ISDN Troubleshooting
1. Check The obvious physical things
Check the cable, plugs etc. FYI the cable should be a straight through CAT 5 cable, not a crossover or rollover.
2. The ISDN NT1 (BT box mounted on wall) has a little green LED on it's front
If this light is not on, then chances are ISDN is not active on that line. (Although I have visited one site and noticed that the little NT1 LED was not working, but ISDN was active)
3. Check the Bearer Channel LED's
On WIC cards these are marked as "B1" and "B2", and on ISDN built in routers such as 801's these are marked on the front as "CH1" and "CH2". On the Cisco 801 there are also "RXD" and "TXD" lights showing whether there is any ISDN traffic.
4. Confirm that the ADSL interface is seen
Using "show version" and visible to the router:
router#show version
...
1 FastEthernet/IEEE 802.3 interface(s)
1 ISDN Basic Rate interface(s) <------------ Yes? 1 ATM network interface(s) 1 Virtual Private Network (VPN) Module(s) 5. Confirm that the ISDN interface is not "shutdown" router#sh ip int brief Interface IP-Address OK? Method Status Protocol BRI0 unassigned YES NVRAM administratively down down ^^^^^^^^^^^^^ interfaces are down by default router#conf t router(conf)#int BRI0 router(conf-int)#no shutdown router(conf-int)# end 4. Confirm if you have an IP All ISDN installations will use a dialer interface to dial out, this interface will normally be given an IP address once connected, so confirm whether the dialer interface has an IP: router#sh ip int brief Interface IP-Address OK? Method Status Protocol BRI0 unassigned YES NVRAM up up Dialer1 217.34.5.190 YES IPCP up up note: if you enter "sh int bri0" this does not always tell you the full truth about the interface status, it may say spoofing: router#sh int bri0 BRI0/0 is up, line protocol is up (spoofing) You are better entering "sh int bri0:1" to show the status of each channel: router#sh int bri0 BRI0:1 is up, line protocol is up ... LCP Open Open: IPCP, CDPCP ... 5. Check ISDN status The "show isdn status" and "show isdn active" commands can be used to find out whether the ISDN interface was able to make any phone calls and whether any phone calls are currently active: router#sh isdn status Global ISDN Switchtype = basic-ni ISDN BRI0 interface dsl 0, interface ISDN Switchtype = basic-ni Layer 1 Status: ACTIVE Layer 2 Status: TEI = 117, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED TEI = 118, Ces = 2, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED Spid Status: TEI 117, ces = 1, state = 5(init) spid1 configured, no LDN, spid1 sent, spid1 valid Endpoint ID Info: epsf = 0, usid = 2, tid = 1 TEI 118, ces = 2, state = 5(init) spid2 configured, no LDN, spid2 sent, spid2 valid Endpoint ID Info: epsf = 0, usid = 4, tid = 1 Layer 3 Status: 0 Active Layer 3 Call(s) Activated dsl 0 CCBs = 0 The Free Channel Mask: 0x80000003 Total Allocated ISDN CCBs = 0 The lines to look out for above are "Layer 1 Status" = ACTIVE and "Layer 2 Status" = MULTIPLE_FRAME_ESTABLISHED router#sh isdn active -------------------------------------------------------------------------------- ISDN ACTIVE CALLS -------------------------------------------------------------------------------- Call Calling Called Remote Seconds Seconds Seconds Charges Type Number Number Name Used Left Idle Units/Currency -------------------------------------------------------------------------------- Out ---N/A--- 1234 7978 Unavail - 2 In 4567 1234 5592 Unavail - -------------------------------------------------------------------------------- Showing calls made in or out!? 6. Make a test call You can test to see if the router is able to make a phone call by issuing the "isdn test call" command, one idea could be to dial your mobile number: router#isdn test call interface bri0 0788xxxx483 00:05:46: BR0/0 DDR: Attempting to dial 0788xxxx483 If the line is OK then the router should dial out. It could also be useful to dial your mobile phone if you do not know the phone number of the ISDN line. 7. Debugs Checking Username and Passwords for PPP are correct: router#debug ppp authentication ... 00:05:46: BRI0:1 CHAP: I CHALLENGE id 3 len 28 from "router2" ... 00:05:46: BRI0:1 CHAP: I RESPONSE id 3 len 28 from "router1" 00:05:46: BRI0:1 CHAP: I SUCCESS id 3 len 4.!!! Checking ISDN events: router#debug isdn events ... 00:05:46: ISDN Se1/0:15: Event: received NL_REL_IND 00:05:46: ISDN Se1/0:15: CCPRI_ReleaseCall(): bchan 31, call ... Checking Q931 events, this debug command displays ISDN call setup and teardown messages: router#debug isdn q931 ... 00:05:46: ISDN BR0: RX <- DISCONNECT pd = 8 callref = 0xAE <---Not Good! 00:05:46: Cause i =0x829F08 - Normal,unspecified or Special intercept, ... Checking Q921 events, to display data link layer (layer 2) access procedures that are taking place at the ISDN interface D channel: router#debug isdn q921 ... 00:05:46: ISDN BR0/0: RX <- RRp sapi = 0 tei = 64 nr = 0 00:05:46: ISDN BR0/0: TX -> RRf sapi = 0 tei = 64 nr = 0
00:05:46: ISDN BR0/0: RX <- RRp sapi = 0 tei = 64 nr = 0
1. Check The obvious physical things
Check the cable, plugs etc. FYI the cable should be a straight through CAT 5 cable, not a crossover or rollover.
