BRI Backup interface question

[sean_woods]

I am confused about the way a backup interface can be tested. I have come across a testing mechanism whereby the backup interface is removed as a means of testing whether or not it works.

The configuration is as follows:

router01(config)#int se0.3

router01(config-subif)#no backup int bri2

router01(config-subif)#^Z

Followed by:

#sh isdn stat

.

.

ISDN BRI2 interface

Layer 1 Status:

ACTIVE

Layer 2 Status:

TEI = 64, State = MULTIPLE_FRAME_ESTABLISHED

Layer 3 Status:

1 Active Layer 3 Call(s)

Activated dsl 2 CCBs = 1

And finally:

#sh isdn active

.

.

Out XXXXXXXXXXXX Active(72) router02 118

I realise this may appear obvious to some, but I would appreciate it if it could be explained.

Cheers.

[bwilmoth · Accepted solution]

I think if you have configured the route, that will make the ISDN interface to dial, even though the backup interface is removed.

http://www.cisco.com/en/US/tech/tk801/tk133/technologies_tech_note09186a0080093c6d.shtml

[sanilsadasivan]

I think u have to give the backup delay command also along with the backup interface command to activatite the primary line. the bri interface wouldnt know when to disconnect .otherwise u have to manually clear the interface and then try

sanil