Advanced L3 forwarding features, routed (WAN) port vs SVI

[remco.overweg]

Why can't an SVI be used for advanced L3 forwarding features, but a "routed" (EHWIC) wan port can?
I'm asking this, because since almost all ISR G2  (Cisco 8xx, 19xx, 29xx, 39xx) routers are using a generalized CPU platform, so the CPU is involved in either case for this kind of intelligence. So what's the kicker?

[Jon Marshall · Accepted solution]

Do you mean when you have a switch module installed in the router ?

If so it is because the switch module is actually a L3 switch in a form that can be inserted into an ISR. So it is hardware based switching (L2 and L3) and as such has the same limitations as a standalone L3 switch.

So the general CPU isn't involved when packets are forwarded on the switch module and that's why you can't run some features.

Or maybe I have misunderstood your question ?

Jon

[remco.overweg]

Damn, Jon, thats the answer i was looking for! (could you please give me the information where you got that, because i looked for that quite long), big thanks!

[Jon Marshall]

could you please give me the information where you got that, because i looked for that quite long

To be honest it's just something I know but if you use the link below and select any of the switch module data sheets it tells you what switch the module is based on eg. 2960, 3560 etc.

Jon