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New Member

ATM 1483 bridging question / problem


I have a test environment setup and am running into some strange problems. I have a Cisco router setup with three ATM interfaces, two of them are going to a simulated customers with an ACL saying only packets with a certain source MAC address can go out to the customers. The third ATM interface hooks up to another router which is terminating the users. The MAC address of the router on this third interface is the one listed in the ACL. The router with three interfaces has all three on a single bridge group and all proxy-arp has been turned off on it. On the terminating router I have it setup with RBE and a /32 route for each simulated customer. If I try to go out a single PVC one customer can not talk to another. If I bind a second PVC and change the one /32 route to that then both simulated customers can talk to each other as well as the gateway router. I know I could modify the ACL on the 3 interface router and allow that to happen there but for the purpose of my simulation I have no real control of the 3 interface router. If on the terminating router I then change the /32 route to the same interface as the other and shut down the one subinterface with the PVC that has no routes to it, both simulated customers will continue to ping each other as well as the gateway from anywhere from 30 seconds to 10 minutes and then the simulated customers will stop talking to each other. I assume this must be some type of counter timing out that causes the traffic to stop, I'm just not sure what. If anyone has any ideas as to the counters or any changes to try that would make this strange setup work it would be greatly appreciated. If you feel you need any configs posted let me know.


Re: ATM 1483 bridging question / problem

Hi Steve,

Some configs may indeed help....


New Member

Re: ATM 1483 bridging question / problem

I've added copies of the relevant portions of the configs from the bridge in the middle and the gateway router. As the configs are set now simulated customer #1 and simulated customer #2 can ping the gateway as well as each other. If in the gateway router I change the one /32 route from ATM2/0.3 to ATM2/0.2 like the other /32 and even go as far as shutting down ATM2/0.3 customer #1 and customer #2 can still talk to each other, but the amount of time will vary from approx. 30 seconds to 10 minutes then it will just stop. I want to make it that customer #1 can talk to customer #2 with just a single PVC up between the bridge router and gateway router.

I know I could remove the ACL on the bridge router and my problem would go away but in the real world situation that's not an option but I do have the ability to make some changes to the bridge router.

Thanks again!

New Member

Re: ATM 1483 bridging question / problem

While I don't have a solution I might have possibly figured out what was timing out. I'm going to verify this later on. On the simulated customer computers if I do a hard code of the other computers IP address to the MAC address of the gateway router on both simulated customer computers, then they can talk to each other. I'm not sure if the packet is turning around in the testbridge router and going back out, I don't think the ACL would allow that because it wouldn't be sourced from the proper MAC. If this opens up any other ideas of what to try please let me know.