. To earn your Cisco CCNA and CCNP certifications, you have got to master ISDN - and in spite of what some folks say, there is still a lot of ISDN out there that requirements to be supported. And when it comes to troubleshooting ISDN, there is a lot to look at <a href=“http://www.youtube.com/watch?v=EE393__fBW8”>group policy manager</a> . Is the appropriate ISDN switchtype configured? Are the dialer map statements correct? What about the dialer-group and dialer-list commands? And that is just the start.

I usually 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 link, but the connection can be tested without having making use of pings or even prior to assigning IP addresses to the BRI interfaces!

It really is a very good notion to place these test calls prior to configuring the interfaces - that way, you know you have got a valid connection before starting the configuration (and there is a lot of config to go along with ISDN!)

To location a test get in touch with without employing pings, use the isdn get in touch with interface command.

R1#isdn call interface bri0 8358662

R1#

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

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

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

03:54:45: %LINEPROTO-five-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 get in touch with down appropriately, use isdn disconnect interface group policy tools . IOS Support displays the possibilities with this command.

R1#isdn disconnect interface bri ?

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

b1 Disconnect the data get in touch with on b1 channel

b2 Disconnect the data call on b2 channel

R1#isdn disconnect interface bri all

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

03:58:36: BR0:2 DDR: disconnecting contact

03:58:36: %ISDN-6-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 contact

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

I say “correctly” simply because the one point you never want to do to finish an ISDN get in touch with, test or otherwise, is just shut the interface. Telcos never like it, and ISDN lab devices like it even less per your request . Often let the d-channel do its perform and tear the contact down in an orderly style - never 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