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Frame Problem

Im currently employing a 1720 cisco router for our frame relay router and we currently have 25 (sub-interface) frame relay links connected.

Recently we have noticed that some of our sites goes down and upon checking the links we found out that the PVC's has been deleted. We log a problem with our Telco and they said that their link is OK.

Can somebody tell me how many sub-interface we can create on a single serial interface

I did a debug at one of the site which went down and below is the result. Also shown here is the version of the router Im currently employing at my HQ

ay_Office#debug frame-relay lmi interface serial0

Frame Relay LMI debugging is on

Displaying lmi data from interface Serial0 only


00:03:10: Serial0(out): StEnq, myseq 7, yourseen 28, DTE up

00:03:10: datagramstart = 0x261CE78, datagramsize = 14

00:03:10: FR encap = 0x00010308

00:03:10: 00 75 95 01 01 01 03 02 07 1C


00:03:10: Serial0(in): Status, myseq 7

00:03:10: RT IE 1, length 1, type 1

00:03:10: KA IE 3, length 2, yourseq 29, myseq 7

00:03:20: Serial0(out): StEnq, myseq 8, yourseen 29, DTE up

00:03:20: datagramstart = 0x261CE78, datagramsize = 14

00:03:20: FR encap = 0x00010308

00:03:20: 00 75 95 01 01 00 03 02 08 1D


00:03:20: Serial0(in): Status, myseq 8

00:03:20: RT IE 1, length 1, type 0

00:03:20: KA IE 3, length 2, yourseq 30, myseq 8

ay_Office#sho frame-relay pvc

PVC Statistics for interface Serial0 (Frame Relay DTE)


input pkts 0 output pkts 1 in bytes 0

out bytes 294 dropped pkts 0 in FECN pkts 0

in BECN pkts 0 out FECN pkts 0 out BECN pkts 0

in DE pkts 0 out DE pkts 0

out bcast pkts 1 out bcast bytes 294

pvc create time 00:03:34, last time pvc status changed 00:01:29

ITC_FR_Host#sho ver

Cisco Internetwork Operating System Software

IOS (tm) C1700 Software (C1700-Y-M), Version 12.1(4), RELEASE SOFTWARE (fc1)

Copyright (c) 1986-2000 by cisco Systems, Inc.

Compiled Wed 30-Aug-00 08:36 by cmong

Image text-base: 0x80008088, data-base: 0x805D8590

ROM: System Bootstrap, Version 12.0(3)T, RELEASE SOFTWARE (fc1)

ITC_FR_Host uptime is 14 weeks, 6 days, 18 hours, 12 minutes

System returned to ROM by power-on

System image file is "flash:c1700-y-mz.121-4.bin"

cisco 1720 (MPC860) processor (revision 0x501) with 12288K/4096K bytes of memor.

Processor board ID JAD04340N48 (3727872350), with hardware revision 0000

M860 processor: part number 0, mask 32

Bridging software.

X.25 software, Version 3.0.0.

1 FastEthernet/IEEE 802.3 interface(s)

1 Serial(sync/async) network interface(s)

32K bytes of non-volatile configuration memory.

4096K bytes of processor board System flash (Read/Write)

Configuration register is 0x2102

  • Other Network Infrastructure Subjects

Re: Frame Problem

You can configure 300 subinterfaces on this router (as per IDB limitations )

As for your deleted PVC status. please ensure you do not have "no keepalives" on the subinterfaces. This can also indicate that the provider does not have this DLCI on the Frame Switch for some reason.

Check out this link with the status fields explained for you to help you troubleshoot this further.

Hope this helps you,


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