Cisco IP routing on L3 switches

[medinseto]

I'm trying to make sure I understand the full capability of using the "ip routing" command on a L3 switch. Enabling "ip routing" ONLY enable inter-vlan routing assuming the SVI of the switch is the gateway of the VLAN. If I have some switch down the line with with SVI for VLAN 1 and 2, traffic is still being routed all the way to the gateway of the VLAN before being routed to the other VLAN.

[Flavio Miranda]

Hi

 What do you mean by "Switch down the line"? Do you mean if you have a switch connected to the L3 switch?

[Jon Marshall]

Do you mean if the gateway of the client is a different switch ? 

If so then yes for traffic coming from the client to remote subnets. 

Jon

[Richard Burts]

I agree that the question in the original post is not clear. It describes a L3 switch with ip routing enabled. And it describes another switch that has SVI for vlan 1 and 2. It does not tell us whether the other switch has ip routing enabled (though the suggestion that it has multiple SVI would seem to imply that ip routing was enabled). It does not tell us whether vlan 1 and 2 are present on this switch or are just on the other switch. And it does not tell us whether the 2 switches are exchanging any routing information.

We can describe in general how it could work. And if the original poster is still not clear then they should post clarification of the question. When you enable ip routing on a switch it will forward packets between and connected subnets/vlans. If the switch has additional routing information (which might be from static routes configured on the switch or might be from the switch participating in a dynamic routing protocol) then the switch can also forward packets for remote subnets/networks.

[Joseph W. Doherty]

" Enabling "ip routing" ONLY enable inter-vlan routing assuming the SVI of the switch is the gateway of the VLAN."

No, it does as the command suggests, i.e. it enables IP routing.

IP routing includes routing between SVIs on that L3 switch, but they don't have to be gateways.  IP routing will occur between any/all IP interfaces on the switch (NB: although, by default, only between IP interfaces within the same VRF, if VRF is supported on the L3 switch), which besides SVIs, may include "routed interfaces".

IP routing should enable usage of static routes and often will enable usage of some dynamic routing protocols.

"If I have some switch down the line with with SVI for VLAN 1 and 2, traffic is still being routed all the way to the gateway of the VLAN before being routed to the other VLAN."

Maybe, maybe not.  Certainly (and usually) for traffic to "jump" between VLANs, IP interfaces (often SVIs, but, and/or, could be routed interfaces too) are needed on those VLANs and routing needs to "know" of the IP networks hosted by the VLANs and how to "route" traffic between them.

With @Richard Burts, it's unclear what your topology is for your last statement, and capabilities of the downstream switch.  If the downstream is strictly L2, then, generally, the traffic needs to transit a L3 interface.  If that switch is also L3, with routing enabled, it's an "it depends" answer as it also "it depends" on the network setup.  For example, if hosts are using "gateways", they will initially send their non-local network traffic to that gateway, but that gateway could respond with a "redirect" to another L3 interface reachable on that network (i.e. L2 reachable) which is NOT a gateway.