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additional hop in layer2 connection

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christian maier

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Jun 20, 2009, 5:54:52 AM6/20/09
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Hi!

I have a very strange problem with 2 cisco routers connected over
layer 2 cisco switches (catalyst 6500).
Both routers are connected over a VLAN and they see each others
IP- and MAC-address in the arp cache (they can ping each other).
But when I traceroute from one to the other, I see a an additional hop
* * * before I see the ip-address of the other end (this happens on
both routers). Also when I mirror the switchports where the routers
are connected, I only see traceroute udp packets with TTL=2.
I do not see the TTL=1 packets, because of this strange internal hop.
This causes big problems with HSRP, because HSRP has TTL=1.
And this first hop is this internal hop, so HSRP packets
never come to the switch (and not to the other router).

Any ideas?

Thanks.

Christian

Christian Maier

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Jul 5, 2009, 12:05:57 AM7/5/09
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It was the IPS (Intrusion Prevention System)!
This blocked UDP with TTL=1.

"christian maier" <christ...@yahoo.de> schrieb im Newsbeitrag
news:12454916...@news.aic.at...

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