Vpnv4 Label mapping Cisco XR

[Sunil_06]

Hi Team, 

i have topology of three routers (R1----->R2------>R3) 

R1 and R3 are acting as PE device while R2 is RR. 

Please confirm whether below behavior is normal or not. 

R1 is receiving prefix 1.1.1.128/25 from R3 with RD of 1234:11 and VPN Label 24083. 

but when i'm checking label at R3 router , it is showing inactive and its mapped to another prefix in different VRF (1234:12)

RP/0/RSP0/CPU0:R1# show bgp vrf A 1.1.1.132
Tue Oct 4 18:06:41.643 IST
BGP routing table entry for 1.1.1.128/25, Route Distinguisher: 2.2.2.21:12
Versions:
Process bRIB/RIB SendTblVer
Speaker 249292149 249292149
Last Modified: Sep 18 01:23:23.920 for 2w2d
Paths: (1 available, best #1)
Not advertised to any peer
Path #1: Received by speaker 0
Not advertised to any peer
2.2.2.48 (metric 11) from 2.2.2.36 (2.2.2.48)
Received Label 24083
Origin incomplete, localpref 100, valid, internal, best, group-best, import-candidate, imported
Received Path ID 0, Local Path ID 1, version 249292149
Extended community: SoO:123:180 RT:1234:11
Originator: 2.2.2.48, Cluster list: 0.0.0.51
Source AFI: VPNv4 Unicast, Source VRF: default, Source Route Distinguisher: 1234:11
RP/0/RSP0/CPU0:R1#

RP/0/RSP0/CPU0:R3#show bgp label 24083
Tue Oct 4 18:17:44.633 IST
BGP Label Entry: 24083 (inactive)
Last Updated : Oct 03 20:28:29.960 (21:49:14 ago)
Label Type : IPv4 VRF Prefix
VRF/RD : 1234:12
Label Context: 5.5.5.5/32
Refcount : 0

RP/0/RSP0/CPU0:R3#

RP/0/RSP0/CPU0:R3#show cef vrf A 1.1.1.132
Tue Oct 4 17:39:03.244 IST
1.1.1.128/25, version 143513060, internal 0x1000001 0x0 (ptr 0x73d5c9a4) [1], 0x0 (0x0), 0x200 (0x7369bfe8)
Updated Sep 29 04:05:31.247
Prefix Len 25, traffic index 0, precedence n/a, priority 3
via 5.5.5.7, 3 dependencies, recursive, bgp-ext [flags 0x6020]
path-idx 0 NHID 0x0 [0x734d3114 0x0]
next hop 5.5.5.7 via 5.5.5.7/32
local label 24192
next hop 5.5.5.7/32 BE40.1021 labels imposed {None}
RP/0/RSP0/CPU0:R3#

BR://

Sunil

[MHM Cisco World]

there are two Label in VPNv4
upper is for the BGP peer IP  24083 (R1-R2-R3 use upper label to forward traffic from R1 to R3)
lower is for VPN  24192

[Harold Ritter]

Hi @Sunil_06 ,

The "show bgp label" command will display the BGP received labels.

You need to do a "show mpls for labels 24083" on R3 to check that the label is properly installed in the local LFIB.

Regards,

[Sunil_06]

Hi Harold ,

Thanks for your responce  

whats this lable 24192, that Cef table is showing ?

RP/0/RSP0/CPU0:R3#show cef vrf A 1.1.1.132
Tue Oct 4 17:39:03.244 IST
1.1.1.128/25, version 143513060, internal 0x1000001 0x0 (ptr 0x73d5c9a4) [1], 0x0 (0x0), 0x200 (0x7369bfe8)
Updated Sep 29 04:05:31.247
Prefix Len 25, traffic index 0, precedence n/a, priority 3
via 5.5.5.7, 3 dependencies, recursive, bgp-ext [flags 0x6020]
path-idx 0 NHID 0x0 [0x734d3114 0x0]
next hop 5.5.5.7 via 5.5.5.7/32
local label 24192
next hop 5.5.5.7/32 BE40.1021 labels imposed {None}
RP/0/RSP0/CPU0:R3#

Sunil Kumar

[Harold Ritter]

Hi @Sunil_06 ,

The local label is the label that is locally allocated for the VRF prefix and it should be the label advertised via BGP vpnv4. Interestingly enough, it does match in your case. I would recommend running the command "clear bgp vpnv4 uni * soft in" on R1 and check to see if it solves the discrepancy that is seen between the label on R1 and R3 for 1.1.1.128/25.

Regards,

[MHM Cisco World]

can you show mpls forwarding table 

[Sunil_06]

HI , 

Please find below output. 

RP/0/RSP0/CPU0:R1#show cef vrf A 1.1.1.132
Thu Oct 6 09:51:09.538 IST
1.1.1.128/25, version 113990, internal 0x5000001 0x0 (ptr 0x73dc2870) [1], 0x0 (0x0), 0x208 (0x7384f668)
Updated Sep 18 01:23:24.426
Prefix Len 25, traffic index 0, precedence n/a, priority 3
via 3.3.3.3/32, 7 dependencies, recursive [flags 0x6000]
path-idx 0 NHID 0x0 [0x72982f88 0x0]
recursion-via-/32
next hop VRF - 'default', table - 0xe0000000
next hop 3.3.3.3 via 24413/0/21
next hop 1.3.1.3/32 BE5.10 labels imposed {ImplNull 24083}           <<<<implNull because i have direct link between R1 & R3
RP/0/RSP0/CPU0:R1#

RP/0/RSP0/CPU0:R3#show mpls forwarding labels 24083
Thu Oct 6 09:52:21.970 IST
RP/0/RSP0/CPU0:R3#

RP/0/RSP0/CPU0:R3#show mpls forwarding labels 24192
Thu Oct 6 09:52:48.528 IST
Local Outgoing Prefix Outgoing Next Hop Bytes    Label Label or ID Interface Switched
------ ----------- ------------------ ------------ --------------- ------------
24192 Unlabelled 1.1.1.128/25[V] \          BE40.1021 5.5.5.7 0
RP/0/RSP0/CPU0:R3#

RP/0/RSP0/CPU0:R3#show version
Thu Oct 6 10:01:32.754 IST

Cisco IOS XR Software, Version 5.2.4[Default]
Copyright (c) 2015 by Cisco Systems, Inc.

ROM: System Bootstrap, Version 0.71(c) 1994-2012 by Cisco Systems, Inc.

R3 uptime is 6 years, 31 weeks, 3 days, 15 hours, 50 minutes
System image file is "disk0:asr9k-os-mbi-5.2.4/0x100305/mbiasr9k-rsp3.vm"

cisco ASR9K Series (Intel 686 F6M14S4) processor with 12582912K bytes of memory.
Intel 686 F6M14S4 processor at 2128MHz, Revision 2.174
ASR 9006 DC Chassis with PEM Version 2

[MHM Cisco World]

 show mpls forwarding <<- I need full table 
in each R1 R2 & R3