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Pings lose TTL going to radios

westmanm
Level 1
Level 1

Here is the goofy situation I found last night. I have installed a very large WLAN network for a local government. Most of the network is based on the BR350s, but there are some BR340 segments that live on their own. The radios are all in the same subnet, but have routers behind them to seperate the network into managable segments.

When I connected my laptop into a switch connected to a repeater and pinged another radio I saw that the TTL on the ping was either 64 or 127 depending on how many wireless hops away the radio was. If I pinged a managment workstation that's on the same subnet as my laptop and the radios I got the expected 255 TTL.

So, why is the TTL getting reduced pinging to a radio, but not to a workstation? The customer is confused, and so am I.

-Mike

4 Replies 4

westmanm
Level 1
Level 1

Anyone?

-Mike

how many switch ports and wireless interfaces does this ping go through

Every device that forwards the packet will reduce its ttl

jacky.reinbold
Level 1
Level 1

Hi Mike,

I experienced a similar problem on a point to point link after upgrading from version 11.07 to 12.2.T1 and I was amazed about seeing the radio ports as primary ports configured and have changed it to ethernet side.

Like you the bridges were on the same subnet and behind the non-root bridges a Win 2000 PC with 2 NICs was directly connected as a router.

It was impossible to ping the non-root bridge from the root side network.

But the traffic was going through.

I could not find any solution and have opened recently a case on the TAC.

Did you know any solution since you wrote this issue ??

Jacky

I don't know of any solution on this issue, and I'm afraid that there is a loop forming somewhere in this wireless network. I don't know of two many other people that have MANs of fifty BR350 radios and I'm wondering if something is going on here that Cisco didn't plan on.

-Mike

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