×

Warning message

  • Cisco Support Forums is in Read Only mode while the site is being migrated.
  • Cisco Support Forums is in Read Only mode while the site is being migrated.

VRF and CEF adj table

Unanswered Question
Apr 26th, 2012
User Badges:

Hello!


I've faced with CEF adj table overflow on SUP720-3BXL when tried to import BGP Full View into VRF on PE.


The scheme is following: border router R1 (6500 SUP720-3BXL) is MPLS PE. BGP session with uplinks are configured in address-family ipv4 vrf Uplink.

I use "Per VRF label" feature for VRF Uplink due to TCAM limitations.


There is another PE router R2 (6500 SUP720-3BXL) in the network with VRF Uplink.

R2 has a problem with CEF adj table overflow because it creates adj entry for each prefix from BGP Full View instead of common entry for all traffic to R01. The content of these adj entries is identical.


Here is some output from R1 and R2:

R1#sh mls cef vrf Uplink 12.43.140.0 24 detail

Codes: M - mask entry, V - value entry, A - adjacency index, P - priority bit
D - full don't switch, m - load balancing modnumber, B - BGP Bucket sel
V0 - Vlan 0,C0 - don't comp bit 0,V1 - Vlan 1,C1 - don't comp bit 1
RVTEN - RPF Vlan table enable, RVTSEL - RPF Vlan table select
Format: IPV4_DA - (8 | xtag vpn pi cr recirc tos prefix)
Format: IPV4_SA - (9 | xtag vpn pi cr recirc prefix)
M(5446   ): E | 1 FFF  0 0 0 0   255.255.255.0
V(5446   ): 8 | 1 1    0 0 0 0   12.43.140.0        (A:360615 ,P:1,D:0,m:0 ,B:0 )


R1#sh mls cef vrf Uplink 12.43.146.0 24 detail


Codes: M - mask entry, V - value entry, A - adjacency index, P - priority bit
D - full don't switch, m - load balancing modnumber, B - BGP Bucket sel
V0 - Vlan 0,C0 - don't comp bit 0,V1 - Vlan 1,C1 - don't comp bit 1
RVTEN - RPF Vlan table enable, RVTSEL - RPF Vlan table select
Format: IPV4_DA - (8 | xtag vpn pi cr recirc tos prefix)
Format: IPV4_SA - (9 | xtag vpn pi cr recirc prefix)
M(5447   ): E | 1 FFF  0 0 0 0   255.255.255.0
V(5447   ): 8 | 1 1    0 0 0 0   12.43.146.0        (A:360615 ,P:1,D:0,m:0 ,B:0 )


R2#sh mls cef vrf Uplink 12.43.140.0 24 detail


Codes: M - mask entry, V - value entry, A - adjacency index, P - priority bit
D - full don't switch, m - load balancing modnumber, B - BGP Bucket sel
V0 - Vlan 0,C0 - don't comp bit 0,V1 - Vlan 1,C1 - don't comp bit 1
RVTEN - RPF Vlan table enable, RVTSEL - RPF Vlan table select
Format: IPV4_DA - (8 | xtag vpn pi cr recirc tos prefix)
Format: IPV4_SA - (9 | xtag vpn pi cr recirc prefix)
M(4728   ): E | 1 FFF  0 0 0 0   255.255.255.0
V(4728   ): 8 | 1 1    0 0 0 0   12.43.140.0        (A:294998 ,P:1,D:0,m:0 ,B:0 )


R2#sh mls cef vrf Uplink 12.43.146.0 24 detail

Codes: M - mask entry, V - value entry, A - adjacency index, P - priority bit
D - full don't switch, m - load balancing modnumber, B - BGP Bucket sel
V0 - Vlan 0,C0 - don't comp bit 0,V1 - Vlan 1,C1 - don't comp bit 1
RVTEN - RPF Vlan table enable, RVTSEL - RPF Vlan table select
Format: IPV4_DA - (8 | xtag vpn pi cr recirc tos prefix)
Format: IPV4_SA - (9 | xtag vpn pi cr recirc prefix)
M(4729   ): E | 1 FFF  0 0 0 0   255.255.255.0
V(4729   ): 8 | 1 1    0 0 0 0   12.43.146.0        (A:311382 ,P:1,D:0,m:0 ,B:0 )


R2#sh mls cef adjacency entry 294998 detail


Index: 294998  smac: 0002.7eb5.7000, dmac: 00d0.01f9.c000
mtu: 9018, vlan: 1020, dindex: 0x0, l3rw_vld: 1
format: MPLS, flags: 0x8418
label0: 0, exp: 0, ovr: 0
label1: 16, exp: 0, ovr: 0
label2: 453, exp: 0, ovr: 0
op: PUSH_LABEL2_LABEL1
packets: 0, bytes: 0


