What's the difference?

notgoing2fail

Not sure where this question goes so I'll post it here.

What's the difference between a router having switch capabilities like an 1811 or any router with a switch module versus a L3 switch with routing capabilities?

Other than the obvious that a switch has more ports....

CiskHo

I'm not 100% sure... but I would guess that an L3 switch would be more efficient (faster) at switching frames than a router with switching module would be, and vice-versa in regards to routing packets. I would think it just comes down to what the hardware was designed to do. As far as features go I am unaware of any notable differences but I'm no expert.

mikem2te

CiskHo wrote: »

I'm not 100% sure... but I would guess that an L3 switch would be more efficient (faster) at switching frames than a router with switching module would be, and vice-versa in regards to routing packets. I would think it just comes down to what the hardware was designed to do. As far as features go I am unaware of any notable differences but I'm no expert.

I think you are right. I believe the switchports will forward traffic at wire speed if the communicating ports are on the same VLAN. If traffic is passing between two VLANs then the packets hit the routers processor and therefore performance will suffer.

In a layer 3 switch all frames are switched in the ASICs so inter vlan frames should get switched at wire speed.

There are functional differences also. I don't think it is possible to configure a port as a true routed port using the 'no switchport' command unlike a true multilayer switch, all routing is done using an vlan SVI.

EDIT : I found a Q&A document for the HWIC-9ESW which may answer some questions-

http://www.cisco.com/en/US/prod/collateral/routers/ps5853/prod_qas0900aecd8016c026_ps5854_Products_Q_and_A_Item.html

DevilWAH

in general a layer 3 switch only deals with Ethernet. where as a router can deal with multiply protocols.

however a layer three switch is a router (or the part of it that is routing the data at layer 3 is)

Put simply

a router switches data at layer 3
a switch switches data at layer 2

layer 3 switch is a market term, its correct description would be 'a router and switch integrated in to a single hardware package'. but that does not look so good on the brochures.

The is a cross over between the to now in terms of hardware packages, and you do see more and more features crossing over.

as people have said switches are more efficient at switching packets than routers general, and they don't have such advanced routing features or things like VPN abilities.

generally a layer 3 switch is faster and has many layer2 functions, but less layer 3 features, where as the opposite is true of routers.

but yes don't get the names confused with the functions.

a layer 3 "switch" is only a switch at layer 2, when it moves to running at layer 3 it is a router. the same is true of a router.