Trouble Ticket Solutions
These solutions are not always the only way to perform these tasks. Compare your results.
Trouble Ticket 1 Solution
Turn on the debug bri command in Example 9-51 to watch the TEI negotiation.
Example 9-51. TEI Negotiation
r5#debug bri Basic Rate network interface debugging is on r5#!!!unplug the cable Dec 23 06:51:14.784: BRI: write_sid: scp = 0, wrote = E Dec 23 06:51:14.792: BRI: write_sid: scp = 0, wrote = E Dec 23 06:51:14.792: BRI: write_sid: scp = 0, wrote = E Dec 23 06:51:25.404: BRI: write_sid: scp = 0, wrote = 92 Dec 23 06:51:25.404: BRI: write_sid: scp = 90, wrote = 93 Dec 23 06:51:25.408: BRI0: ACTIVATED, state F2, event DI Dec 23 06:51:25.408: BRI: T4 timer started DEACT timer expired Dec 23 06:51:26.012: BRI: write_sid: scp = 0, wrote = 92 Dec 23 06:51:26.012: BRI: write_sid: scp = 90, wrote = 93 Dec 23 06:51:26.016: BRI: write_sid: scp = 0, wrote = 1 Dec 23 06:51:26.016: BRI: write_sid: scp = 0, wrote = 0 Dec 23 06:51:26.020: isdn_Call_disconnect() Dec 23 06:51:26.020: isdn_Call_disconnect() Dec 23 06:51:26.024: BRI: disable channel B1 Dec 23 06:51:26.024: BRI: disable channel B2 r5#show isdn status Global ISDN Switchtype = basic-ni ISDN BRI0 interface dsl 0, interface ISDN Switchtype = basic-ni Layer 1 Status: DEACTIVATED Layer 2 Status: TEI = 118, Ces = 1, SAPI = 0, State = TEI_ASSIGNED TEI = 119, Ces = 2, SAPI = 0, State = TEI_ASSIGNED Spid Status: TEI 118, ces = 1, state = 5(init) spid1 configured, spid1 sent, spid1 valid Endpoint ID Info: epsf = 0, usid = 2, tid = 1 TEI 119, ces = 2, state = 5(init) spid2 configured, spid2 sent, spid2 valid Endpoint ID Info: epsf = 0, usid = 4, tid = 1 ... r5#!!!plug cable back in Dec 23 06:52:11.132: BRI: write_sid: scp = 0, wrote = 92 Dec 23 06:52:11.132: BRI: write_sid: scp = 80, wrote = 93 Dec 23 06:52:11.132: BRI0: DEACTIVATED, state F1, event LSD Dec 23 06:52:11.136: BRI: write_sid: scp = 0, wrote = 1B Dec 23 06:52:11.140: BRI: write_sid: scp = 0, wrote = 20 Dec 23 06:52:11.200: BRI: write_sid: scp = 0, wrote = 92 Dec 23 06:52:11.200: BRI: write_sid: scp = A0, wrote = 93 Dec 23 06:52:11.204: BRI0: DEACTIVATED, state F3, event AP Dec 23 06:52:11.204: BRI: write_sid: scp = 0, wrote = 3 Dec 23 06:52:11.216: BRI: write_sid: scp = 0, wrote = 92 Dec 23 06:52:11.216: BRI: write_sid: scp = E0, wrote = 93 Dec 23 06:52:11.216: BRI0: PENDING, state F7, event AI Dec 23 06:52:11.220: BRI: Received activation indication. Dec 23 06:52:11.232: BRI: write_sid: scp = 0, wrote = E Dec 23 06:52:11.388: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BRI0, TEI 118 changed to down Dec 23 06:52:11.388: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BRI0, TEI 119 changed to down Dec 23 06:52:11.392: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BR0, TEI 118 changed to down Dec 23 06:52:11.420: BRI: write_sid: scp = 0, wrote = E Dec 23 06:52:13.420: BRI: write_sid: scp = 0, wrote = E Dec 23 06:52:13.532: BRI: write_sid: scp = 0, wrote = E Dec 23 06:52:13.556: %ISDN-6-LAYER2UP: Layer 2 for Interface BR0, TEI 70 changed to up Dec 23 06:52:13.564: BRI: write_sid: scp = 0, wrote = E Dec 23 06:52:13.644: BRI: write_sid: scp = 0, wrote = E Dec 23 06:52:13.664: BRI: write_sid: scp = 0, wrote = E Dec 23 06:52:13.700: BRI: write_sid: scp = 0, wrote = E Dec 23 06:52:13.724: %ISDN-6-LAYER2UP: Layer 2 for Interface BR0, TEI 71 changed to up Dec 23 06:52:13.732: BRI: write_sid: scp = 0, wrote = E Dec 23 06:52:13.816: BRI: write_sid: scp = 0, wrote = E r5#no debug bri |
This is a little more output than you want occurring on a regular basis, so keep that in mind to find the best time to issue the command. The output continuously displays write sid, which is an internal command written to the interface controller subunit identifier (SID). With the cable unplugged, the activation timer (T3) expired and the status was F2. The timers deactivated, the call terminated, and both B channels went down. Also note the Layer2Down messages. In summary, if there are quick BRI interface changes, always check the Physical Layer, such as the cable or interface. Unless you want to see all the TEI negotiation in the background, however, show isdn status is still the best tool for troubleshooting ISDN layers.
