Solved: Hardware question

John Blakley · ‎04-02-2009

I know a L3 switch can do routing, but is it feasible to be a router? Does Cisco make an ISR that allows being a core switch and router where you only need the one device?

Thanks,

John

HTH, John *** Please rate all useful posts ***

Jon Marshall · ‎04-02-2009

The 6500 supports some WAN Interface cards and the 7600 supports switching modules but these are rather expensive solutions.

The trouble with using a switch to terminate WAN connectivity is that you then start running into limitations on the switch. 2 examples -

1) QOS is nowhere near as fully featured on a switch than on a router

2) NAT - only 6500 can do NAT and most enterprise have a need for NAT whether they like it or not.

Personally i would stick with the one router/one switch solution. And bear in mind that even if you went with an ISR and etherswitch module this is really only a router and separate L2 switch shoved into the same chassis :-)

Jon

View solution in original post

Jon Marshall · ‎04-02-2009

John

Not sure i fully understand. A L3 switch is a router as well as a L2 switch but i'm guessing that is not what you are asking.

As for ISR in core, well you can use etherswitch modules in the ISR for L2 connectivity but generally speaking in the core you want devices that switch/route at wirespeed if possible, hence the reason for using L3 switches.

Jon

John Blakley · ‎04-02-2009

Well, the question that I was asked yesterday was, "Can we replace our existing router and core switch stack (3750) with an all-in-one device."

Problem 1: The 3745 (router) has a DS3 card in it (3750 won't support this, not sure if any switch would).

Problem 2: The other card in our 3745 are vWIC2s, and I'm not sure if other switches would support that.

So with the above two problems, the only thing I could think of that would allow me to bring a circuit directly into a switch would be an ethernet handoff from a provider, unless there's a switch that allows these types of cards.

Thanks Jon!

John

HTH, John *** Please rate all useful posts ***

Jon Marshall · ‎04-02-2009

The 6500 supports some WAN Interface cards and the 7600 supports switching modules but these are rather expensive solutions.

The trouble with using a switch to terminate WAN connectivity is that you then start running into limitations on the switch. 2 examples -

1) QOS is nowhere near as fully featured on a switch than on a router

2) NAT - only 6500 can do NAT and most enterprise have a need for NAT whether they like it or not.

Personally i would stick with the one router/one switch solution. And bear in mind that even if you went with an ISR and etherswitch module this is really only a router and separate L2 switch shoved into the same chassis :-)

Jon

Joseph W. Doherty · ‎04-03-2009

As Jon describes in his posts, within the Cisco product mix, on the low end, L3 switches and routers performance and features usually vary much. (On the high end, there's a "difference" issue between the 6500 and 7600. BTW, some Brand X vendors offer single devices that are more switch/router "integrated" as a competitive feature vs. Cisco.)

Besides the L2 switch modules that can be placed into some ISRs, Cisco also offers L3 switch modules that can be placed into some ISRs.

PS:

Lastly, there's also Cisco's Metro switch series. These usually offer additional software features, but might still be very limited in typical WAN connectivity.