BFD over p2p transport links

Tim Durack tdurack at
Fri Feb 5 15:47:27 UTC 2010

On Fri, Feb 5, 2010 at 9:45 AM, Serge Vautour <sergevautour at> wrote:
> Hello,
> I'm being asked to look into using BFD over our P2P transport links. Is anyone else doing this? Our transport links are all 10G Ethernet (LAN-PHY). There's no alarming inside of LAN-PHY like there is in SONET. The transport side should propagate a fiber break by stopping to send light on both ends. This is enough to cause the router interfaces to drop and for protocols to converge.

We only use BFD on L2 circuits.

Ethernet auto-neg includes limited link-fault signalling. It's not as
good as SONET, but it will detect link-failure/one-way link.

> Since LAN-PHY doesn't have any built end-end alarming, some folks believe that we may encounter situations where a fiber break doesn't cause interfaces do go down. Convergence would then have to wait for IGP hellos to detect the problem.

Have not found GigE 10GigE to be a problem over fiber.

Have found BFD to be problematic depending on the implementation and
CPU load of your equipment.

The closer you can stay to the physical layer, the better off you are.

> Is anybody else running BFD over 10G LAN-PHY transport links? Any comments around BFD for this application in general?
> Thanks,
> Serge
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Sent from Brooklyn, NY, United States

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