R2#sh mls cef adjacency entry 311382 detail


Index: 311382  smac: 0002.7eb5.7000, dmac: 00d0.01f9.c000
mtu: 9018, vlan: 1020, dindex: 0x0, l3rw_vld: 1
format: MPLS, flags: 0x8418
label0: 0, exp: 0, ovr: 0
label1: 16, exp: 0, ovr: 0
label2: 453, exp: 0, ovr: 0
op: PUSH_LABEL2_LABEL1
packets: 0, bytes: 0


It seems to me that 6500 need 1 adj entry for 1 FEC and it can't summarize all traffic with defined label to 1 FEC. Am i right?

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
Vladimir Troitskiy Thu, 05/03/2012 - 05:41
User Badges:

Actually my assumption about FEC was wrong.


Briefly the question is why CEF creates per prefix adjacency entry instead of per nexthop one in this VRF environment?

yashfaqu Fri, 05/04/2012 - 01:53
User Badges:

Can you share the "ip route" and "ip cef detail" for both prefixes from both boxes?

Vladimir Troitskiy Fri, 05/04/2012 - 03:08
User Badges:

Hi, Yasir.


Thank for your reply!


R1 is a border router - routes are point to Uplink ISP:


R1#sh ip route vrf Uplink 12.43.140.0
Routing entry for 12.43.140.0/24
  Known via "bgp 12668", distance 20, metric 25
  Tag 31133, type external
  Last update from 85.26.237.46 20:04:33 ago
  Routing Descriptor Blocks:
  * 85.26.237.46, from 85.26.237.46, 20:04:33 ago
      Route metric is 25, traffic share count is 1
      AS Hops 4
      Route tag 31133
      MPLS label: none


R1#sh ip route vrf Uplink 12.43.146.0
Routing entry for 12.43.146.0/24
  Known via "bgp 12668", distance 20, metric 25
  Tag 31133, type external
  Last update from 85.26.237.46 20:04:43 ago
  Routing Descriptor Blocks:
  * 85.26.237.46, from 85.26.237.46, 20:04:43 ago
      Route metric is 25, traffic share count is 1
      AS Hops 4
      Route tag 31133
      MPLS label: none


R1#sh ip cef vrf Uplink 12.43.140.0/24 detail

12.43.140.0/24, epoch 1, flags rib only nolabel, rib defined all labels
NetFlow: Origin AS 16711, Peer AS 0, Mask Bits 24
recursive via 85.26.237.46
attached to TenGigabitEthernet2/4.800


R1#sh ip cef vrf Uplink 12.43.146.0/24 detail

12.43.146.0/24, epoch 1, flags rib only nolabel, rib defined all labels
NetFlow: Origin AS 16711, Peer AS 0, Mask Bits 24
recursive via 85.26.237.46
attached to TenGigabitEthernet2/4.800



R2 is a PE Router - routes are point to border router R1 (212.49.96.9):


R2#sh ip route vrf Uplink 12.43.140.0
Routing entry for 12.43.140.0/24
  Known via "bgp 12668", distance 200, metric 25
  Tag 31133, type internal
  Last update from 212.49.96.9 20:05:29 ago
  Routing Descriptor Blocks:
  * 212.49.96.9 (Default-IP-Routing-Table), from 212.49.96.9, 20:05:29 ago
      Route metric is 25, traffic share count is 1
      AS Hops 4
      Route tag 31133
      MPLS label: 16
      MPLS Flags: MPLS Required


R2#sh ip route vrf Uplink 12.43.146.0
Routing entry for 12.43.146.0/24
  Known via "bgp 12668", distance 200, metric 25
  Tag 31133, type internal
  Last update from 212.49.96.9 20:05:37 ago
  Routing Descriptor Blocks:
  * 212.49.96.9 (Default-IP-Routing-Table), from 212.49.96.9, 20:05:37 ago
      Route metric is 25, traffic share count is 1
      AS Hops 4
      Route tag 31133
      MPLS label: 16
      MPLS Flags: MPLS Required


R2#sh ip cef vrf Uplink 12.43.140.0/24 detail

12.43.140.0/24, epoch 1, flags rib defined all labels
recursive via 212.49.96.9 label 16
nexthop 92.242.31.81 GigabitEthernet5/1 label 453


R2#sh ip cef vrf Uplink 12.43.146.0/24 detail

12.43.146.0/24, epoch 1, flags rib defined all labels
recursive via 212.49.96.9 label 16
nexthop 92.242.31.81 GigabitEthernet5/1 label 453

Actions

This Discussion