Trouble Ticket 2 Solution
The obvious issue is the missing ISDN switch type or mismatch that show isdn status reveals quite nicely. When Layer 1 is deactivated, you should immediately suspect a bad cable or the switch type. You might want to take a few minutes and remove your switch type as in the following output and then fix the issues. Glance at the output of show isdn status in Example 9-52 before you make any changes. Note any complications.
Example 9-52. show isdn status Command Output
r5#show 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 = 70, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED TEI = 71, Ces = 2, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED Spid Status: TEI 70, ces = 1, state = 5(init) spid1 configured, spid1 sent, spid1 valid Endpoint ID Info: epsf = 0, usid = 2, tid = 1 TEI 71, ces = 2, state = 5(init) spid2 configured, 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 |
Now remove both the global interface switch types for r5 in Example 9-53.
Example 9-53. Removing the ISDN Switch Types
r5(config)#interface bri0 r5(config-if)#no isdn switch-type Warning: No ISDN switch-type defined. No calls possible. r5(config-if)#exit Dec 23 07:09:52.456: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BR0, TEI 70 changed to down Dec 23 07:09:52.460: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BRI0, TEI 70 changed to down Dec 23 07:09:52.628: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BR0, TEI 71 changed to down Dec 23 07:09:52.632: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BRI0, TEI 71 changed to down r5(config)#no isdn switch-type Warning: No ISDN switch-type defined. No calls possible, unless switchtype defined |
Globally and/or per interface.The main complication to note is that when you completely remove the ISDN switch type the router warns you that no calls are possible. It also does not take effect until you reload the router. Just like other features, however, you may run into slight differences with the version of code.
Trouble Ticket 3 Solution
First remove your SPIDs from r5 as in Example 9-54. Then clear the BRI interface and show the ISDN status.
Example 9-54. Removing SPIDs
r5#show run interface bri0 interface BRI0 ip address 192.168.9.22 255.255.255.252 no ip directed-broadcast dialer idle-timeout 55 dialer map ip 192.168.9.21 name r6 8358661 dialer map ip 192.168.9.21 name r6 8358663 isdn switch-type basic-ni isdn spid1 0835866201 8358662 isdn spid2 0835866401 8358664 end r5#configure terminal r5(config)#interface bri0 r5(config-if)#no isdn spid1 0835866201 8358662 r5(config-if)#no isdn spid2 0835866401 8358664 r5(config-if)#end r5#clear interface bri0 Dec 23 07:24:13.107: isdn_Call_disconnect() Dec 23 07:24:13.111: isdn_Call_disconnect() Dec 23 07:24:13.299: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BRI0, TEI 72 changed to down Dec 23 07:24:13.303: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BRI0, TEI 73 changed to down Dec 23 07:24:13.307: %ISDN-6-LAYER2DOWN: Layer 2 for Interface BR0, TEI 72 changed to down Dec 23 07:24:14.111: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state to down Dec 23 07:24:14.115: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:2, changed state to down Dec 23 07:24:15.475: %ISDN-6-LAYER2UP: Layer 2 for Interface BR0, TEI 74 changed to up r5#show 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 = 74, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED Layer 3 Status: 0 Active Layer 3 Call(s) Activated dsl 0 CCBs = 0 The Free Channel Mask: 0x80000003 Total Allocated ISDN CCBs = 0 |
Note how I first issued the show run interface bri0 command so that I had the commands right in front of me that I wanted to delete. I used clear interface bri0 to clear the interface so that this would take effect. TEI was not assigned as you can see by the SPID status. Now add one SPID back at a time and observe the results in Example 9-55.
Example 9-55. Configuring SPIDs (First B Channel)
r5#!!!add one SPID back at a time r5#configure terminal r5(config)#interface bri0 r5(config-if)#isdn spid1 0835866201 8358662 r5(config-if)#end r5#clear interface bri0 r5#show 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 = 75, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED Spid Status: TEI 75, ces = 1, state = 5(init) spid1 configured, spid1 sent, spid1 valid Endpoint ID Info: epsf = 0, usid = 2, 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 |
Focus on the ISDN Layer 2 status. Your key is the MULTIPLE_FRAME_ESTABLISHED state for each B channel. When you removed both SPIDs and added one back, however, you only saw one MULTIPLE_FRAME_ESTABLISHED. Add the other SPID back in Example 9-56 and observe the results.
