[j-nsp] UDLD on Juniper ?

[Saku Ytti]

On (2015-07-08 18:23 +0200), james list wrote:

Hey,

> A customer of mine asked for migrating a port-channel from a C6500 towards
> another C6500 with UDLD to an MX towards a C6500, customer would like to
> keep UDLD to prevent faults.

Prevent what type of faults? UDLD is done in all platforms that I know off
from the control-plane, this introduces some new failure modes.

Typically what is attempted to fix is having unidirectional link, which can
cause very serious problem in L2 networks running STP.
However, point-to-point ethernet link should guarantee bidirectionally unless
specifically broken by turning off autonego or such. If ethernet links detects
loss of link, it'll assert RFI, and far end can use this to go down as well.

Same RFI is used optionally in Juniper to force CPEs WAN port down when
l2circuit in PE goes down (without putting local interface down).

-- 
  ++ytti