Sharing Equivalence Class entry across multiple VRF

This enables the sharing of the same Forwarding Equivalence Class (FEC) entry across multiple VRF’s and achieves higher scale in VPN deployments by making optimal use of hardware resources. The VPN path routes are imported to multiple VRF for MPLS VPN address family in BGP, individual FEC entry in the hardware table is used for each VRF.

The following configuration in router BGP mode at BGP instance level allows sharing FEC, when the VPN path is imported to multiple VRFs.

bgp fec skip in-place update

The following configures disable FEC and restores default configuration.

[no| default] bgp fec skip in-place update

Note: Changing the configuration in a production system may increase FEC usage.

The following example displays BGP VPN-IPv4 routes for prefix 20.0.1.0/24, which is imported to four VRFs.

switch#show bgp vpn-ipv4 20.0.1.0/24 detail
BGP routing table information for VRF default
Router identifier 0.0.0.1, local AS number 300
BGP routing table entry for IPv4 prefix 20.0.1.0/24, Route Distinguisher: 11.0.1.1:0
 Paths: 1 available
  301
    11.0.1.1 from 10.0.0.2 (0.0.1.1)
      Origin IGP, metric -, localpref 100, weight 0, valid, external, best
      Extended Community: Route-Target-AS:300:0 Route-Target-AS:301:0
      MPLS label: 116507

This route was using 4 FEC entries for each VRF before the change.

switch#show platform jericho ip route 20.0.1.0/24
Tunnel Type: M(mpls), G(gre), MoG(mpls-over-gre),
             vxlan-o(vxlan outer-rewrite info), vxlan-i(vxlan inner-rewrite info)
* - Routes in LEM
D - ECMP is divergent across switching chips
 ---------------------------------------------------------------------------------------------------------
|                                 Routing Table                                           |              |
|---------------------------------------------------------------------------------------------------------
|VRF|   Destination    |     |                    |     |       |                   | ECMP|  FEC | Tunnel
| ID|      Subnet      | Cmd |     Destination    | VID |Outlif |   MAC / CPU Code  |Index| Index|T Value
 ---------------------------------------------------------------------------------------------------------
|1  |20.0.1.0/24       |ROUTE| FEC 32776          |0    |  -    |                   |  -  |49152 |M 116507
|2  |20.0.1.0/24       |ROUTE| FEC 32776          |0    |  -    |                   |  -  |49154 |M 116507
|3  |20.0.1.0/24       |ROUTE| FEC 32776          |0    |  -    |                   |  -  |49155 |M 116507
|4  |20.0.1.0/24       |ROUTE| FEC 32776          |0    |  -    |                   |  -  |49156 |M 116507

The following uses single FEC entry For VPN routes imported to all VRFs after configuring bgp fec skip in-place update event all command.

switch#show platform jericho ip route 20.0.1.0/24
Tunnel Type: M(mpls), G(gre), MoG(mpls-over-gre),
             vxlan-o(vxlan outer-rewrite info), vxlan-i(vxlan inner-rewrite info)
* - Routes in LEM
D - ECMP is divergent across switching chips
 ---------------------------------------------------------------------------------------------------------
|                                 Routing Table                                           |              |
|---------------------------------------------------------------------------------------------------------
|VRF|   Destination    |     |                    |     |       |                   | ECMP|  FEC | Tunnel
| ID|      Subnet      | Cmd |     Destination    | VID |Outlif |   MAC / CPU Code  |Index| Index|T Value
 ---------------------------------------------------------------------------------------------------------
|1  |20.0.1.0/24       |ROUTE| FEC 32780          |0    |  -    |                   |  -  |49152 |M 116507
|2  |20.0.1.0/24       |ROUTE| FEC 32780          |0    |  -    |                   |  -  |49152 |M 116507
|3  |20.0.1.0/24       |ROUTE| FEC 32780          |0    |  -    |                   |  -  |49152 |M 116507
|4  |20.0.1.0/24       |ROUTE| FEC 32780          |0    |  -    |                   |  -  |49152 |M 116507