At 08:25 PM 10/28/01, Tribavan Raina wrote: >Hi.. > >When we give no keepalive command on ethernet or fast ethernet ,the port and >line protocol come up but when we do the same thing for serial port why >doesnt it work.
It should work if you turn keepalive off on both ends of the serial link. On Ethernet, the router sends a keepalive to itself. It looks like this: Ethernet Header Destination: 00:00:0C:05:3E:80 Source: 00:00:0C:05:3E:80 Protocol Type:0x9000 Packet Data: 46 bytes (all zeros) If the router can send and receive these, then it's happy. If you tell it not to check to see if it can send and receive these (no keepalive), it's happy too. On serial links, the router sends a keepalive to the other end of the link and expects a reply. I don't have a serial sniffer, but here's what the debug looks like: charlotte#debug serial int Serial network interface debugging is on charlotte# Serial0: HDLC myseq 2, mineseen 2, yourseen 5, line up Serial0: HDLC myseq 3, mineseen 3, yourseen 6, line up Serial0: HDLC myseq 4, mineseen 4, yourseen 7, line up Serial0: HDLC myseq 5, mineseen 5, yourseen 8, line up Serial0: HDLC myseq 6, mineseen 6, yourseen 9, line up Serial0: HDLC myseq 7, mineseen 7, yourseen 10, line up The router keeps track of its own sequence number (myseq), the ACKs for its sequence numbers coming from the other side (mineseen), and the sequence numbers coming from the other side (yourseen). The router increments its sequence number by one every 10 seconds, when it sends its next keepalive. It expects the ACKs from the other side to keep pace. If they don't, it declares the link down. The other side does the same thing. But if you turn off keepalive on both ends of an HDLC link, the link stays up. I haven't tried it with other encapsulations such as Frame Relay. Priscilla >May be it is a silly question. ________________________ Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=24539&t=24446 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
