You need to have clocking internal on one end and line (default) on the other. atm clock INTERNAL I don't have Caslow handy so don't know if the above is included in the config. Here's a working config between two 7500s. They are running 11.3 First end: interface ATM6/0 description Location AnyCo_North. Always node 4. no ip address atm clock INTERNAL ! interface ATM6/0.1 multipoint description pvc to Data Center via fiber ip address xxx.yyy.7.250 255.255.255.252 secondary ip address 10.18.35.4 255.255.255.0 atm pvc 1 0 35 aal5snap map-group TGN appletalk cable-range 35-35 35.4 appletalk zone ATM map-list TGN ip 10.18.35.1 atm-vc 1 broadcast appletalk 35.1 atm-vc 1 broadcast ip xxx.yyy.7.249 atm-vc 1 broadcast Other end: interface ATM12/0 description Location AnyCo. Always node 1. no ip address ! interface ATM12/0.1 multipoint description pvc to AnyCo_North ip address xxx.yyy.7.249 255.255.255.252 secondary ip address 10.18.35.1 255.255.255.0 atm pvc 1 0 35 aal5snap map-group TGE appletalk cable-range 35-35 35.1 appletalk zone ATM map-list TGE ip 10.18.35.4 atm-vc 1 broadcast appletalk 35.4 atm-vc 1 broadcast ip xxx.yyy.7.250 atm-vc 1 broadcast > -----Original Message----- > From: Tom Keough [mailto:[EMAIL PROTECTED]] > Sent: Saturday, September 15, 2001 2:06 PM > To: [EMAIL PROTECTED] > Subject: Problem connecting 2 routers w/ATM OC3 int back to back > [7:20061] > > > Hello groupstudy, > The problem is that when I configure and no shut the > interfaces they just > bounce between up and down every few seconds. I can put up a "loopback > diagnostic" and ping each interface ok. I have connected a > 3640 and a 2600 > each with an ATM OC3 card back to back. I suspect I have not > installed the > two multimode fiber cables properly. I have searched CCO but > can't find > instructions for cabling the back to back configuration. I am > using Caslow's > book for the ATM configuration. > > I just read in the ATM section of the All-In-One CCIE Lab > Study Guide about > using one fiber cable for the back to back config vs. two > cables to a switch > but which cable to which jack?? I won't have access to my lab > again until > Monday or I'd be cable swapping right now. > > If anyone has any info on this I would greatly appreciate hearing from > you... > TIA, > Tom > > -- > > Tom Keough, CCNP MCSE > CCIE Candidate > [EMAIL PROTECTED] > Report misconduct > and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=20076&t=20076 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]