BFD and Service provider

[news2010a]

Hello,
Imagine I have  MPLS CE routers connected to MPLS provider. In some sites I have NxT1, other sites Ethernet various speeds.

All Cisco C2900 or C3900 ISR G2 devices. CE-PE routing protocol in all sites is BGPv4.

Issue:

- Service provider tells me BFD (fast detection in case of WAN link failure) is available only for certain circuit speeds. I did not understand that statement very well. It seems provider is saying that BFD is available as a feature only on Ethernet above 20Mbps for example.

Question:

Do I necessarily need service provider PEs to be compatible with BFD if I my CE routers are all Cisco and compatible with BFD both on hardware and IOS version? From what I can tell the configuration of BFD could take place in my MPLS CE routers and that is it.

The only thing  I can imagine if that if provider is running Juniper routers for example the config would differ.

Please let me know what I am missing.

I

[Giuseppe Larosa]

Hello Marlon,

if the service is an MPLS L3 VPN your CE devices peer with their respective PE nodes and BFD can only be run between adjacent devices.

The MPLS SP has made a choice to make BFD available only for access links of at least 20 Mbps speed with  Ethernet handoff.

This choice has also some technical reasons behind it: each platform can execute a finite number of BFD sessions (platform and IOS dependent) so they don't want to use BFD on slower access links to save room for the links with greater income.

I don't know if BFD is supported over point to point GRE tunnels, if it is this might be a possible solution in which you need a full mesh of p2p GRE tunnels between all CE nodes and to run BFD over them.

What are your convergence requirements?

Hope to help

Giuseppe

[news2010a]

Thanks. That is fine about the 20Mbps limitation  - OK, most links could be upgraded to Ethernet 20Mbps.

My company has contact center agents in many  locations, using a contact center in the cloud type of application.

Currently there are no backup circuits in the remote office. Therefore I am proposing an IPSec tunnel to the headquarters.

The main WAN circuit is MPLS. If it goes down, people in my company are complaining waiting up to 90 seconds for BGP to detect the link is down is too much for the contact center folks. Therefore that is why I thought if we could enable BFD and detect link is down fast, then the route via the IPsec tunnel would be used.

[Giuseppe Larosa]

Hello Marlon,

BGP timers can be set per BGP session and you can reduce them to 1sec hello, 4 sec hold time on your side and they will be effective.

This might be enough for your application or not. Total convergence time depends on SP internal settings.

Sites that can use BFD will receive a better treatment.

Hope to help

Giuseppe