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Natting Problem

mijadhav
Level 1
Level 1

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

address mapped to it ( 10.174.44.82/28 and 10.174.44.83/28 ) anda

virtual IP address ( 10.174.44.81/28) . 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 :- 10.30.247.17/28

and 10.174.44.94/28 .

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

of 10.30.250.210/30 .

Our ethernet port has a following NAT command

ip nat inside source static 10.174.44.81 10.30.247.19

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 10.174.44.82 10.30.247.19

we are able to ping the outside world.

Observation:

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

10.174.44.94/28

4. With source as 10.30.247.17 the ping is successfull.

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

is required please let us know.

1 Reply 1

mark-obrien
Level 4
Level 4

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 10.174.44.94 as the source address, and succeeding with 10.30.247.17, the peer router probably does not have a route to 10.174.44.80/28.

HTH

Mark