Bad Hop Count

Rudy.Lim · ‎01-28-2002

Hello,

Anyone who can give me solution/s on how to reduce or make the bad hop count to zero? I also get 4 format errors and some encapsulation failures. The network seems working fine but I'd like to know how critical these error messages and how to solve it?

The router is 3640 and these messages came to monitor the ip traffic. Thanks in advance.

Rudy

j-lau · ‎02-01-2002

What is the specific error you're receiving? And how are you seeing the errors? (Syslog? SNMP? Are you issuing a command? On the console?)

Rudy.Lim · ‎02-01-2002

Thanks for the reply. When I ran sh ip traffic, the statistics report showed that my 3640 router has gathered a total of 2,385 bad hop count. This one keeps on increasing but very slowly.

I also have a fixed 4 format errors.

j-lau · ‎02-01-2002

Well, with regard to the "bad hop count" error, I'll give the technical (and totally unhelpful) answer:

The router increments that counter when it must discard a packet because the packet's TTL (time-to-live) counter has reached (decremented) zero.

To gain some insight into how "big" of a problem it is, you need to do some math. How many packets are being discard vs how many were received in total by the router?

On my network, looking at a few routers, the number of "bad hop" discard packets to the total number is less then .5% (.005!) of the total number of IP packets received. I'm not too worried. You have to decide for yourself and your network.

Now, that said, there are other things which can contribute to Bad Hop counts incrementing which you might consider investigating on your network

1. Are you doing multi-casting?

2. Problems or issues with routing? Routing loops? Null routes? (Multiple routing protocols running?)

3. Network management tools running discovery sweeps?

4. Network path discovery tools running?

5. Do you have active security tools running? (Or are network probes being done?)

Rudy.Lim · ‎02-04-2002

Yes, I understand the use of hop count. To naswer your questions, we do not use multi-casting, we use only RIPv2 as routing protocol (simple network), no management or network path tools running, CDP is disabled, no network probes being done.

Rudy.Lim · ‎02-04-2002

Thanks for the info. Yes, I understand the use of hop count. To answer your questions, we do not use multi-casting, we use only RIPv2 as routing protocol (simple network), no management or network path tools running, CDP is disabled, no network probes being done.

Is there such thing as maximum acceptable percentage of packets discarded vs. packets received?