The RFC that had all of the generic methods that were known at the time
of publication is RFC5715.
The two phase methods were in section 6.2 (near-side) and section 6.3
(far-side). The first describing tunnelling the traffic towards the
repair (and continue to use the repair), the second describing
tunnelling traffic towards the destination. For the purposes of this
discussion source routing of all flavours can be considered a type of
tunnel.
If this approach is a new genetric two phase method, it would be
useful to articulate it in general terms.
The type of topology that I was trying to explain in the meeting is as
follows
A-B-C-D-E-F-H-I-J.....W
| |
| |
+------X-Y-Z----------+
All costs are 1 and Y has failed.
Traffic to Z can enter enywhere, and is protected by X.
When the network starts to converge ALL the routers A..J will need to
update their fib to forward towards Z via W rather than towards X via A.
If they do this in a random order as would be the case without LF
convergence then you may precipitate microlooping.
What you need to do is to force the packets toward either X or Z using a
tunnel, or a source routed path, and as far as I can see you need to do
that at every point of potential entry into the network, in the above
case A..J, else you risk a microloop.
Now I suppose that if ALL packets were source routed, then you could
consider that the network was constantly in the first phase, but I think
that you would need to use strict source routing, rather than loose
source routing else it reduces the the problem I describe above.
- Stewart
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