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Home > Archive > CCNA > June 2002 > what is the difference between layer 3 switch and multilayer switch?
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what is the difference between layer 3 switch and multilayer switch?
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| cahillrobert 2002-06-25, 8:59 pm |
| 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? | |
| Justin2112 2002-06-26, 4:33 pm |
| 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? | |
| cahillrobert 2002-06-26, 8:22 pm |
| 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. | |
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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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