[c-nsp] layer 3 switch vs router....

[Arie Vayner (avayner)]

Scott,

The main issue with "layer 3 switches" is that they are built for LAN environments. The MetroE circuit is most likely a sub-rate link (physical rate is 1GE, downstream SP rate limits to <1Gbps).
It means that on your egress port to the MetroE link you need to perform H-QOS, with egress shaping and a child QOS policy for the different traffic classes.
Regular LAN switches usually do not support egress shaping.

The exception would be the different "Metro" switches like the ME3600 or ME3800, which could be a good option in your case.

Other differences between "routers" and "switches" are related to feature support... switches are usually hardware based, and if a feature is not supported in the hardware ASICs, you would not be able to really use it (it might work, but not scale). Examples could be things like IPSec (even though many switches now have 802.1ae MACsec), scaled up routing table sizes etc.

Arie

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Scott Voll
Sent: Wednesday, October 03, 2012 08:25
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] layer 3 switch vs router....

Can anyone fill in the blanks for me?

We currently have MetroE connections to all our remote sites.  we use a
3845 at the core and 38xx or 28xx to all the remote sites.  Current connections are >200mb.

Remote sites are Voice Routers, and do FW / IPSec VPN backup to the Core in case of WAN failure.

If I move my remote site Routers back, and put a Layer 3 switch in front to do the routing (wire speed) what will I lose?

Do I lose QoS flexiblity?

I should still be able to do my backup VPN with the current Router as it only has about a 20mb backup link and will still be a routing peer.

Is there anything else I might loose by moving to a Layer 3 switch rather than a 2951?

Any suggestions as to a Layer 3 switch to use?  3750x?  I only need 48 1 gig ports.  49xx? Other thoughts?

TIA

Scott
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