The Autosense feature should be taken with a grain of salt. If you need a specific connection to work, you should set the speed and duplex manually.
One of the first thing I became aware of many years ago is that most "auto" features are spastic at best ON ANY EQUIPMENT. Not just Cisco! I have had strange problems when the equipment rebooted later on. If you set it when you configure the interface you will save a lot of grief. I also recommend this action for client stations. To eliminate problems specify in your Policy and Procedures manual that "Autosense" is not to be used. Dom Marino ""Ole Drews Jensen"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > After a fun evening last night, I have decided not to trust the autosensing > on ethernet interfaces anymore. > > I was at a branch office where the users could not access the corporate > network. The router, a 1720 setup as a bridge with the same IP address for > the FastEthernet as the Serial subinterface, both configured for > bridge-group 1. It was connected to a 2620 at the corporate office via a > Fractional Frame Relay connection. > > I changed the switch out with an old spare hub I had lying around, and > connected only one workstation from the local network. After starting the > router up, I could ping the local workstation, and I could ping devices on > the corporate network, so both my FastEthernet and Serial interfaces were > working fine. However, I could not ping anything on the corporate network > from my workstation, nor could I from a telnet connection to my corporate > router ping the workstation, so traffic was not being passed through between > the interfaces. > > That looked like a typical routing problem, but the only problem was that I > was not routing, I was bridging, so ????? > > I did a "show bridge 1 group" and saw that the FastEthernet was in a > blocking state by the spanning tree, so something was wrong here. I cleared > the arp table on the router and on all other routers and switches. I tried > to assign a different mac address to the FE interface. I tried a different > workstation. No matter what I did, it kept being in a blocking state. > > I went in and did a "bridge-group 1 spanning-disabled" on the interface, and > it changed to forwarding state, but I could still not pass traffic through. > > This is when I called TAC, but after I guided them through to a telnet > connection to my routers, they decided after three hours that something > weird was going on with the router, and they did an RMA for a replacement > unit. > > However, I decided to continue my troubleshooting, because I hate to give > up. I reconfigured everything, I tried to create a bridge-group 2 instead, I > forced it into IP routing, and back off it again, but no matter what, it > kept going into blocking mode (I had removed the spanning-disabled command > again at that time). > > That's when it hit me to try and force the speed on the interface. It was in > AUTO, and my switch had been auto 10/100, but my hub was only 10. I changed > it from auto to 10 and power cycled the router. PLING!!! Now it started up > and after the listening and learning, it went in forwarding state, and I > could now ping through my router, and I could connect my workstation to the > corporate network. > > What makes this strange is that I can apparently use my FastEthernet > interface from the router even though the speed is wrong, but the STP see's > this and blocks the interface for switched traffic. WEIRD!!!!! > > Read the entire case study here: > > http://www.RouterChief.com/CaseStudies/1.htm > > Ole > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Ole Drews Jensen > Systems Network Manager > CCNP, MCSE, MCP+I > RWR Enterprises, Inc. > [EMAIL PROTECTED] > http://www.RouterChief.com > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > NEED A JOB ??? > http://www.oledrews.com/job > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=30476&t=30446 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
