Can I enable BFD for VLAN interface?

[frank]

Can I enable BFD for VLAN interface as I am not seeing the BFD command under VLAN interface as following?

CDCCORCSW003(config)#int vl202

CDCCORCSW003(config-if)#

CDCCORCSW003(config-if)#bfd ?

% Unrecognized command

CDCCORCSW003(config-if)#int gi8/1

CDCCORCSW003(config-if)#bfd ?

echo Use echo adjunct as bfd detection mechanism

interval Transmit interval between BFD packets

neighbor BFD neighbor configuration commands (simulate client)

CDCCORCSW003(config-if)#

All the BGP neighbors are established on trunked interface per VLAN.

[Giuseppe Larosa]

Hello Franck,

an SVI is up/up until there is at least an associated layer port in STP forwarding state and STP manages the link redundancy (if any).

This is the autostate feature.

probably BFD cannot be used on an SVI as you show in your log.

BFD packets might be required to go out multiple physical interfaces associated to the L2 Vlan if enabled at the SVI level.

I've just tried to list possible reasons for lack of support and the root cause should be the semi-logical nature of the SVI.

Hope to help

Giuseppe

[frank]

Giuseppe, Thanks for the reply.

I agree with you that BFD might only works on PPP kind of link not on L2 VLAN and that is why there is not BFD command under VLAN interface.

In this case would it help the BGP convergent time if I only enable BFD for BGP neighbors? Guess not as BFD needs physical reachability.

[Map23]

Hello Frank,

did you find  solutions of your problem ? I have now the same issue because I have to configure BGP neighbor with BFD on Vlan interface. I can set BGP neighbor with BFD but I can't set "bfd  interval" on Vlan Inteface.

Can anyone help me ?

My IOS is 12.2(33) SRC

Thanks

[Vishesh Verma]

Hi,

As per this doc, BFD over SVI is supported on all the hardware platforms where BFD is supported.

http://www.cisco.com/en/US/docs/routers/7600/ios/15S/configuration/guide/bfdsvi.html

Also, 12.2(33) SRC is very old code, and has already gone out of support for most stuff.

http://www.cisco.com/en/US/prod/collateral/iosswrel/ps8802/ps6970/ps6922/end_of_life_notice_c51-571251.html

You must upgrade the code, to support this feature.

-Vishesh

[Map23]

Thanks Vishesh,

I think that I have to upgrade my code too, but I don't understand why on that documents:

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bfd/configuration/12-2sr/irb-12-2sr-book/Bidirectional_Forwarding_Detection.html

That sentence is present:

BFD Support for Nonbroadcast Media Interfaces

In Cisco IOS Release 12.2(33)SRC, the BFD feature is supported on nonbroadcast media interfaces including ATM, POS, serial, and VLAN interfaces. BFD support also extends to ATM, Frame Relay (FR), POS, and serial subinterfaces.

When I read that I suppose that BFD is avaible on my Vlan interface, but basic interface command "bfd  interval" is not present.

I don't know why...

Maybe is better send a message to TAC.

Thank for your help,

Marcello