             0 6666 29900 i
*                     2001:FFF:F::FFFF:1
                                              40             0 6666 23232 i
*>                    2001:FFF:F::FFFF:1
                                               0             0 9999 i


output truncated

ALl i get in my table are directly connected routes


RP/0/RSP0/CPU0:INT-IXP-A9K-PR-01#sh route ipv6
Tue Feb  2 20:35:19.856 WAT

Codes: C - connected, S - static, R - RIP, B - BGP, (>) - Diversion path
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - ISIS, L1 - IS-IS le
vel-1, L2 - IS-IS level-2
       ia - IS-IS inter area, su - IS-IS summary null, * - candidate default
       U - per-user static route, o - ODR, L - local, G  - DAGR
       A - access/subscriber, a - Application route, (!) - FRR Backup path

Gateway of last resort is not set

C    2001:FFF:X::/64 is directly connected,
      2d18h, GigabitEthernet0/0/1/0
L    2001:FFF:X::a503:FFFF:1/128 is directly connected,
      2d18h, GigabitEthernet0/0/1/0
C    2001:FFF:X::/64 is directly connected,
      2d14h, TenGigE0/0/2/1
L    2001:FFF:X::FFFF:1/128 is directly connected,
      2d14h, TenGigE0/0/2/1

Output

RP/0/RSP0/CPU0:#sh bgp ipv6 unicast CCCC:C:CCC::/48
Tue Feb 2 20:08:12.390 WAT
BGP routing table entry for CCCC:C:CCC::/48
Versions:
Process bRIB/RIB SendTblVer
Speaker 2304 2304
Last Modified: Jan 31 06:28:09.353 for 2d13h
Paths: (1 available, best #1)
Not advertised to any peer
Path #1: Received by speaker 0
Not advertised to any peer
ASAS
XXXX:XXX:X::XXX:1 from XXXX:XXX:X::XXX:1 (22.22.222.2)
Origin IGP, metric 0, localpref 100, valid, external, best, group-best, import-candidate
Received Path ID 0, Local Path ID 1, version 2304
Community: 55555:ASAS
Origin-AS validity: not-found

Re;

debug bgp vpnv6 unicast 

I am guessing the syntax for the command in ios xr is different, so i ran the debug command below

"debug bgp address-family vpnv6 unicast" this however did not produce any output and i think that is fine cause i am not receiving any vpnv6 routes, so i ran the debug for ipv6 unicast i.e.
debug bgp address-family ipv6 unicast,

Below is the output


RP/0/RSP0/CPU0:Feb 2 20:14:36.458 WAT: bgp[1054]: %ROUTING-BGP-5-ADJCHANGE_DETAIL : neighbor XXXX:XXX:X::XXX:1 Up (VRF: default; AFI/SAFI: 2/1) (AS: ASAS)

RP/0/RSP0/CPU0:Feb 2 20:14:37.608 WAT: bgp[1054]: [default-rtr] (ip6u): ===bgp_add_path===: net=3333:0:333::/48, nver=3527, nfl=0x04000001: newpath=0x51097a10(XXXX:XXX:X::XXX:1/128,XXXX:XXX:X::XXX:1,0,0x4000000000020001): link=1, pcount=1

RP/0/RSP0/CPU0:Feb 2 20:14:37.608 WAT: bgp[1054]: [default-rtr] (ip6u): Not an import multipath -> import multipath for 3333:0:333::/48 from XXXX:XXX:X::XXX:1 (path: ASAS)

RP/0/RSP0/CPU0:Feb 2 20:14:37.608 WAT: bgp[1054]: [default-rtr] (ip6u): ===bgp_bestpath===: net=2620:0:870::/48, nver=3527, nfl=0x04000001: lastpath=0x51097a10(XXXX:XXX:X::XXX:1/128,XXXX:XXX:X::XXX:1,0,0x4000000000020001): PELEM=0x0(lpathid=0, ver=0, fl=0x00000000, path=0x0)

