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Cisco 2811 router serial interface ping windows hosts can't ping unix hosts

I am currently running a Cisco 4000, site A and a Cisco 3745 Site B, with a serial interface connected via a T1. At the 4000 site I have 200 windows hosts and 2 Unix (Tru64) hosts. With the 4000 in place I can ping all the hosts from site B including the Unix hosts, as well as telnet to the Unix hosts. I replaced the 4000 with a new 2811 router, and I can ping and get access to all the Windows hosts, but can not ping the Unix hosts. It is not a "routing table" issue as I get access to the Windows hosts on the same subnet, I suspect it may be the 2811's security, and it does not like the older TCP stack on the Tru64 unix systems. The configuration works, as the Windows TCP protocol works. When I put the 4000 back, I can access the Unix, does anyone have similar problems? I plan to do some tests, I will check to see if it a configuration on the Ethernet or Serial interface on the 2811, or run the security wizard to see what TCP stuff it blocks.


Re: Cisco 2811 router serial interface ping windows hosts can't


If you could paste the sh run (by taking off all the confidential info), we would be more than happy to help you out.


Wilson Samuel


Re: Cisco 2811 router serial interface ping windows hosts can't

I would check and see if you have proxy arp running on the router. This used to be on by default. There are some recomendation to disable this and if you ran the security wizard it more than likely turned it off. Your unix machines may be misconfigured or may not understand the concept of default gateway. It may have just issued arp for any unkown address and the router would be more than happy to respond that it would take the traffic when it has a route in the table.

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