Cisco 3845 - NM-1A-T3/E3 vs NM-ATM-DS3

[thiago.dacruz]

Hello guys,

I have 2 x Cisco 3845 each one with a DS3 circuit, both running c3845-spservicesk9-mz.124-15.T3. In each of them I have one pvc provided by my carrier and I received the following info to configure:

vc-class atm ATM

  vbr-nrt 44096 44096 1

  oam-pvc manage

  oam retry 3 10 1

  encapsulation aal5mux ip

That worked fine for the first one with the NM-ATM-DS3, however, using NM-1A-T3/E3, it seems that I'm restricted up to 40700 kbps PCR/SCR:

router(config-vc-class)#vbr-nrt ?

  <64-40700>  Peak Cell Rate(PCR) in Kbps

router(config-vc-class)#vbr-nrt

I tried to look for some reference but couldn't find... Is there a way I can have a full DS3 with this card?

Regards,

[anisaini]

Hi Thiago,

This doesnt apear normal as it should have all 44mb available unless some other pvc has been configured for sharing bandwith

Please try this.

1.rather than configuring vbr under vc-class try to check directly under th pvc

int atm0

pvc x/y

vbr ?

2. if that also doesnt show the parameters correctly try the latest ios

[thiago.dacruz]

Hi Anil,

That's the only pvc I have configured. I tried to configure it directly under the pvc, got the same:

router(config-if-atm-vc)#vbr-nrt ?

  <64-40700>  Peak Cell Rate(PCR) in Kbps

router(config-if-atm-vc)#

I'll update the IOS and will come back with the results.

Regards,

[thiago.dacruz]

Hi Anil,

I've upgraded the router to the IOS c3845-adventerprisek9-mz.124-15.T12, but I'm still facing the same issue.

Regards,

[paolo bevilacqua]

A max value of 40700 is correct. That is the bandwitdh what is available to ATM, check link below. The values given when using the other module are wrong and can be disregarded.

http://sd.wareonearth.com/~phil/net/overhead/

[thiago.dacruz]

Paolo,

This is what I got on the other router with the NM-ATM-DS3:

router(config-vc-class)#vbr-nrt ?

  <64-44209>  Peak Cell Rate(PCR) in Kbps

router(config-vc-class)#vbr-nrt

I believe that 40700 would be the max throughput I will have, however the line rate for that should be 44700, no?

Regards,

[paolo bevilacqua]

The bit rates command is about bandwidth available to ATM, including cell overhead.

Physical line rate is something else.

Read the document and you will understand.

[thiago.dacruz]

Paolo,

I understood it, but then when Cisco allows me to configure up to 44209 they are incorrectly doing it?

Regards,

[paolo bevilacqua]

Again: Old product allows incorrect config due to a bug. New product behaves correctly.

[Nitin Verma]

Hi Cruz,

You need to check & change the Framing from Main New (NM-1A-T3/E3) Interface.. from your existing framing type cbitplcp to cbitadm to achieve the desired line-rate of DS3...

Let us know once you are done...