PRI Problem on Cisco 3640 router (TEI_ASSIGNED)

[hucuncu]

I have a Cisco 3640 router with 4-port Channelized E1 inserted. One of these E1 ports is used as an ISDN PRI connection to Telco for ISDN backup purposes. Branch offices, who are able to dial using ISDN BRI interfaces, try to connect to E1 PRI port.

However, something goes wrong and I was unable to dial out (or connect to) anywhere from my router. Besides, nowhere is able to dial in. The following configuration does not work on the interface:

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

!

isdn switch-type primary-net5

!

controller E1 3/1

framing NO-CRC4

pri-group timeslots 1-31

description Pri to Bri

!

interface Serial3/1:15

bandwidth 64

no ip address

encapsulation ppp

dialer pool-member 101

dialer pool-member 1

dialer pool-member 25

isdn switch-type primary-net5

ppp authentication chap

ppp multilink

!

!

interface Dialer25

description test

bandwidth 60

ip unnumbered Loopback0

encapsulation ppp

dialer pool 25

dialer load-threshold 200 either

dialer-group 1

no snmp trap link-status

pulse-time 0

ppp authentication chap

ppp multilink

!

dialer-list 1 protocol ip permit

!

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

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

Router#sh isdn status

Global ISDN Switchtype = primary-net5

ISDN Serial3/1:15 interface

dsl 0, interface ISDN Switchtype = primary-net5

Layer 1 Status:

ACTIVE

Layer 2 Status:

TEI = 0, Ces = 1, SAPI = 0, State = TEI_ASSIGNED

TEI = 60, Ces = 1, SAPI = 30, State = TEI_ASSIGNED

Layer 3 Status:

0 Active Layer 3 Call(s)

Active dsl 0 CCBs = 0

The Free Channel Mask: 0xFFFF7FFF

Total Allocated ISDN CCBs = 0

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

1- Is it possible to see two distinc TEI under Layer 2 status item? Shouldn't it be single TEI?

2- Although I have tried various commands under 'Serial 3/1:15', nothing changed? What do you suggest next?

Thanks for all..

Onur

[tepatel]

No..TEI should be 0 for T1/E1 PRI unless some other services are subscribed.

Looks to me that the E1 line is not in sync with switch on layer 2. So you need to make sure that "sh controller E1" reports clean stats. Here are some urls which will help you to troubleshoot layer 2 issues

http://www.cisco.com/warp/public/116/E1_pri.html

It also has some more useful links under "related docs" on the bottom of that page.

[makchitale]

"debug isdn q921" will be useful...I would think that PRI tei would be zero.

http://www.cisco.com/warp/public/116/T1_pri.html

Thanks, Mak.

[hucuncu]

At the time I have entered "debug isdn q921", the following messages were received:

!

Apr 29 09:20:35 MEST200: ISDN Se3/1:15: TX -> SABMEp c/r = 0 sapi = 0 tei = 0

Apr 29 09:20:36 MEST200: ISDN Se3/1:15: TX -> SABMEp c/r = 0 sapi = 0 tei = 0

Apr 29 09:20:37 MEST200: ISDN Se3/1:15: TX -> SABMEp c/r = 0 sapi = 0 tei = 0

Apr 29 09:20:38 MEST200: ISDN Se3/1:15: TX -> SABMEp c/r = 0 sapi = 0 tei = 0

Apr 29 09:20:39 MEST200: ISDN Se3/1:15: Event: received NL_REL_IND

!

While playing with the confuguration of Serial3/1:15, and trying to enter 'dial string' for Dialer 25, suddenly router crashed and reloaded itself immediately. The surprising thing is that ISDN status turned into "MULTIPLE_FRAME_ESTABLISHED"!! All 'dial in' and 'dial out' configurations work now.

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

Router#sh isdn status

Global ISDN Switchtype = primary-net5

ISDN Serial3/1:15 interface

dsl 0, interface ISDN Switchtype = primary-net5

Layer 1 Status:

ACTIVE

Layer 2 Status:

TEI = 0, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED

Layer 3 Status:

0 Active Layer 3 Call(s)

Active dsl 0 CCBs = 0

The Free Channel Mask: 0xFFFF7FFF

Total Allocated ISDN CCBs = 0

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

IOS is 'c3640-is-mz.121-5.T9.bin'. I think there happened something related with an IOS bug. Now on, I will control the proper operation of ISDN PRI link.

Thanks a lot,

Onur

[zahmed · Accepted solution]

Hi Onur,

This sounds like CSCdt42505 (Two different Layer 2 status are reported by sh isdn stat) which was dup'ed to CSCuk23244. The release note of CSCuk23244

says as follows :

Configuring a PRI controller for ISDN with the pri-group command may cause ISDN layer 2 failure to establish. Saving the ISDN configuration and reloading the router will resolve the problem, or performing a shut followed by "no shut" on the PRI controller may also resolve the problem.

So I believe the crash kind of did the similar task to your router and brought the layer 2 up. I think your permenant fix is to upgrade the IOS according to CSCuk23244 or the problem will come up again at some other time.

~Zulfi