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Natting Problem

We have a Microsoft cluster server with 2 nodes each having a IP

address mapped to it ( and ) anda

virtual IP address ( . This server is connected a

Cisco 2507 router's ethernet port. WE have a primary and secondary IP

address assigned to the ethernet port as follows :-

and .

This router's serial 0 is connected to external network with IP range

of .

Our ethernet port has a following NAT command

ip nat inside source static

ip nat inside

serial 0

ip nat outside

Problem: we are able to ping the outside world from the router however

ping fails when we ping the outside world from the server.

When we change the NAT statement as follows

ip nat inside source static

we are able to ping the outside world.


1. When we use either of the node IP's to ping it works

2. with natting of virtual IP of the cluster , Ping fails

3. Extended ping from the router fails when source address is taken as

4. With source as the ping is successfull.

Any help on the issues will be highly appreciated, If any other info

is required please let us know.


Re: Natting Problem

It sounds like, when one of your servers pings, it uses the address of its physical interface as the source address, instead of using the the cluster address. As for pings failing when using as the source address, and succeeding with, the peer router probably does not have a route to



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