Example 9-56. Configuring SPIDs (Second B Channel)
r5#!!!now add the other SPID r5#configure terminal r5(config)#interface bri0 r5(config-if)#isdn spid2 0835866401 8358664 r5(config-if)#end r5#clear interface bri0 r5#show 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 = 76, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED TEI = 77, Ces = 2, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED Spid Status: TEI 76, ces = 1, state = 5(init) spid1 configured, spid1 sent, spid1 valid Endpoint ID Info: epsf = 0, usid = 2, tid = 1 TEI 77, ces = 2, state = 5(init) spid2 configured, spid2 sent, spid2 valid Endpoint ID Info: epsf = 0, usid = 4, tid = 1 |
The moral of this ticket is MULTIPLE_FRAME_ESTABLISHED and valid SPIDs. The tool is show isdn status.
Trouble Ticket 4 Solution
Configure PPP encapsulation with PAP authentication on the ISDN bri0 interfaces to produce the configurations in Example 9-57.
Example 9-57. Configuring PPP Encapsulation and PAP Authentication
r5#show running-config hostname r5 enable password cisco username r6 password 0 donna ip subnet-zero isdn switch-type basic-ni ... interface Loopback8 ip address 5.5.5.5 255.255.255.255 no ip directed-broadcast ! interface Serial0 bandwidth 64 ip address 192.168.9.14 255.255.255.252 no ip directed-broadcast encapsulation ppp no ip mroute-cache ! interface Serial1 bandwidth 64 ip address 192.168.9.18 255.255.255.252 no ip directed-broadcast encapsulation ppp ppp authentication chap ! interface BRI0 ip address 192.168.9.22 255.255.255.252 no ip directed-broadcast encapsulation ppp dialer idle-timeout 55 dialer map ip 192.168.9.21 name r6 8358661 dialer map ip 192.168.9.21 name r6 8358663 dialer-group 1 isdn switch-type basic-ni isdn spid1 0835866201 8358662 isdn spid2 0835866401 8358664 ppp authentication pap callin ppp pap sent-username paplady password 7 0117090A550A ... end r6#show running-config hostname r6 ! username r5 password 0 donna username paplady password 0 donna ip subnet-zero isdn switch-type basic-ni ! interface Loopback9 ip address 6.6.6.6 255.255.255.255 no ip directed-broadcast ! interface Serial0 bandwidth 64 ip address 192.168.9.17 255.255.255.252 no ip directed-broadcast encapsulation ppp no ip mroute-cache clockrate 64000 ppp authentication chap ! ... interface BRI0 ip address 192.168.9.21 255.255.255.252 no ip directed-broadcast encapsulation ppp dialer idle-timeout 55 dialer map ip 192.168.9.22 name r5 8358662 dialer map ip 192.168.9.22 name r5 8358664 dialer-group 1 isdn switch-type basic-ni isdn spid1 0835866101 8358661 isdn spid2 0835866301 8358663 ppp authentication pap ... end |
Turn on the debug ppp negotiation command to watch the authentication process in Example 9-58.
Example 9-58. Debug PPP Negotiation over ISDN
r5#debug ppp negotiation PPP protocol negotiation debugging is on r5#ping 192.168.9.21 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.9.21, timeout is 2 seconds: .!!!! Success rate is 80 percent (4/5), round-trip min/avg/max = 36/37/40 ms Dec 23 08:11:17.355: %LINK-3-UPDOWN: Interface BRI0:1, changed state to up Dec 23 08:11:17.391: %ISDN-6-CONNECT: Interface BRI0:1 is now connected to 8358661 Dec 23 08:11:17.399: BR0:1 PPP: Treating connection as a callout Dec 23 08:11:17.399: BR0:1 PPP: Phase is ESTABLISHING, Active Open Dec 23 08:11:17.403: BR0:1 PPP: No remote authentication for call-out Dec 23 08:11:17.403: BR0:1 LCP: O CONFREQ [Closed] id 3 len 10 Dec 23 08:11:17.407: BR0:1 LCP: MagicNumber 0x0042EEFD (0x05060042EEFD) Dec 23 08:11:17.423: BR0:1 LCP: I CONFREQ [REQsent] id 3 len 14 Dec 23 08:11:17.427: BR0:1 LCP: AuthProto PAP (0x0304C023) Dec 23 08:11:17.431: BR0:1 LCP: MagicNumber 0x172FC497 (0x0506172FC497) Dec 23 08:11:17.431: BR0:1 LCP: O CONFACK [REQsent] id 3 len 14 Dec 23 08:11:17.435: BR0:1 LCP: AuthProto PAP (0x0304C023) Dec 23 08:11:17.439: BR0:1 LCP: MagicNumber 0x172FC497 (0x0506172FC497) Dec 23 08:11:17.443: BR0:1 LCP: I CONFACK [ACKsent] id 