RP/0/RSP0/CPU0:Feb 2 20:14:37.608 WAT: bgp[1054]: [default-rtr] (ip6u): ===bgp_calculate_bestpath===: net=3333:0:333::/48, nver=3527, nfl=0x04040001, pelemver=3527: oldbest=0x0(NULL,::,0), newbest=0x51097a10(XXXX:XXX:X::XXX:1/128,2001:XXXX:XXX:X::XXX:10), bumpv=1

RP/0/RSP0/CPU0:Feb 2 20:14:37.608 WAT: bgp[1054]: [default-rtr] (ip6u): ===bgp_change_bestpath===: net=3333:0:333::/48, nver=3527, nfl=0x04040001: oldbest=0x0: PELEM=0x510b8e04(lpathid=1, ver=3527, fl=0x00001101, path=0x51097a10)

RP/0/RSP0/CPU0:Feb 2 20:14:37.608 WAT: bgp[1054]: [default-rtr] (ip6u): ===bnet_chgflags_update===: net=3333:0:333::/48, nver=3527, nfl=0x04040001: oldtblattr=0x0, oldnh=0x0: PELEM=0x510b8e04(lpathid=1, ver=3527, fl=0x00001101, path=0x51097a10)

RP/0/RSP0/CPU0:Feb 2 20:14:37.608 WAT: bgp[1054]: [default-rtr] (ip6u): ===bgp_bestpath===: COMPLETE: net=3333:0:333::/48, nver=3527, nfl=0x04044001: pselect=0, bumpv=1(1:1,0,0,0)

Could you post the output of:

show ipv6 route CCCC:C:CCC::/48

RP/0/RSP0/CPU0:#sh route ipv6 CCCC:C:CCC::/48
Tue Feb  2 20:40:16.039 WAT

% Network not in table

Hello,

Had to contact Cisco TAC, turned out to be a software bug.

"CSCuq79148 - BGP label thread is stuck in CDM init:"

This bug is fixed starting with IOS XR 5.1.3 so an IOS upgrade is required.

The workaround is to reset the BGP process which i did and i can install IPV6 routes now.

Thank you all

Hello M-oyegunle,

you have been kind to provide feedback on this issue. Now this thread has an happy end.

So it was a SW bug.

Best Regards

Giuseppe

Hello, m-o

there is a single BGP advertisement for the prefix and it is considered best. it should be installed.

is the prefix learned in some other way a static route?

RP/0/RSP0/CPU0:#sh bgp ipv6 unicast CCCC:C:CCC::/48
Tue Feb 2 20:08:12.390 WAT
BGP routing table entry for CCCC:C:CCC::/48
Versions:
Process bRIB/RIB SendTblVer
Speaker 2304 2304
Last Modified: Jan 31 06:28:09.353 for 2d13h
Paths: (1 available, best #1)
Not advertised to any peer
Path #1: Received by speaker 0
Not advertised to any peer
ASAS
XXXX:XXX:X::XXX:1 from XXXX:XXX:X::XXX:1 (22.22.222.2)
Origin IGP, metric 0, localpref 100, valid, external, <<<<best<<<, group-best, import-candidate
Received Path ID 0, Local Path ID 1, version 2304
Community: 55555:ASAS
Origin-AS validity: not-found

Do you know that you need a policy written in RPL to accept the prefix from an eBGP peer in IOS XR?

Have you applied a policy like 

route-policy  PASS-ALL

pass

end-policy

see

http://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k_r5-3/routing/configuration/guide/b_routing_cg53xasr9k/b_routing_cg53xasr9k_chapter_010.html#con_1197962

Hope to help

Giuseppe

No the prefix is not learned via any other way.

and yes i have route policies applied in both inbound and outbound directions

Philip D'Ath
VIP Alumni
VIP Alumni

You definately have ipv6 unicast routing enabled?

ipv6 unicast-routing

m-oyegunle
Level 1
Level 1

ipv6 unicast-routing is enabled by default in IOS_XR yeah?

Hello, m-oyegunle yes ipv6 unicast routing is enabled by default in IOS XR.

I don't see the '>' near the CCCC:CCCC:CCC::/48 prefix, you may be learning the prefix in some other way?

the missing '>' means the BGP is not considered best by BGP.

Your router might have installed the prefix from another eBGP session.

Hope to help

Giuseppe

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