Standard Catalyst switch vs. Enhanced routing version

[gdegodoy]

I have question regarding the Cisco catalyst switches with the enhanced routing option.

As I understand it to do layer 3 routing between vlans on a standard catalyst switch IOS requires me to configure a port on the switch with 802.1Q, plug that port into a seprate router and configure the router's port (also configured with 802.1Q) as a 'router on a stick' for each vlan i need to route. Then any additional switches I want to add to the network I would simply trunk them back to the switch that has the router plugged in so i could have inter-vlan routing. Does this sound correct?

Now if I used a switch with the enhanced layer-3 IOS (A WS-C3560G-24TS-E for example) would i be able to remove the extra router from the design? would the packet routing go at the speed of the back-pane of the enhanced switch, rather than the wire-speed of the connection to a external router? I would also be able to get a gigabit SFP for each of my additional switches (3500XL's) and plug them into a trunked port on the 3560 thus giving a full gigabit trunk to each access layer switch.

Or would a router on a stick be a fine solution for inter-vlan routing? There will be a need for a integrated services router in the future to act as our CME for this site, so we will be purchasing a router anyways.

[pkhatri]

Hi,

If you used a L3 switch, you do not need the router, if all you require is inter-vlan routing. The packets will be iter-vlan routed at whatever rate the switch fabric supports (same as the rate used for L2 switching).

Pls do remember to rate posts.

Paresh

[ankurbhasin · Accepted solution]

Hi Friend,

If you have layer 3 switch with standard image then also you will be able to configure intervlan routing on layer 3 switch.

Enhance image on layer 3 switch will let you configure routing protocols like ospf, bgp and enhance qos features whih is not possible with standard images.

But just for intervlan routing any layer 3 switch like 3550,3560 will let you achieve inter vlan routing without using external router.

Have a look at this link for intervlan routing on layer 3 switch like 350/3560 switches

http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a008015f17a.shtml

HTH, if yes please rate the post.

Ankur

[gwhuang5398]

Just for inter-vlan routing, a L3 3560 switch can very well handle it. When you IP address each vlan on the switch, each vlan would show up in the 3560 routing engine as "connected subnets", and will be routed between each other. You can simply see a L3 3650 as a router and a switch collapsed together.

However an dedicated external router (usually a higher end model) does have some benifits besides just inter-vlan routing. For example running BGP with outside networks for Internet, Extranet, etc. Normally you don't want to have all that in a L3 3650 although it is capable of running routing protocols. From this perspective, it's more up to your particular network needs.

Hope this helps.

Gary