11-26-2012 05:28 AM - edited 03-07-2019 10:14 AM
Hello,
i try to ping an unreachable host to generate an icmp unreachable message on our 3750. I also tested it with an 6500. It didn´t work.
ip unreachables on the Layer3 Interface is enabled
Then I tested it with a basic Router and it worked fine. On Nexus 7k it worked also.
Does everybody know if an Layer3 Switch generally sends ICMP Unreachables ?
To me it should because of:
sh ip interface vlan 40
ICMP unreachables are always sent
Thanks
Philip
11-26-2012 05:59 AM
Do you have any mls rate-limiter, control-plane policing, acl or qos blocking ICMP un-reachable messages
Thank you
Raju
11-26-2012 06:30 AM
No nothing of that
Can i verify with an debug command that my Layer3 Switch sends out the packets or not ?
I sniffed at the network card of my computer with wireshark and there were no icmp reply
11-26-2012 06:39 AM
You can do " deb ip icmp" and check if you are sending unreachables
Thank you
Raju
11-26-2012 06:54 AM
Hi,
if you want to see debugs for transit traffic you'll have to disable ip cef for the interfaces with no ip route-cache cef command
Regards.
Alain
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11-26-2012 07:43 AM
i made an debug on the switch and there is no output of any unreachable packets.
in the debug of the router i thought every unreachable message.
Is that a correct behavior ?
11-26-2012 07:54 AM
What is the IP you are trying to ping?
Can you collect below output from 6500
1. Show ip cef
2. Show ip traffic
Thank you
Raju
11-26-2012 08:13 AM
i did it on an 3750G
show ip cef 192.168.251.200
show ip traffic
ICMP statistics:
Sent: 0 redirects, 0 unreachable, 15 echo, 73360 echo reply
0 mask requests, 0 mask replies, 0 quench, 0 timestamp
0 info reply, 0 time exceeded, 0 parameter problem
0 irdp solicitations, 0 irdp advertisements
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