You want to check on the dialer status of a router.
Here are some useful commands for looking at the status of a dial backup link. For dial backup that uses the floating static or dialer watch type configurations, you can use the show dialer command:
Router1#show dialer
For dial configurations that use the backup interface configuration, you can use the show backup command:
Router1#show backup
And, for backup configurations that use ISDN, you can get some additional information from the show isdn status, show isdn active, and show isdn history commands:
Router1#show isdn status Router1#show isdn active Router1#show isdn history
The show dialer command provides a lot of useful information about existing dial sessions as well as some historical statistics:
Router1#show dialer BRI0 - dialer type = ISDN Dial String Successes Failures Last DNIS Last status 0 incoming call(s) have been screened. 0 incoming call(s) rejected for callback. BRI0:1 - dialer type = ISDN Idle timer (300 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=10.1.99.55, d=224.0.0.10) Interface bound to profile Dialer1 Current call connected 00:03:18 Connected to 95551212 (dialhost) BRI0:2 - dialer type = ISDN Idle timer (120 secs), Fast idle timer (20 secs) Wait for carrier (30 secs), Re-enable (15 secs) Dialer state is idle Dialer1 - dialer type = DIALER PROFILE Load threshold for dialing additional calls is 100 Idle timer (300 secs), Fast idle timer (20 secs) Wait for carrier (30 secs), Re-enable (15 secs) Dialer state is data link layer up Number of active calls = 1 Number of active circuit switched calls = 0 Dial String Successes Failures Last DNIS Last status 95551212 2 0 00:03:19 successful Default Router1#
There is a lot of useful information in this output. First, notice that there is an active dial session on the first B-channel of this ISDN BRI interface, BRI0:1. It has been connected for a little more than three minutes, and you can see the dial string that represents the remote telephone number. The second ISDN B-channel, BRI0:2, is not connected, presumably because the router has yet not seen the minimum traffic threshold that we specified for bringing up the second channel, or perhaps because it isn't configured for PPP multilink.
But there is another extremely important piece of information here. Note the line marked "Dial reason," which shows the source and destination IP addresses of the packet that originally caused the router to start the dial session. In this case, the source IP address is 10.1.99.55, which is the IP address of the dial interface itself. The destination IP address is 224.0.0.10, which is extremely interesting because this is the multicast IP address that EIGRP uses to talk between routers. This is fine if we intended for this dial connection to remain up all the time. However, if this router was supposed to only dial when a primary link failed, looking at this output should tell you that the dialer list configuration is wrong.
The bottom of the display includes some historical information about each of the configured dial strings, and lists how often the router has been able to connect successfully using each string. In this case there is only one dial string, but if there were several, they would all appear with their respective totals.
The show backup command is only useful when you use the backup interface configuration, which is discussed in Recipe 13.4:
Router1#show backup Primary Interface Secondary Interface Status ----------------- ------------------- ------ Serial0/0 BRI0/0 active backup
In this case the interface BRI0/0 is operating as an active backup for the primary interface, Serial0/0. If the primary interface is working properly, the Status column will say "normal operation." In this case, the backup interface will go into a standby mode:
Router1#show int bri0/0
BRI0 is standby mode, line protocol is down
Hardware is BRI
Internet address is 10.1.99.55/24
MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, loopback not set
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/0/16 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 48 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 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
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 7 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
Router1#
If you are using ISDN for dial backup in any of the configurations discussed, you can get other useful information through the various show isdn commands:
Router1#show isdn status
Global ISDN Switchtype = basic-ni
ISDN BRI0/0 interface
dsl 0, interface ISDN Switchtype = basic-ni
Layer 1 Status:
ACTIVE
Layer 2 Status:
TEI = 89, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED
TEI = 90, Ces = 2, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED
TEI 89, ces = 1, state = 8(established)
spid1 configured, spid1 sent, spid1 valid
Endpoint ID Info: epsf = 0, usid = 70, tid = 1
TEI 90, ces = 2, state = 8(established)
spid2 configured, spid2 sent, spid2 valid
Endpoint ID Info: epsf = 0, usid = 71, tid = 2
Layer 3 Status:
1 Active Layer 3 Call(s)
Activated dsl 0 CCBs = 1
CCB:callid=801A, sapi=0, ces=1, B-chan=1, calltype=DATA
The Free Channel Mask: 0x80000002
Total Allocated ISDN CCBs = 2
Router1#
This example shows a single active call on one of the ISDN B-channels. Another useful piece of information is provided by the lines that say that each SPID was configured, sent, and considered "valid" by the switch. In this case, we were connected to a basic-ni type switch, which requires us to manually configure SPIDs. So it is important to check that the switch accepted these values.
If there are active calls, the output of show isdn active can also be useful:
Router1#show isdn active
--------------------------------------------------------------------------------
ISDN ACTIVE CALLS
--------------------------------------------------------------------------------
History table has a maximum of 100 entries.
History table data is retained for a maximum of 15 Minutes.
--------------------------------------------------------------------------------
Call Calling Called Remote Seconds Seconds Seconds Charges
Type Number Number Name Used Left Idle Units/Currency
--------------------------------------------------------------------------------
Out +95551212 dialhost 207 0 0
--------------------------------------------------------------------------------
Router1#
Here you can see that there is a single active call. This output also tells you exactly how long the call has been connected, and whether it was an in or outbound connection. You can also get some potentially useful historical information about previous calls from the show isdn history command:
Router1#show isdn history
--------------------------------------------------------------------------------
ISDN CALL HISTORY
--------------------------------------------------------------------------------
History table has a maximum of 100 entries.
History table data is retained for a maximum of 15 Minutes.
--------------------------------------------------------------------------------
Call Calling Called Remote Seconds Seconds Seconds Charges
Type Number Number Name Used Left Idle Units/Currency
--------------------------------------------------------------------------------
Out Failed
Out +95551212 dialhost 20 0
Out +95551212 dialhost 219 0 0
--------------------------------------------------------------------------------
Router1#
This router has attempted to make three outbound calls. The first call failed, the second lasted 20 seconds before disconnecting, and the third lasted 219 seconds. This output can be particularly useful if you think that your router might be dialing too often, or that it might be frequently dialing and dropping calls. You can also look in the router's logging buffer for log messages. By default, every time the router dials, it will generate at least one log message. Please refer to Chapter 18 for more information on logging.
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