3 len 10 Dec 23 08:11:17.443: BR0:1 LCP: MagicNumber 0x0042EEFD (0x05060042EEFD) Dec 23 08:11:17.447: BR0:1 LCP: State is Open Dec 23 08:11:17.451: BR0:1 PPP: Phase is AUTHENTICATING, by the peer Dec 23 08:11:17.459: BR0:1 PAP: O AUTH-REQ id 3 len 18 from "paplady" Dec 23 08:11:17.475: BR0:1 PAP: I AUTH-ACK id 3 len 5 Dec 23 08:11:17.479: BR0:1 PPP: Phase is UP Dec 23 08:11:17.483: BR0:1 IPCP: O CONFREQ [Closed] id 3 len 10 Dec 23 08:11:17.487: BR0:1 IPCP: Address 192.168.9.22 (0x0306C0A80916) Dec 23 08:11:17.491: BR0:1 CDPCP: O CONFREQ [Closed] id 3 len 4 Dec 23 08:11:17.495: BR0:1 IPCP: I CONFREQ [REQsent] id 3 len 10 Dec 23 08:11:17.495: BR0:1 IPCP: Address 192.168.9.21 (0x0306C0A80915) Dec 23 08:11:17.499: BR0:1 IPCP: O CONFACK [REQsent] id 3 len 10 Dec 23 08:11:17.503: BR0:1 IPCP: Address 192.168.9.21 (0x0306C0A80915) Dec 23 08:11:17.507: BR0:1 CDPCP: I CONFREQ [REQsent] id 3 len 4 Dec 23 08:11:17.511: BR0:1 CDPCP: O CONFACK [REQsent] id 3 len 4 Dec 23 08:11:17.515: BR0:1 IPCP: I CONFACK [ACKsent] id 3 len 10 Dec 23 08:11:17.519: BR0:1 IPCP: Address 192.168.9.22 (0x0306C0A80916) Dec 23 08:11:17.519: BR0:1 IPCP: State is Open Dec 23 08:11:17.523: BR0:1 CDPCP: I CONFACK [ACKsent] id 3 len 4 Dec 23 08:11:17.527: BR0:1 CDPCP: State is Open Dec 23 08:11:17.535: BR0 IPCP: Install route to 192.168.9.21 Dec 23 08:11:18.479: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state to up Dec 23 08:11:23.395: %ISDN-6-CONNECT: Interface BRI0:1 is now connected to 8358661 r6 !!!now for the disconnect Dec 23 08:12:14.115: %ISDN-6-DISCONNECT: Interface BRI0:1 disconnected from 8358661 r6, |
PAP is a one-way challenge performed one time. Notice the authentication request and acknowledgment. The commands debug ppp authentication and debug ppp negotiation are quite helpful in troubleshooting authentication issues. In my test, r5 was the calling router and r6 was the called router. Reference the CCO “Configuring and Troubleshooting PAP” Tech Note at Cisco.com for more detail.
Trouble Ticket 5 Solution
Refer back to the initial chapter scenario in Figure 9-1 for the physical layout of your lab. Use Figure 9-9 as a more detailed view of r5 and r6. Configure IS-IS on r5 and r6 as in Example 9-59. If you want to see more of what is going on you can log the adjacency changes for IS-IS.
Example 9-59. Configuring IS-IS on r5 and r6
r5#configure terminal r5(config)#router isis r5(config-router)#net ? XX.XXXX. ... .XXX.XX Network entity title (NET) r5(config-router)#net 49.0001.5555.5555.00 r5(config-router)#interface s1 r5(config-if)#ip router isis Dec 23 08:20:26.927: Se1 PPP: Outbound clns_es packet dropped, OSICP is Closed [starting negotiations] Dec 23 08:20:26.927: Se1 OSICP: State is Listen Dec 23 08:20:26.931: Se1 OSICP: TIMEout: State Listen Dec 23 08:20:26.935: Se1 OSICP: O CONFREQ [Listen] id 1 len 4 Dec 23 08:20:26.947: Se1 LCP: I PROTREJ [Open] id 47 len 10 protocol OSICP (0x802301010004) Dec 23 08:20:26.947: Se1 OSICP: State is Closed Dec 23 08:20:27.083: Se1 PPP: Outbound clns_is packet dropped, OSICP is Closed [starting negotiations] Dec 23 08:20:27.087: Se1 OSICP: State is Closed Dec 23 08:20:27.091: Se1 OSICP: TIMEout: State Closed Dec 23 08:20:27.091: Se1 OSICP: State is Listen r5(config-if)#interface loopback 8 r5(config-if)#ip router isis r5(config-if)#router eigrp 109 !!!no need to send any eigrp advertisements on s1 or lo8 r5(config-router)#passive-interface s1 r5(config-router)#passive-interface lo8 r5(config-router)#end r5#copy running-config startup-config r6#configure terminal r6(config)#no router eigrp 109 r6(config)#router isis r6(config-router)#net 49.0001.6666.6666.00 r6(config-router)#interface s0 r6(config-if)#ip router isis r6(config-if)#interface loopback 9 r6(config-if)#ip router isis r6(config-if)#end r6#copy running-config startup-config |
Now that IS-IS is configured, view your neighbors, the topology, the database, and your interfaces in Example 9-60.
