Can we have the LAN interface on the cisco2811 router to be Layer2 interface

Answered Question
May 20th, 2010
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Hi,

I am using a cisco 2811 router.I am running short of Layer3 interface.

Can i use L2 interface on the router for connecting my LAN segment.


To explain in detail.

I have totally 4 L3interface on the router.

2 interfaces will be used for WAN connection

1 intercae will be used for internet connection

1 interface for HSRP

Now can i use the L2 interface for connecting my LAN segment and still have connectivity to 2WAN,Internet,HSRP


Please help


Regards

Arlkumar

Correct Answer by Jonn cos about 7 years 1 week ago

Yes you can do it. Consider HWIC-4ESW as a mini layer 3 switch with 4 ports. Now when you will add this card in ur 2811, you will see 4 L2 fastethernet ports. These ports are layer 2. So you need to create Interface Vlan 1 (SVI) and assign it your lan IP (which will serve as a gateway to your lan machines). Like this


Interface vlan 1

ip address 10.0.0.1 255.255.255.0

no shut


Now all the L2 ports of HWIC are part of vlan 1 and therefore part of this SVI.


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glen.grant Thu, 05/20/2010 - 05:00
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  Please clarify what you mean by a L2 interface .  Do you have like a 4 port hwic module installed ?  If so then yes you can run your lan on that as you can route thru that card by using configured SVI's .

arulkumar80 Thu, 05/20/2010 - 05:16
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Hi,

Can I assign ip address if I am using hwic-4esw.


Regards

Arulkumar

glen.grant Thu, 05/20/2010 - 05:54
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  Yes you would create a layer 3 SVI  and a Layer 2  definition in the vlan database and then put the port on the card into that vlan ...

Correct Answer
Jonn cos Thu, 05/20/2010 - 11:48
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Yes you can do it. Consider HWIC-4ESW as a mini layer 3 switch with 4 ports. Now when you will add this card in ur 2811, you will see 4 L2 fastethernet ports. These ports are layer 2. So you need to create Interface Vlan 1 (SVI) and assign it your lan IP (which will serve as a gateway to your lan machines). Like this


Interface vlan 1

ip address 10.0.0.1 255.255.255.0

no shut


Now all the L2 ports of HWIC are part of vlan 1 and therefore part of this SVI.


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chris.rae07 Thu, 05/20/2010 - 17:45
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Hi Arlkumar,


You can convert the swtich ports in an etherswitch module to Layer 3.


You can achieve this by the following commands-:


router(config)#int f0/1

router(config-int)#no switchport

router(config-int)#ip address ........



Hope this helps

Chris

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