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Serial Interfaces' Dependencies

salau
Level 1
Level 1

Hello NetPros,

As anyone come across issues where a serial connection (say s0/1) going down, tend to bring down another serial connection.

The scenerio is that, say RouterA has 2 serial interfaces s0/1 and s0/2. s0/1 is a ppp connection via a V100 satellite link, and s0/2 is a frame-relay connection with several subinterfaces ... Say s0/2.1,s0/2.2,s0/2.3,s0/2.4,s0/2.5 etc.

The problem is, whenever s0/1 goes down, it takes s0/2 main interface down with it, which in turn take down all the sub-interfaces with it.

Is there any reason why this should be, I'm guessing hardware related fault on the Hub Router, or a software bug ... Anyone come across this, please let me know.

!

interface Serial0/1

bandwidth 512

ip address A.B.C.D W.X.Y.Z

encapsulation ppp

ip route-cache flow

no fair-queue

no cdp enable

!

!

interface Serial0/2

bandwidth 2048

no ip address

encapsulation frame-relay IETF

ip route-cache flow

no ip route-cache cef

frame-relay traffic-shaping

frame-relay lmi-type ansi

frame-relay interface-queue priority 10 20 30 40

!

interface Serial0/2.1 point-to-point

bandwidth 128

ip address B.B.C.D W.X.Y.Z

no cdp enable

frame-relay interface-dlci 1

class 64k_cir_128k_bc

!

interface Serial0/2.2 point-to-point

bandwidth 128

ip address B.B.C.E W.X.Y.Z

no cdp enable

frame-relay interface-dlci 2

class 64k_cir_128k_bc

!

interface Serial0/2.3 point-to-point

bandwidth 128

ip address B.B.C.F W.X.Y.Z

no cdp enable

frame-relay interface-dlci 3

class 64k_cir_128k_bc

!

!

interface Serial0/2.4 point-to-point

bandwidth 128

ip address B.B.C.G W.X.Y.Z

no cdp enable

frame-relay interface-dlci 4

class 64k_cir_128k_bc

!

interface Serial0/2.5 point-to-point

bandwidth 128

ip address B.B.C.H W.X.Y.Z

shutdown

no cdp enable

frame-relay interface-dlci 5

class 64k_cir_128k_bc

!

interface Serial0/2.6 point-to-point

bandwidth 256

ip address B.B.C.I W.X.Y.Z

no cdp enable

frame-relay interface-dlci 6

class 128k_cir_256k_bc

!

interface Serial0/2.7 point-to-point

bandwidth 128

ip address B.B.C.J W.X.Y.Z no cdp enable

frame-relay de-group 1 7

frame-relay interface-dlci 7 IETF

class 64k_cir_128k_bc_inc_2_voice

vofr data 4 call-control 5

frame-relay payload-compression FRF9 stac

!

interface Serial0/2.8 point-to-point

bandwidth 32

no cdp enable

frame-relay interface-dlci 8

class 56k_cir_7k_bc_2_voice

vofr data 5 call-control 4

!

Many Thanks

Yemi Salau

3 Replies 3

Richard Burts
Hall of Fame
Hall of Fame

Yemi

Some additional information would be helpful. What platform is this running on? Are both serial interfaces on the same card (from the interface addressing I would assume so)? What kind of card is it? Does it happen all the time that if serial0/1 goes down that serial0/2 also goes down or is it sometimes?

HTH

Rick

HTH

Rick

Thanks Rick,

Here is a sh ver:

Cisco IOS Software, 3700 Software (C3745-JSX-M), Version 12.3(7)T, RELEASE SOFTW

ARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2004 by Cisco Systems, Inc.

Compiled Sat 21-Feb-04 05:53 by eaarmas

ROM: System Bootstrap, Version 12.2(8r)T2, RELEASE SOFTWARE (fc1)

RouterA uptime is 6 weeks, 17 hours, 32 minutes

System returned to ROM by reload at 19:32:39 bst Tue Oct 16 2007

System restarted at 19:35:03 bst Tue Oct 16 2007

System image file is "flash:c3745-jsx-mz.123-7.T.bin"

Cisco 3745 (R7000) processor (revision 2.0) with 116736K/14336K bytes of memory.

Processor board ID JHY0753K01M

R7000 CPU at 350MHz, Implementation 39, Rev 3.3, 256KB L2, 2048KB L3 Cache

2 FastEthernet interfaces

6 Serial(sync/async) interfaces

1 ATM interface

8 Voice FXO interfaces

DRAM configuration is 64 bits wide with parity disabled.

151K bytes of NVRAM.

31744K bytes of ATA System CompactFlash (Read/Write)

Configuration register is 0x2102

***************************************************

1. Yes, Both Serial interfaces are on the same module. Hardware is GT96K Serial WIC

2. This happen all the time if s0/1 goes down due to various reasons like weather(since it's a satellite V100 link), then s0/2 will go down as well.

Cheers

Yemi

Yemi

Thank you for the additional information. I find it very unusual that the second interface always goes down if the first one goes down, especially for reasons such as weather affecting satellite. If serial0/2 goes down does it take down serial0/1?

I would be inclined to open a case with TAC if there is a maintenance contract on this router. If a TAC case is not possible I would try upgrading the software on the possibility that it might be a software issue.

HTH

Rick

HTH

Rick
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