Cisco Systems additional hop in layer2 connection

Bookmark this page:  YahooMyWeb Yahoo!  Google Google  Windows Live Favorites Windows Live  del.icio.us del.icio.us  digg digg  Add to Netscape Netscape
Subject Author Date
additional hop in layer2 connection christian maier 06-20-09
Posted by christian maier on June 20, 2009, 5:54 am
Please log in for more thread options
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

Posted by Christian Maier on July 5, 2009, 12:05 am
Please log in for more thread options
It was the IPS (Intrusion Prevention System)!
This blocked UDP with TTL=1.



Similar ThreadsPosted
additional hop in layer2 connection June 20, 2009, 5:54 am
QoS for layer2? August 7, 2006, 10:58 am
VLAN over Layer2/3 Help... August 8, 2005, 9:08 am
Adding an additional route to a PIX 525? March 6, 2007, 8:32 am
2821 - additional ports March 5, 2007, 9:03 am
additional web-auth authorization August 22, 2010, 9:22 am
Managing ASA55xx with additional software August 8, 2006, 11:28 am
Extending Cisco 2612 with additional FastEthernet August 14, 2005, 2:04 pm
Adding additional routes to a VPN client (PIX515E and Cisco client) October 28, 2006, 8:17 pm
Failover and Load balancing with 1 Cable connection and one T1 connection on Cisco 2801 router November 13, 2006, 2:23 pm
VPN connection issue; no data passing after connection August 22, 2007, 11:37 am
E1 connection November 25, 2005, 7:13 pm
FXO to FXO connection December 18, 2006, 6:51 am
PIX 501 and Connection to Company VPN. July 24, 2005, 9:07 am
Connection reset ! September 1, 2005, 5:53 pm
Latest PostsForumRSS
NEWS: Android Mobile Web Market Share Steadily Rising Wireless Networking
c3560 port configuration Cisco Systems
A Strong Password Isn't the Strongest Security [telecom] General Telecommunications Forum
Control Hot Water Circ Pump With X10? General Home Automation
Telecom Hardware Cisco Certification
PROMO * MVTS II v.1.3.1-50 to 1.4.0-50 - Professional Insta... Voice-Over-IP
USB _to_ RJ45 (not from) connection Ethernet LAN
FAQ: Maximizing cable modem or DSL speed Cable Modems
CASH FOR CISCO - I BUY USED AND NEW EQUIPMENT & LOTS MOR... Telecom Technical
FAQ: Maximizing cable modem or DSL speed Digital Subscriber Line
How to set up Meridian 1 to "provide clock" to a C... Nortel Networks
New Discovery about WDM LAN and Telecom Cabling
Control Hot Water Circ Pump With X10? Home Automation
Text file to automate restoring a dropped VPN connection. Virtual Private Networks
Home Theater Installation Home Theater
Re: The Turkic Languages in a Nutshell Fiber Optics
sip Video Conferencing
Residential Cabling Guide Home Cabling Guide

Finally, an instantly downloadable book that saves you thousands in home improvement dollars! Enjoy living in 21st century technology-advanced home while increasing its selling value and competitive advantage on the real estate market. Whether your cabling is for home office or high-tech leisure, you can wire your home yourself or learn "wirish" to speak with your cabling contractors in their language!

Click Here to learn more