Are they the same thing?

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Layer 3 - Network Layer handled by a Router
Layer 2 - Data Link Layer handled by a "switch"

Sometimes a engineer will refer to a layer 3 switch because there is either a add-in module or card in a multi-layer switch, one that is capable of handling both functions but in a seperate manner. The layer 2 and 3 modules are configured seperately.

Currently the 4006, 5x00, 6x00, and others can handle Layer 2 and 3 functions but only with the addition of another module.

Help?

__________________
Nothing in this world can take the place of persistence. Talent will not; nothing is more common than unsuccessful people with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. The slogan “Press On” has solved and always will solve the problems of the human race.
—Calvin Coolidge

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Hi,

I'll take a crack at this, too.

A Multi-Layer Switch can switch datagrams or packets based on information other than just layer 2 or 3 ie . . . layer 4 info ( UDP port, type of traffic. )


Now don't confuse that with Cisco's term 'Multi-Layer Switching' It is different than that. Multi-Layer switching encorporates a Layer two switch and a Layer 3 router ( internal or external to the switch )working together to greatly improve switching speed.

The Layer 3 part can either be an external router, ( usually high end ), or an internal router card installed into the slot of a switch. The Layer two part have a MLS-SE ( Multi-layer switch switching Engine ), and both this MLS-SE and the router use MLSP ( Multi-Layer Switching protocol ) to operate:

It works kinda like this:

The router part first looks at the very first packet in a flow, defines its destination, caches it, - the switch figures that every packet in the flow is going to the same place and each packet after that is switched using Layer 2 info, rather than routed - much faster than routing every single packet.

A Layer 3 switch would be a switch that is Layer 3 aware, and could perform the previous process. A Layer 3 switch would most likely have the router card as part of its supervisor engine - If it were a switch connected to an external router, performing Multi-Layer Switching, that switch would just be CONNECTED to a router, and not a Layer 3 switch itself.

Either I totally helped you out, or totally confused you.

Peace,

Justin

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Thank you Justin2112!
You mean that Cisco cat 4006 with supervisor engine III,cat 3550 switch are layer 3 switch? I know that we can implement multi-layer switching (mls) on cat 5000 or 6000 serials switch with a mls-rp or a external high end router.But how do this on cat 4006 with supervisor engine III or cat 3550 switch?

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Two ways on 4006
1. 4232 layer 3 card
2. Sup III card recently released.

6509/13
MSFC add-in card.

5x00
Either RSM /RSFC


! On the 4006 Switch with the 4232 or Sup III
! implement
interface port-channel 1.n
! The n refers to the vlan
! Do not modify Port-channel 1
encapsulation dot1q n (use n as above)
! the switch side only supports dot1q.
ip address x.x.x.x x.x.x.x

! set up :
interface gigabitethernet3
channel-group 1
interface Gigabitethernet4
channel-group 1

The RSM/RSFC or the MSFC on the 5x00 and 65xx routers is a much simpler config.

interface vlan x
ip address x.x.x.x x.x.x.x
! that's it!


There was another post where I had laid this all out if I find I add a note.

Use this L3 config. if you like it has been working on 6 devices since the 4232 was released. I've been informed that there isn't a significant change with the sup III except the additional routing card isn't required.


There are several routers that support MLS attached to a comperable switch. I have used the 7500 series to connect to a high-end switch to provide Multiple Layer Switching mls-rp.
That didn't seem to be the question you were asking. As Justin indicated there is a 'difference'.

Sometimes less of a answer is better. Hopefully this is helpful.

__________________
Nothing in this world can take the place of persistence. Talent will not; nothing is more common than unsuccessful people with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. The slogan “Press On” has solved and always will solve the problems of the human race.
—Calvin Coolidge

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O,But this is for inter-vlan routing,not for multi-layer switching(mls) configuration.on cat 4006 with supervisor engine III,or cat 3550,we cann't find that command like this on cat 5000 or 6000's router module:
Router(config)#mls rp ip
I just want to konw how to implement the multi-layer switching.Anyhow,thanks.

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