Example 9-60. Verifying IS-IS
r6#show clns neighbors System Id Interface SNPA State Holdtime Type Protocol 0001.5555.5555 Se0 *PPP* Up 28 L1L2 IS-IS r6#show isis ? database IS-IS link state database mesh-groups IS-IS mesh groups route IS-IS level-1 routing table spf-log IS-IS SPF log topology IS-IS paths to Intermediate Systems r6#show isis topology IS-IS paths to level-1 routers System Id Metric Next-Hop Interface SNPA 0001.5555.5555 10 0001.5555.5555 Se0 *PPP* 0001.6666.6666 -- IS-IS paths to level-2 routers System Id Metric Next-Hop Interface SNPA 0001.5555.5555 10 0001.5555.5555 Se0 *PPP* 0001.6666.6666 -- r6#show isis database IS-IS Level-1 Link State Database LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL 0001.5555.5555.00-00 0x00000004 0x58C6 1043 0/0/0 0001.5555.5555.01-00 0x00000001 0x3DF8 934 0/0/0 0001.6666.6666.00-00* 0x00000004 0x8FFE 1053 0/0/0 0001.6666.6666.01-00* 0x00000001 0x0AA3 1057 0/0/0 IS-IS Level-2 Link State Database LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL 0001.5555.5555.00-00 0x00000005 0x68C5 1053 0/0/0 0001.6666.6666.00-00* 0x00000005 0x18CC 1058 0/0/0 r6# r6#show ip interface brief Interface IP-Address OK? Method Status Protocol BRI0 192.168.9.21 YES manual up up BRI0:1 unassigned YES unset down down BRI0:2 unassigned YES unset down down Ethernet0 unassigned YES unset administratively down down Loopback9 6.6.6.6 YES NVRAM up up Serial0 192.168.9.17 YES NVRAM up up Serial1 unassigned YES unset administratively down down Serial2 unassigned YES unset administratively down down Serial3 unassigned YES unset administratively down down r6#show clns interface s0 Serial0 is up, line protocol is up Checksums enabled, MTU 1500, Encapsulation PPP ERPDUs enabled, min. interval 10 msec. RDPDUs enabled, min. interval 100 msec., Addr Mask enabled Congestion Experienced bit set at 4 packets CLNS fast switching enabled CLNS SSE switching disabled DEC compatibility mode OFF for this interface Next ESH/ISH in 49 seconds Routing Protocol: IS-IS Circuit Type: level-1-2 Interface number 0x0, local circuit ID 0x100 Level-1 Metric: 10, Priority: 64, Circuit ID: 0001.6666.6666.00 Number of active level-1 adjacencies: 1 Level-2 Metric: 10, Priority: 64, Circuit ID: 0001.6666.6666.00 Number of active level-2 adjacencies: 1 Next IS-IS Hello in 5 seconds |
If for some reason you do not have neighbors or adjacencies, don't assume it is an IS-IS issue. You have made lots of encapsulation changes in this chapter, and I would expect that to be a major target here. The debug isis adj-packets command in Example 9-61 can help you determine such issues.
Example 9-61. debug isis adj-packets
r5#debug isis adj-packets IS-IS Adjacency related packets debugging is on r5# Jul 20 07:10:34: ISIS-Adj: Sending L2 IIH on Loopback8 Jul 20 07:10:34: ISIS-Adj: Sending L1 IIH on Loopback8 Jul 20 07:10:36: ISIS-Adj: Sending L1 IIH on Loopback8 Jul 20 07:10:37: ISIS-Adj: Sending L2 IIH on Loopback8 Jul 20 07:10:38: ISIS-Adj: Encapsulation failed on serial IIH (Serial1) ... r5#undebug all |
Change the encapsulation of r5s1 and r6s0 to HDLC as in Example 9-62. If you did not experience the “encapsulation failed” message in Example 9-61, you certainly can force that to happen here between your configuration of r5 and r6. Display the routing tables on both r5 and r6 to verify reachability information to all subnets in Example 9-63.
