Tue, Dec 27, 2005 at 12:27:52PM +0100, Sylvain Coutant wrote:
Hi,

I think this "depend on" is a nice feature - but I would not
use for "100% fail save" connections.

Why not ? It has been coded for this purpose

No. It is a hack to make it possible to use two routers at an IX where you
only get one IP. If your master router goes belly up all sessions are
dropped and opened on the backup box. This results in a route flap.

You must take into account,
that the session will go down if you trigger a failover.

course, this is the basic of a failover between two routers.

By using two IPs you can do failover without losing all routes on
failover. This is in my opinion the prefered way of doing it.

This
might be acceptable for some kind of sessions (peerings, backup links)
but may be undesirable for "main" (transit) links.

This is *highly* desirable in any situation where one router goes down for any reason.

If you are using bgpd you can add redundancy to your network in a more
flexible way than via carp. Terminate your upstreams on multiple boxes run
an IBGP mesh and you get failover too.

Look, we're in a *failover* case. Session going down for 10 seconds is
better than session going down until someone brings it back up

The session probably down for more than 10 seconds. Even two bgpd take a
bit more than 10 seconds to sync the RIB.