[j-nsp] MPLS fast convergence without link information

[Mark Smith]

On Thu, Dec 29, 2011 at 6:45 PM, Phil Bedard <philxor at gmail.com> wrote:
> BFD on the IGP session would be the best option.  We currently run ours at 300x3 on Juniper boxes and lower on some other platforms with better hardware processing of BFD packets.   If you are using aggregates something like 802.3ah may work better as BFD control traffic has a tendency to just take a single link on Junipers.  It is honor miss though whether L2 circuit provider can tunnel that traffic.

Thanks for comments.

Correct me if I am wrong, but doesn't enabling BFD on the IGP cause
IGP to reconverge in case of fault?

Is there any (reasonable) way to utilize link-node-protection or FRR
if link state information is not usable between MPLS routers? Or are
these fast repair mechanisms only usable in case of dark fiber (or
copper)?

To put this in another way: I cannot expect sub-second recovery times
unless the failure detection is triggered by interface link down?

I had impression that one could use BFD to trigger facility backup
(bypass LSP) in sub-second time (e.g. 3x 50ms). This appears to be
incorrect.

I would not expect the L2 service provider to be able to tunnel
ethernet OAM (CCM etc) traffic.

I wonder why haven't I found good information about this in the 'net.
Am I blind or do all major players always have dark fibers (or
similar) at their disposal? How about unidirectional fiber failures?
At least in some cases (e.g. all autonegotiation stuff disabled)
unidirectional fiber results in link up on the other (where rx sees
light) end and link down on the other. How are these handled?


I really appreciate comments and discussion.