Example 9-62. HDLC Encapsulation
r5(config)#interface s1 r5(config-if)#shut r5(config-if)#encap hdlc r5(config-if)#no shut r6(config)#interface s0 r6(config-if)#shut r6(config-if)#encap hdlc r6(config-if)#no shut |
Example 9-63. Routing Tables
r5#show ip route 1.0.0.0/32 is subnetted, 1 subnets D 1.1.1.1 [90/41152000] via 192.168.9.13, 00:01:33, Serial0 2.0.0.0/32 is subnetted, 1 subnets D 2.2.2.2 [90/41152000] via 192.168.9.13, 00:01:33, Serial0 3.0.0.0/32 is subnetted, 1 subnets D 3.3.3.3 [90/40640000] via 192.168.9.13, 00:01:33, Serial0 4.0.0.0/32 is subnetted, 1 subnets D 4.4.4.4 [90/41152000] via 192.168.9.13, 00:01:33, Serial0 192.168.9.0/24 is variably subnetted, 10 subnets, 2 masks D 192.168.9.1/32 [90/41024000] via 192.168.9.13, 00:01:33, Serial0 D 192.168.9.0/30 [90/41024000] via 192.168.9.13, 00:01:33, Serial0 D 192.168.9.4/30 [90/41024000] via 192.168.9.13, 00:01:34, Serial0 D 192.168.9.6/32 [90/41024000] via 192.168.9.13, 00:01:34, Serial0 D 192.168.9.8/30 [90/41024000] via 192.168.9.13, 00:01:34, Serial0 D 192.168.9.10/32 [90/41024000] via 192.168.9.13, 00:01:35, Serial0 C 192.168.9.13/32 is directly connected, Serial0 C 192.168.9.12/30 is directly connected, Serial0 C 192.168.9.16/30 is directly connected, Serial1 C 192.168.9.20/30 is directly connected, BRI0 5.0.0.0/32 is subnetted, 1 subnets C 5.5.5.5 is directly connected, Loopback8 6.0.0.0/32 is subnetted, 1 subnets i L1 6.6.6.6 [115/20] via 192.168.9.17, Serial1 r6#show ip route 192.168.9.0/30 is subnetted, 2 subnets C 192.168.9.16 is directly connected, Serial0 C 192.168.9.20 is directly connected, BRI0 5.0.0.0/32 is subnetted, 1 subnets i L1 5.5.5.5 [115/20] via 192.168.9.18, Serial0 6.0.0.0/32 is subnetted, 1 subnets C 6.6.6.6 is directly connected, Loopback9 |
Instead of redistributing between IS-IS and EIGRP on r5, have r5 advertise a default route via IS-IS as in Example 9-64. Verify connectivity via the loopbacks.
Example 9-64. Advertising a Default Route
r5#configure terminal r5(config)#router isis r5(config-router)#default-information originate r5(config-router)#end r6#show ip route Gateway of last resort is 192.168.9.18 to network 0.0.0.0 192.168.9.0/30 is subnetted, 2 subnets C 192.168.9.16 is directly connected, Serial0 C 192.168.9.20 is directly connected, BRI0 5.0.0.0/32 is subnetted, 1 subnets i L1 5.5.5.5 [115/20] via 192.168.9.18, Serial0 6.0.0.0/32 is subnetted, 1 subnets C 6.6.6.6 is directly connected, Loopback9 i*L2 0.0.0.0/0 [115/10] via 192.168.9.18, Serial0 r6#ping 1.1.1.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 88/88/92 ms = 4/4/4 ms r6#copy running-config startup-config r5#copy running-config startup-config |
In your earlier testing, you should have noticed that r6 did not have a route to get to the remote networks. With the default-information originate command, IS-IS sent a default route to the others regardless of whether a default route existed in the routing table.
Remove the IS-IS default-information originate and any other static/default routes in r5 and r6. Configure one-way redistribution from EIGRP into IS-IS on r5 as in Example 9-65.
Example 9-65. Redistributing EIGRP into IS-IS
r5(config-router)#redistribute eigrp 109 metric ? <0-63> ISIS default metric r5(config-router)#redistribute eigrp 109 metric 50 r5(config-router)#end r5#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is not set 1.0.0.0/32 is subnetted, 1 subnets D 1.1.1.1 [90/41152000] via 192.168.9.13, 00:07:53, Serial0 2.0.0.0/32 is subnetted, 1 subnets D 2.2.2.2 [90/41152000] via 192.168.9.13, 00:07:54, Serial0 3.0.0.0/32 is subnetted, 1 subnets D 3.3.3.3 [90/40640000] via 192.168.9.13, 00:07:54, Serial0 4.0.0.0/32 is subnetted, 1 subnets D 4.4.4.4 [90/41152000] via 192.168.9.13, 00:07:54, Serial0 192.168.9.0/24 is variably subnetted, 9 subnets, 2 masks D 192.168.9.1/32 [90/41024000] via 192.168.9.13, 00:07:54, Serial0 D 192.168.9.0/30 [90/41024000] via 192.168.9.13, 00:07:54, Serial0 D 192.168.9.4/30 [90/41024000] via 192.168.9.13, 00:07:54, Serial0 D 192.168.9.6/32 [90/41024000] via 192.168.9.13, 00:07:54, Serial0 D 192.168.9.8/30 [90/41024000] via 192.168.9.13, 00:07:54, Serial0 D 192.168.9.10/32 [90/41024000] via 192.168.9.13, 00:07:55, Serial0 C 192.168.9.12/30 is directly connected, Serial0 C 192.168.9.16/30 is