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VPN with different default gw


Hi everybody,

I have done a national VPN with cisco series 800 router using site-to-site GRE

tunneling option.

All works fine I can ping any computer of any vpn but i have a little


I need to show you how is the netwok first:

Network A

cisco871 (VPN)

default gw

Example PC A

Network B


default gw

Example PC B

As you can see the problem is that in the network A I have a default gw

different from the cisco871 vpn.

So if I set default gw on PC A as *.254, then PC B is unalbe to ping PC A,

while PC A is always able to ping PC B.

But if I set gw of PC A as *.50 then all works fine.

I use a linux box as firewall as as default gw, I also put a

route table to route any packets coming from network

throught (cisco 871 VPN).

But that seems not to work :/ I mean if i ping from PC B any computer in the

first network none reply :/

Please help me!

thanks for any advice


2 Replies 2

Patrick Laidlaw


Set your default gateway pointing towards your router. Then set your routers default gateway as the Linux FW, Add one more route out the external interface of the router for its normal gateway point to your other router.

So Hosts would put there GW point to the router

so RTR A would have these routes

ip route

ip route external Gateway

ip route RTRB outside ip address external gateway

Then do the reverse on the other router if you have a similar setup.

Please rate any posts that are helpful.


Thank you very much for your fast reply Patrick, but i would like not to change default GW on any of my client, neither put other route on each client.

But I follow your advice and I put only these two ip route on Router A:

ip route IpRouterB FastEthernet4

ip route Tunnel0

So in any client from first network ( can ping second network ( without put as gw router A but linuxFW.

But remain the problem that from network B i can't ping host of network A is they have not the right router A as gw.

That's wierd! I would like to figure out why!

thanks a lot again patrick

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