On Fri, 2008-11-07 at 08:28 -0500, Drew Weaver wrote: > We have a Simple L3 switch (I think it's a 2960G) that we need to do > some even simpler fault tolerance and load sharing on.
They're not 2960s, since those are L2 only. Maybe 3560s? > We were going to connect this switch to 3x switches upstream and then > do something like this: > > ip route 0.0.0.0 0.0.0.0 g0/32 gwip > ip route 0.0.0.0 0.0.0.0 g0/33 gwip > ip route 0.0.0.0 0.0.0.0 g0/34 gwip As Steinar mentions, you should use a specific next hop address. I assume that the three interfaces are routed ports, or that they use seperate VLANs. What's upstream? > When we were testing we noticed some (well, quite a bit) of strangeness > with traceroutes and the like (many multiple hops for the same, hop.. > etc) What exactly do you mean with "many multiple hops"? Different answers for multiple requests with the same TTL (same hop in traceroute) is not all that unnormal for multiple paths -- each path is elegible for the traffic, so each next hop router can answer. The L3 switches (i.e. not software based routers) typically use a hashed load sharing algorithm, resulting in per destination or per source (or a combination) load sharing. They could also include the ports in the hashing, meaning that a traceroute using a different source port per probe would result in different next hops. If this is unwanted, you can change the algorithm to something that doesn't include L4 ports. > is there a better way to do what we're trying to achieve? > > We were thinking about maybe doing VRRP on the 3 switches upstream but > then we would only be using 1Gbps and the goal is to be able to use "a > little more than" 1Gbps. You _could_ use GLBP as a load sharing enabled equivalent of VRRP. Don't know is your hardware/software supports it though. And equal cost multipath (ECMP) would be my preferred choice if possible. Regards, Peter _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