directly connected, Serial1 C 192.168.9.20/30 is directly connected, BRI0 5.0.0.0/32 is subnetted, 1 subnets C 5.5.5.5 is directly connected, Loopback8 6.0.0.0/32 is subnetted, 1 subnets i L1 6.6.6.6 [115/20] via 192.168.9.17, Serial1 r6#show ip route 1.0.0.0/32 is subnetted, 1 subnets i L2 1.1.1.1 [115/60] via 192.168.9.18, Serial0 2.0.0.0/32 is subnetted, 1 subnets i L2 2.2.2.2 [115/60] via 192.168.9.18, Serial0 3.0.0.0/32 is subnetted, 1 subnets i L2 3.3.3.3 [115/60] via 192.168.9.18, Serial0 4.0.0.0/32 is subnetted, 1 subnets i L2 4.4.4.4 [115/60] via 192.168.9.18, Serial0 192.168.9.0/24 is variably subnetted, 9 subnets, 2 masks i L2 192.168.9.1/32 [115/60] via 192.168.9.18, Serial0 i L2 192.168.9.0/30 [115/60] via 192.168.9.18, Serial0 i L2 192.168.9.4/30 [115/60] via 192.168.9.18, Serial0 i L2 192.168.9.6/32 [115/60] via 192.168.9.18, Serial0 i L2 192.168.9.8/30 [115/60] via 192.168.9.18, Serial0 i L2 192.168.9.10/32 [115/60] via 192.168.9.18, Serial0 S 192.168.9.12/30 [1/0] via 192.168.9.22 C 192.168.9.16/30 is directly connected, Serial0 C 192.168.9.20/30 is directly connected, BRI0 5.0.0.0/32 is subnetted, 1 subnets i L1 5.5.5.5 [115/20] via 192.168.9.18, Serial0 6.0.0.0/32 is subnetted, 1 subnets C 6.6.6.6 is directly connected, Loopback9 |
The issues with this Trouble Ticket were not so much IS-IS issues but mismatched encapsulation issues and lower-level WAN interface targets. However, the debug isis adj-packets command quickly identified encapsulation issues. Like OSPF, in IS-IS if you don't have neighbors that in turn means no routes either. Hence looking for neighbors is a good place to start your IS-IS troubleshooting. Use the following commands to assist with shooting other IS-IS troubles:
show ip protocols
show protocols
show ip route
clear isis *
log-adjacency-changes
show clns neighbors [detail] to verify the status of adjacencies
show clns interface to verify the configuration of the interface
show isis database to list the packets in the link-state database
show isis topology to list the system IDs of known IS-IS routers
show isis spf-log to display shortest path first events
debug isis adj-packets
debug isis update-packets
debug isis spf-events
Common IS-IS issues include misconfiguration, mismatched Level 1/Level 2 interfaces, area misconfiguration, and duplicate system IDs. Always check your neighbors and your logs. If you have turned on log-adjacency-changes remember to do a show logging to see the results. You may need to increase your logging buffer as well.
Now that IS-IS is working and you have full connectivity via the serial link between r5 and r6, modify the ISDN configuration to use CHAP authentication as in Example 9-66.
Example 9-66. Configuring CHAP Authentication
r5(config)#interface bri0 r5(config-if)#encap ppp r5(config-if)#ppp authentication chap r5(config-if)#username r6 pass donna r5(config)#end r6(config)#interface bri0 r6(config-if)#encap ppp r6(config-if)#ppp authentication chap r6(config-if)#username r5 pass donna r6(config)#end r5#copy running-config startup-config r6#copy running-config startup-config |
Ping to verify that your new configuration is operational. Shut down or remove the serial cable between r5 and r6 to make sure that the ISDN connection is used. Alternatively, configure the ISDN connection as an automatic backup to the serial link. If you want to look at the CHAP challenge again, issue the debug ppp authentication command.
Trouble Ticket 6 Solution
Thus far you have worked with the ISDN D channel for call setup and signaling and the one B channel for data traffic. Example 9-67 illustrates how to automatically bring up the second B channel if the load on the first one is more than 10 percent. To see the effect, repeat the exercise with the load at five percent if you experience problems.
Example 9-67. Configuring the dialer load-threshold
r5#clear dialer r5#clear counters r5#configure terminal r5(config)#interface bri0 r5(config-if)#dialer load-threshold 25 either r5(config-if)#end r5#copy running-config startup-config r6#clear dialer r6#clear counters r6(config)#interface bri0 r6(config-if)#dialer load-threshold 25 either r6(config-if)#end r6#copy running-config startup-config |
Now that things are configured, test it as in Example 9-68.
