Dialer Watch is a vital part of your CCNA and CCNP studies, particularly for the BCRAN exam, but it's one of the most misunderstood technologies as well. To help you pass the CCNA and CCNP certification exams, here's a detailed look at Dialer Watch.
Laptop Battery Dialer Watch allows you to configure a route or routes as "watched" when the watched route leaves the routing table and there is no other valid route to that specific destination, the ISDN link will come up. In the following example, R1 and R2 are connected by both a Frame Relay cloud over the 172.12.123.0 /24 network and an ISDN cloud using the 172.12.12.0 /24 network. The routers are running OSPF over the Frame cloud, and R1 is advertising its loopback of 1.1.1.1/32 as well as an Ethernet segment, 10.1.1.0/24, via OSPF. R2 has both of these routes in its OSPF table, as shown below.
Before making a major investment into a computer certification, consider the steps that a vendor does or does not make to protect your investment. Computer certifications have helped me tremendously in building my IT career. By asking the right questions, and taking a hard look at your motives and plans before pursuing a given certification, they can do the same for you. Chris Bryant, 12933, is the owner of The Bryant Advantage ( //www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, Ultimate CCNP Study Packages, and CCNA CBT video training. Pass the CCNA exam, BSCI exam, and BCMSN exam with Chris Bryant, 12933!
Thinkpad R2#show ip route ospf
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Microsoft 1.0.0.0/32 is subnetted, 1 subnets
Interesting traffic brings the link up; by default, any traffic can cross the link once it's up; a lack of interesting traffic is what brings the link down. In Part II of this tutorial, we'll take a look at some common scenarios that make the ISDN link stay up, and what can be done about it. Chris Bryant, 12933, is the owner of The Bryant Advantage ( //www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, Ultimate CCNP Study Packages, and CCNA CBT video training. Pass the CCNA exam, BSCI exam, and BCMSN exam with Chris Bryant, 12933!
Laptop Computers O 1.1.1.1 [110/65] via 172.12.123.1, 00:00:07, Serial0
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Laptop Computer 10.0.0.0/24 is subnetted, 1 subnets
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Desktop Computer O 10.1.1.0 [110/128] via 172.12.123.1, 00:00:08, Serial0
Notebooks We want R2 to place a call to R1 if either the loopback or Ethernet networks leave R2's routing table, but we don't want to have to depend on interesting traffic. That dictates the use of Dialer Watch.
Lenovo First, configure the list of watched routes with dialer watch-list. Only one of the watched routes needs to leave the routing table for the ISDN link to come up. In this example, R2 will watch both routes from its OSPF routing table.
Hard Drive Be careful with this command. The entries here need to match exactly the routes and masks being watched. Dialer watch-lists use subnet masks, not wildcard masks.
Travelstar R2(config)#dialer watch-list 5 ip 10.1.1.0 255.255.255.0
Gateway R2(config)#dialer watch-list 5 ip 1.1.1.1 255.255.255.255
Laptop Parts Configure the dialer watch-group command on the BRI interface, AND frame map statements for the watched routes. As with dialer-list and dialer-group, the group number referenced in the dialer watch-group command must match the number assigned to the dialer watch-list.
Software The Dialer Watch configuration will not work without frame map statements for each watched route. I repeat this because this is the step a lot of people leave out.
Hard Drives R2(config)#interface bri0
Electronics R2(config-if)#dialer watch-group 5
Canon R2(config-if)# dialer map ip 1.1.1.1 255.255.255.255. name R1 5557777 broadcast
Desktop Pc R2(config-if)# dialer map ip 10.1.1.0 255.255.255.0 name R1 5557777 broadcast
Desktop Computers To test Dialer Watch, the Serial0 interface on R2 will be shut down. Since we're running OSPF, the route table will be updated almost immediately and the ISDN link should come up right after that.
Think Pad R2(config)#int s0
Repair R2(config-if)#shut
Data Recovery
01:12:47: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on Serial0 from FULL to DOWN, N
eighbor Down: Interface down or detached
Cisco
01:12:47: %LINK-3-UPDOWN: Interface BRI0:1, changed state to up
Keyboard 01:12:48: %SYS-5-CONFIG_I: Configured from console by console
Monitor 01:12:48: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state
to up
Desktop 01:12:49: %LINK-5-CHANGED: Interface Serial0, changed state to administratively
down
Infosys
01:12:50: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state
to down
Refurbished Laptops 01:12:53: %ISDN-6-CONNECT: Interface BRI0:1 is now connected to 5557777 R1
Wipro Within five seconds, the ISDN link is up. show dialer verifies that Dialer Watch is the reason the line was brought up.
Lap Top R2#show dialer
Refurbished BRI0 - dialer type = ISDN
Memory Dial String Successes Failures Last DNIS Last status
Intel 5557777 2 0 00:00:11 successful
As400 0 incoming call(s) have been screened.
Averatec 0 incoming call(s) rejected for callback.
Hardware BRI0:1 - dialer type = ISDN
Dual Xeon Idle timer (120 secs), Fast idle timer (20 secs)
Storage Wait for carrier (30 secs), Re-enable (15 secs)
Seagate Dialer state is data link layer up
Computer Sales Dial reason: Dialing on watched route loss
Computer Hardware Time until disconnect 108 secs
Printers Connected to 5557777 (R1)
A final note regarding Dialer Watch ... it will not work with RIP, but will with all our other dynamic IGPs (IGRP, EIGRP, OSPF).
Technology
Mainframe Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, Ultimate CCNP Study Packages, and CCNA CBT video training. Pass the CCNA exam ,BSCI exam , and BCMSN exam with Chris Bryant, CCIE #12933!
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