2. The ISDN NT1 (BT box mounted on wall) has a little green LED on it's front
If this light is not on, then chances are ISDN is not active on that line. (Although I have visited one site and noticed that the little NT1 LED was not working, but ISDN was active)
3. Check the Bearer Channel LED's
On WIC cards these are marked as "B1" and "B2", and on ISDN built in routers such as 801's these are marked on the front as "CH1" and "CH2". On the Cisco 801 there are also "RXD" and "TXD" lights showing whether there is any ISDN traffic.
4. Confirm that the ADSL interface is seen
Using "show version" and visible to the router:
router#show version
...
1 FastEthernet/IEEE 802.3 interface(s)
1 ISDN Basic Rate interface(s) <------------ Yes? 1 ATM network interface(s) 1 Virtual Private Network (VPN) Module(s) 5. Confirm that the ISDN interface is not "shutdown" router#sh ip int brief Interface IP-Address OK? Method Status Protocol BRI0 unassigned YES NVRAM administratively down down ^^^^^^^^^^^^^ interfaces are down by default router#conf t router(conf)#int BRI0 router(conf-int)#no shutdown router(conf-int)# end 4. Confirm if you have an IP All ISDN installations will use a dialer interface to dial out, this interface will normally be given an IP address once connected, so confirm whether the dialer interface has an IP: router#sh ip int brief Interface IP-Address OK? Method Status Protocol BRI0 unassigned YES NVRAM up up Dialer1 217.34.5.190 YES IPCP up up note: if you enter "sh int bri0" this does not always tell you the full truth about the interface status, it may say spoofing: router#sh int bri0 BRI0/0 is up, line protocol is up (spoofing) You are better entering "sh int bri0:1" to show the status of each channel: router#sh int bri0 BRI0:1 is up, line protocol is up ... LCP Open Open: IPCP, CDPCP ... 5. Check ISDN status The "show isdn status" and "show isdn active" commands can be used to find out whether the ISDN interface was able to make any phone calls and whether any phone calls are currently active: router#sh isdn status Global ISDN Switchtype = basic-ni ISDN BRI0 interface dsl 0, interface ISDN Switchtype = basic-ni Layer 1 Status: ACTIVE Layer 2 Status: TEI = 117, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED TEI = 118, Ces = 2, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED Spid Status: TEI 117, ces = 1, state = 5(init) spid1 configured, no LDN, spid1 sent, spid1 valid Endpoint ID Info: epsf = 0, usid = 2, tid = 1 TEI 118, ces = 2, state = 5(init) spid2 configured, no LDN, spid2 sent, spid2 valid Endpoint ID Info: epsf = 0, usid = 4, tid = 1 Layer 3 Status: 0 Active Layer 3 Call(s) Activated dsl 0 CCBs = 0 The Free Channel Mask: 0x80000003 Total Allocated ISDN CCBs = 0 The lines to look out for above are "Layer 1 Status" = ACTIVE and "Layer 2 Status" = MULTIPLE_FRAME_ESTABLISHED router#sh isdn active -------------------------------------------------------------------------------- ISDN ACTIVE CALLS -------------------------------------------------------------------------------- Call Calling Called Remote Seconds Seconds Seconds Charges Type Number Number Name Used Left Idle Units/Currency -------------------------------------------------------------------------------- Out ---N/A--- 1234 7978 Unavail - 2 In 4567 1234 5592 Unavail - -------------------------------------------------------------------------------- Showing calls made in or out!? 6. Make a test call You can test to see if the router is able to make a phone call by issuing the "isdn test call" command, one idea could be to dial your mobile number: router#isdn test call interface bri0 0788xxxx483 00:05:46: BR0/0 DDR: Attempting to dial 0788xxxx483 If the line is OK then the router should dial out. It could also be useful to dial your mobile phone if you do not know the phone number of the ISDN line. 7. Debugs Checking Username and Passwords for PPP are correct: router#debug ppp authentication ... 00:05:46: BRI0:1 CHAP: I CHALLENGE id 3 len 28 from "router2" ... 00:05:46: BRI0:1 CHAP: I RESPONSE id 3 len 28 from "router1" 00:05:46: BRI0:1 CHAP: I SUCCESS id 3 len 4.!!! Checking ISDN events: router#debug isdn events ... 00:05:46: ISDN Se1/0:15: Event: received NL_REL_IND 00:05:46: ISDN Se1/0:15: CCPRI_ReleaseCall(): bchan 31, call ... Checking Q931 events, this debug command displays ISDN call setup and teardown messages: router#debug isdn q931 ... 00:05:46: ISDN BR0: RX <- DISCONNECT pd = 8 callref = 0xAE <---Not Good! 00:05:46: Cause i =0x829F08 - Normal,unspecified or Special intercept, ... Checking Q921 events, to display data link layer (layer 2) access procedures that are taking place at the ISDN interface D channel: router#debug isdn q921 ... 00:05:46: ISDN BR0/0: RX <- RRp sapi = 0 tei = 64 nr = 0 00:05:46: ISDN BR0/0: TX -> RRf sapi = 0 tei = 64 nr = 0
00:05:46: ISDN BR0/0: RX <- RRp sapi = 0 tei = 64 nr = 0
