LanzaBradshaw321

To earn your Cisco CCNA and CCNP certifications, you have got to master ISDN - and in spite of what some men and women say, there is nevertheless a lot of ISDN out there that wants to be supported. And when it comes to troubleshooting ISDN, there's a lot to look at. Is the appropriate ISDN switchtype configured? Are the dialer map statements right? What about the dialer-group and dialer-list commands? And that is just the commence.

I always say that all troubleshooting begins at Layer 1, the Physical layer of the OSI model. The usual strategy of troubleshooting ISDN is sending pings across the hyperlink, but the connection can be tested with out utilizing pings or even just before assigning IP addresses to the BRI interfaces!

It's a excellent notion to spot these test calls prior to configuring the interfaces - that way, you know you have got a valid connection ahead of beginning the configuration (and there's a lot of config to go along with ISDN!)

To place a test contact without having utilizing pings, use the isdn contact interface command.

R1#isdn get in touch with interface bri0 8358662

R1#

03:54:43: BR0 DDR: Attempting to dial 8358662

03:54:43: %Link-3-UPDOWN: Interface BRI0:1, changed state to up

03:54:44: BR0:1 DDR: dialer protocol up

03:54:45: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state to up

03:54:49: %ISDN-six-CONNECT: Interface BRI0:1 is now connected to 8358662 R2

To tear the test call down properly, use isdn disconnect interface. IOS Assist displays the options with this command.

R1#isdn disconnect interface bri  ?

all Disconnect the information contact(s) on all b channels

b1 Disconnect the information call on b1 channel

b2 Disconnect the information call on b2 channel

R1#isdn disconnect interface bri all

03:58:36: BR0:1 DDR: disconnecting call

03:58:36: BR0:two DDR: disconnecting contact

03:58:36: %ISDN-six-DISCONNECT: Interface BRI0:1 disconnected from 8358662

R2, call lasted 20 seconds

03:58:36: %Hyperlink-three-UPDOWN: Interface BRI0:1, changed state to down

03:58:36: BR0:1 DDR: disconnecting get in touch with

03:58:37: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state to down

I say "properly" since the one point you never want to do to finish an ISDN contact, test or otherwise, is just shut the interface. Telcos never like it, and ISDN lab devices like it even less. Always let the d-channel do its function and tear the get in touch with down in an orderly style - do not just cut it off by shutting the interface down.SDM Software, Inc. 2100 4th St, #132 San Rafael, CA 94901 (415) 670-9302 http://sdmsoftware.com research gpo management