FAO Layer-3 Switch Users

markwombat · 7 Mar 2007 at 15:47

Hi guys,

if anyone on here uses layer3 switching I am hoping you can provide an answer to the following question.

If one uses tracert to "map" a network do layer3 switches passed through along the way appear in the tracert output?

Many thanks

markwombat.

ruffneck · 7 Mar 2007 at 15:53

yes it does add to the hop count

Dunks · 7 Mar 2007 at 16:40

Yep, they do.

markwombat · 7 Mar 2007 at 16:49

Thanks guys for your replies.

One other query I have about some traceroute results, is that the default gateway of the computers on the network i am "mapping" is never the 1st hop on the traceroute output, in fact even using the

tracert -j default.gateway destination

syntax I cannot get my host(s) to report their default gateway as the 1st hop, the default gateway exists (ping confirms this) but i cannot seem to "go through" it, instead any connections always go through a different router (still within the clients subnet) any ideas on why this could be?

oddjob62 · 7 Mar 2007 at 18:39

Static routes?

bigredshark · 7 Mar 2007 at 21:09

a layer 3 switch will only show up if it's in route mode on those ports, if they belong to the same vlan it'll go straight through it without showing up.

regarding the different gateway as the first hop, if it's a complex network, then it's feasible that the default gateway ip is in fact just a vrrp or hsrp ip and the actual interfaces on the router are different.

thats about all i can think off, static routes are unlikely if it's for all ips

markwombat · 7 Mar 2007 at 21:27

bigredshark said:
a layer 3 switch will only show up if it's in route mode on those ports, if they belong to the same vlan it'll go straight through it without showing up.

regarding the different gateway as the first hop, if it's a complex network, then it's feasible that the default gateway ip is in fact just a vrrp or hsrp ip and the actual interfaces on the router are different.

thats about all i can think off, static routes are unlikely if it's for all ips

Both os these concepts seem like a very plausible explanation of what I am seeing, thanks a lot for your suggestion.