Re: [6man] New Version Notification for draft-nordmark-6man-impatient-nud-00.txt

[Thomas Narten <[e-mail]>]

Ray Hunter <[e-mail]> writes:

> Are there any implications for different nodes having different NUD 
> timeout behavior on a link, and this no longer being symmetrical?

I do not think so.

> e.g. 1. Say Node A (router) declares node C (end node) unreachable but 
> Node B (alternate back up router) has not yet timed out node C?

IMO, this should not be an issue. 

> Now the case of router failover....

> e.g. 2. Say Node A (end host) declares node B (router) unreachable 
> locally, but node B (router) is still up and running but has not yet 
> timed out Node A.

At this point there is already a problem, because packets  do not seem
to be flowing. The sooner both peers recognize that the path is not
working and find an alternative the better.

But by definition, the two peers will *never* be able to determine
this situation at *exactly* the same time. That is, there will always
be cases where NodeA determines NodeB is unreachable before NodeB
detects NodeA is unreachable (and vice versa).

While it would be better to have both peers determine that the path to
each other is down ASAP, there is not and has never been a requirement
that both peers detect that a path is not working at the same time.

Thomas