WAN Eth. Port on 2821

Unanswered Question
Jun 23rd, 2009


I have one 2821 Router with 2 Gig port inbuild. but I need another minimum 4 port because more 4 locations would be added to this router. How do I connect extra eth wan port in 2821 router.

I have this problem too.
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Giuseppe Larosa Tue, 06/23/2009 - 23:59

Hello Goutam,

if you have also a LAN switch you can connect sites to the LAN switch and you can use one GE port with subinterfaces: you just need one vlan for each remote site on L2 lan switch where you put the port where the remote site link is connected and a L2 trunk between the router and the layer2 switch.

if you haven't the external switch you can think of getting one or to get an etherswitch module to install on the router.



but it can be cheaper an external switch with the setup I've described above.

Hope to help


goutam_04 Wed, 06/24/2009 - 00:08


I have another five offices where using 1841 router. and in my main office 2821. I would like to connect between main office to other 5 offices through leased line on Metro Ethernet.

Five physical links will be terminated to 2821 router, for those I need 5 WAN eht. port on 2821. which port or slot would be the same.

Giuseppe Larosa Wed, 06/24/2009 - 00:24

Hello Goutam,

buy an etherswitch module follow the link in my first post.

I would use an external switch as I described in my first post and I would use multiple Vlans to multiplex the remote sites to your GE port.

Actually the metro ethernet service provider can do this for you allowing to reach each remote site on a different vlan using a single GE.

I would ask them if they can do this so you can evaluate also this solution.

Hope to help



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