routing enabled w/o ip default gateway or ip route command

[Ken Yoon]

Hi,

We have two catalyst 3560 switches running  c3560-ipbasek9-mz.122-58.SE2.bin      

They are connected using etherchannel using gi 0/21 -  24 interfaces.

on 3560-1 switch, there isn't any ip-default gateway or ip route configured. It only have 1 interface vlan configured.

on 3560-2 switch, there is ip default gateway configured along with 1 interface vlan.

What i dont understand here is that, i can reach out to other subnets from 3560-1 switch in which the routing is not enabled?

Can someone explain it to me how it's possible?

Thanks!

[Gregory Snipes]

Could you post up the configurations you are using?

[glen.grant · Accepted solution]

If the one 3560 is doing the routing and is trunked to second 3560 routing does not need to be turned on  for the 2nd 3560  and the address on the 2nd 3560 is just to manage the switch.

[francisco_1 · Accepted solution]

The default gateway on the switch is for management purposes only. If you don’t input a default gateway on the switch, you won’t be able to manage it via IP. the Hosts connected to the 3560-1 have their gateway set, the switches uses it layer2 cam table (forwarding table this is not a layer3 routed table)  to forward frames to the destination.

[Ken Yoon]

Thanks guys,

I think as long as switches are connected using Trunk, it use other switch's CAM table to get the next hop. So, i think both of you are correct to the question. Thank you.

BTW, I didnt even unstand the difference between the ip default gateway and ip route 0.0.0.0

Here's a linke to the doc which explains the difference between them.

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094374.shtml