Example 9-68. Bringing Up the Second B Channel
r5#ping Protocol [ip]: Target IP address: 6.6.6.6 Repeat count [5]: 100 Datagram size [100]: 1500 Timeout in seconds [2]: Extended commands [n]: y Source address or interface: Type of service [0]: Set DF bit in IP header? [no]: Validate reply data? [no]: Data pattern [0xABCD]: Loose, Strict, Record, Timestamp, Verbose[none]: verbose Loose, Strict, Record, Timestamp, Verbose[V]: Sweep range of sizes [n]: y Sweep min size [36]: Sweep max size [18024]: Sweep interval [1]: Type escape sequence to abort. Sending 1798900, [36..18024]-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds: Request 0 timed out (size 36) Reply to request 1 (20 ms) (size 37) ... Reply to request 26 (28 ms) (size 62) Dec 24 05:49:46: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state to up Reply to request 27 (32 ms) (size 63) ... Reply to request 127 (52 ms) (size 163) Reply to request 128 (52 ms) (size 164) Dec 24 05:49:51: %ISDN-6-CONNECT: Interface BRI0:1 is now connected to 8358661 r6 ... Reply to request 425 (124 ms) (size 461) Dec 24 05:50:19: BR0 DDR: rotary group to 8358661 overloaded (27) Dec 24 05:50:19: BR0 DDR: Attempting to dial 8358661 Dec 24 05:50:20: %LINK-3-UPDOWN: Interface BRI0:2, changed state to up Dec 24 05:50:20: %ISDN-6-CONNECT: Interface BRI0:1 is now connected to 8358661 r6 ... Dec 24 05:50:20: BR0:2 DDR: dialer protocol up Dec 24 05:50:21: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:2, changed state to up Reply to request 434 (128 ms) (size 470) ... Reply to request 440 (128 ms) (size 476) Dec 24 05:50:21: BR0 DDR: rotary group to 8358661 underloaded (14), starting load activity timer ... Dec 24 05:50:26: %ISDN-6-CONNECT: Interface BRI0:2 is now connected to 8358661 r6 ... |
As you can see in Example 9-68, extended ping is a powerful traffic generator for getting the threshold to a level to bring up the second B channel. A ping sweep of 36 to 1500 bytes is a good initial test when installing or troubleshooting devices. Over 1500 bytes doesn't buy you a whole lot, because the MTU size is 1500, but small sizes are good for latency issues. Sending 1500 bytes with a data pattern of all 1s or all 0s is a good practical test, too. The Windows default is 32 bytes, but you can use the ping -l parameter to adjust this on the PC. On the other hand, the very large ping size buys me a lot in this ticket. The packets are over 1500 bytes, so they must be fragmented, and I want to hurry up and get a load on the line to bring up the needed second B channel.
I stopped the output instead of waiting for it to finish. Verify that the second B channel was truly brought up as in Example 9-69.
Example 9-69. Verifying the Second B Channel
r5#show dialer Dial on demand events debugging is on BRI0 - dialer type = ISDN Dial String Successes Failures Last called Last status 8358663 0 0 never - 8358661 2 0 00:00:44 successful 0 incoming call(s) have been screened. 0 incoming call(s) rejected for callback. BRI0:1 - dialer type = ISDN Idle timer (55 secs), Fast idle timer (20 secs) Wait for carrier (30 secs), Re-enable (15 secs) Dialer state is data link layer up Dial reason: ip (s=192.168.9.22, d=6.6.6.6) Time until disconnect 10 secs Connected to 8358661 (r6) BRI0:2 - dialer type = ISDN Idle timer (55 secs), Fast idle timer (20 secs) Wait for carrier (30 secs), Re-enable (15 secs) Dialer state is data link layer up Dial reason: Dialing on overload Time until disconnect 51 secs Connected to 8358661 (r6) r5#show interface bri0 1 2 BRI0:1 is up, line protocol is up Hardware is BRI MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation PPP, loopback not set, keepalive set (10 sec) Time to interface disconnect: idle 00:00:02 LCP Open Open: IPCP, CDPCP Last input 00:00:03, output 00:00:03, output hang never Last clearing of "show interface" counters 00:02:19 Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/1/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 447 packets input, 105642 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 447 packets output, 105642 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets 0 output buffer failures, 0 output buffers swapped out 1 carrier transitions BRI0:2 is up, line protocol is up Hardware is BRI MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec, rely 255/255, load 27/255 Encapsulation PPP, loopback not set, keepalive set (10 sec) Time to interface disconnect: idle 00:00:41 LCP Open Open: IPCP, CDPCP Last input 00:00:05, output 00:00:05, output hang never Dec 24 05:51:15: BR0:1 DDR: idle timeout Dec 24 05:51:15: BR0:1 DDR: disconnecting call Dec 24 05:51:15: %ISDN-6-CONNECT: Interface BRI0:2 is now connected to 8358661 r6 Dec 24 05:51:15: %ISDN-6-DISCONNECT: Interface BRI0:1 disconnected from 8358661 r6, call |
Both B channels were in fact up but are disconnecting due to the idle timeout.
Because the load went up to about 27, the second B channel came up. 255/255 is 100-percent load. For anything less than 255, you can divide the numerator by the denominator to get the load as a percentage. You set the dialer threshold to 25, which is about .10 times 255 or 25/255.
Compare your final saved fixed configurations to the chapter 9 ending configs file. Update your documentation and fix anything that is broken. You have completed the chapter Trouble Tickets when you feel comfortable with the tasks assigned and the various scenarios throughout the chapter. Review or experiment in the areas where you need more help. Understanding and troubleshooting in a lab is certainly the basis for configuring devices in the real world. Check your understanding with the chapter review questions.