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Community Member

LAN Problem

Hello everyone

Let me explain my very specific problem. I have two locations connected with fiber optic. Lan Switches are 6500 series and routers are 3700 series

My network looks something like this:


At location 1 there is one broadcast domain and network At location 2 we have and again no additional VLANs except default VLAN1.

Now the problem is that company wants to implement ISA 2004 NLB which requires that both of the ISA servers are in the same logical network and same broadcast domain. One ISA will be at location 1 and another at location 2.

So I need to somehow make a port on Cisco6500 at location 2 to be in the same broadcast domain as location 1 is.

What are my options? I was thinking about dot1q tunneling but I'm still trying to figure out will that solution impact current network and current routing between these two sites.

Any help is more than welcome...

Thank you all...



Re: LAN Problem


try for bridging....i think it will solve your issue...



Community Member

Re: LAN Problem

Ok, I was thinking about bridging too, but I need to configure bridging and not to connect this two broadcast domains into one.

I tried to create interface tunnel, but I realised that bridging is not allowed between physical interface and tunneled interface.

How exactely to create bridging?

Remember, everythig else must retain same. These two networks ( and must exist and routing must continue between them.


Re: LAN Problem

ok you can do an ATOM connection between the 2 vlans that are on each site. You can use L2TPv3 to accomplish this as you are not running mpls. First try the command pseudowire to ensure that your IOS can do an L2TPv3 command. If you can then you can just xconnect the two vlans together and your done.


Re: LAN Problem

One question before I provide my point of view as to the options available to you, do you have MSFCs on the 6500s? If the answer to that is yes then I would like to ask you why you are using 3700s and not terminating the inter-site fiber link directly on the 6500s?

With your existing setup you pretty much have the following options:

1) Convert the 3700 to 6500 links on each site to dot1q trunks. Then put the ISA2004 heartbeat links on a dedicated VLAN. Use L2TPv3 (as suggested by Robert) to extend this VLAN across the routers.

2) This solution also involves converting the 3700 to 6500 link on each site to a dot1q trunk. Additionally, the link between the 3700s will also be a trunk carrying two unique VLANs. One VLAN will be a routing VLAN to handle routing between the 3700s. The second VLAN will be bridged with the ISAVLAN on each 3700.

The second solution is based on the assumption that the link between the 3700s is a Gig link over dark fiber or some other means of transport (like Ethernet over SDH or DWDM). If that is not the case then option 1 is probably the only choice you have.

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