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New Member

Loss of connectivity/ATM bundle

Hi all,

I have a problem with ATM that my service provider and we say that it shuold not be happening.

We have 8 international sites connected through the same carrier.

The network topology is about the same at each site, as are the router configs.

A couple of those places are experiencing the problem I´m trying to solve.

Even though we have at least two E1´s bundled in one ATM IMA group, when one of the E1´s goes down, we lose connectivity to that site until the controller is up again. It doesn´t matter wich controller it is. At the other sites, when one controller goes down, we don´t lose connectivity. The routers, configs and the carrier are the same for all sites. Even the routing is the same

Can someone point me in the right direction, please?

Thanks to all for your help.

Eduardo.

CISCO IOS: c3725-jk9s-mz.123-16.bin

ROUTER CONFIG:

!

controller E1 0/0

mode atm aim 1

!

controller E1 0/1

mode atm aim 1

!

interface ATM0/0

description GM2413 to Lucent ATM network ima-group 0 4/1

bandwidth 2048

no ip address

load-interval 30

scrambling-payload

ima-group 0

no atm ilmi-keepalive

no clns route-cache

!

interface ATM0/1

bandwidth 2048

no ip address

load-interval 30

scrambling-payload

ima-group 0

no atm ilmi-keepalive

no clns route-cache

!

interface ATM0/IMA0

bandwidth 4096

no ip address

load-interval 30

ima differential-delay-maximum 200

no atm ilmi-keepalive

no clns route-cache

!

interface ATM0/IMA0.1 point-to-point

description 2 E1s ref. NSR GM2413 to Lucent ATM network ima-group 0 4/1

bandwidth 4096

ip address 162.xx.yyy.zzz 255.255.255.252

pvc 6/150

!

7 REPLIES

Re: Loss of connectivity/ATM bundle

Can you post the output of 'show ima interface ATM0/IMA0 detail'

--Sundar

New Member

Re: Loss of connectivity/ATM bundle

Sure. Thanks for your response:

ARGENTINA1B_AIRES#sh ima inter atm0/ima0 det

Interface ATM0/IMA0 is up

Group index is 23

Ne state is operational, failure status is noFailure

IMA Group Current Configuration:

Tx/Rx minimum required links 1/1

Maximum allowed diff delay is 200ms, Tx frame length 128

Ne Tx clock mode CTC, configured timing reference link ATM0/0

Test pattern procedure is disabled

Detailed group Information:

Ne IMA version in operation IMA Version 1.1

Fe IMA version in operation IMA Version 1.1

Tx/Rx Ima_id 0x21/0x1

Ne state operational Fe state operational

Ne symmetry symmetricOperation Fe symmetry symmetricOperation

Number of Tx/Rx configured links 2/2

Number of Tx/Rx active links 2/2

Ne clock mode ctc, Tx frame length 128

Fe clock mode ctc, Rx frame length 128

Tx/Rx timing reference link 0/0

Maximum observed DCB depth 4 cells, Maximum DCB depth 2 cells

Maximum observed diff delay 0ms, Maximum diff delay 0ms

Least delayed link 1, Most delayed link 0

GTSM last changed 00:00:13 CST Mon Mar 1 1993

IMA Group Total Counters (time elapsed 2176 seconds):

1267277 Tx cells, 1295170 Rx cells

24 Ne Failures, 13 Fe Failures, 434 Unavail Secs

Detailed IMA link Information:

Interface ATM0/0 is up

ifIndex 9, Group Index 23, link exists and is operational

Tx/Rx Lid 0/0

Ne Tx/Rx state active/active

Fe Tx/Rx state active/active

Ne Rx failure status is noFailure

Fe Rx failure status is noFailure

Tx/Rx test pattern 0x0/0xFF

IMA Link Counters

0 Ima Violations, 0 Oif Anomalies

102 Ne Severely Err Secs, 335 Fe Severely Err Secs

1 Ne Unavail Secs, 1 Fe Unavail Secs

2 Ne Tx Unusable Secs, 94 Ne Rx Unusable Secs

47 Fe Tx Unusable Secs, 336 Fe Rx Unusable Secs

0 Ne Tx Failures, 5 Ne Rx Failures

6 Fe Tx Failures, 290 Fe Rx Failures

68377 Tx stuff events, 68090 Rx stuff events

Interface ATM0/1 is up

ifIndex 14, Group Index 23, link exists and is operational

Tx/Rx Lid 1/1

Ne Tx/Rx state active/active

Fe Tx/Rx state active/active

Ne Rx failure status is noFailure

Fe Rx failure status is noFailure

Tx/Rx test pattern 0x0/0xFF

IMA Link Counters

0 Ima Violations, 0 Oif Anomalies

6980 Ne Severely Err Secs, 6982 Fe Severely Err Secs

1 Ne Unavail Secs, 1 Fe Unavail Secs

0 Ne Tx Unusable Secs, 6973 Ne Rx Unusable Secs

6468 Fe Tx Unusable Secs, 6991 Fe Rx Unusable Secs

0 Ne Tx Failures, 3 Ne Rx Failures

7 Fe Tx Failures, 501 Fe Rx Failures

39842 Tx stuff events, 24357 Rx stuff events

Re: Loss of connectivity/ATM bundle

Config looks OK.

How do you know both links didn't go down when you couldn't get to the device. There are errors on both ATM interfaces. What was the status of the PVC on the other end of the connection?

--Sundar

New Member

Re: Loss of connectivity/ATM bundle

The site has another carrier and we had the oprtunity to connect through them while running a series of tests. The router log only shows that one link goes down, but not the other. The errors are due to an interface converter that will be replaced in a few days. The pvc on the other side is up. They do not see any problem as well.

Re: Loss of connectivity/ATM bundle

The best way to troubleshoot this is to connect to the router via out-of-band connection, disable one ATM interface and run debugs. With no out-of-band access you would have go by what carrier tells you is the status of the 2nd link and mightn't be that helpful.

Troubleshoot IMA using the following document.

http://www.cisco.com/en/US/partner/tech/tk39/tk356/technologies_tech_note09186a0080093d52.shtml

Post any specific questions to the forum.

--Sundar

New Member

Re: Loss of connectivity/ATM bundle

Thanks! I appreciate your help. As soon as we run some tests, I´ll keep you posted.

New Member

Re: Loss of connectivity/ATM bundle

It seems that the problem was a misconfigured pvc

in our service provider network. The pvc min bw was configured for about 4MB, so when one E1 went down, the remaining bw (2MB) was not enough to support the pvc, so the pvc went down. Our ISP configured the min

bw to 1886800 and that did it.

Thanks for your interest and your comments.

Regards,

Eduardo

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