CCIE Practical Studies, Volume I

Lab 33: Configuring HSRP, Tracking, and Asymetrical Routing ”Part II

Lab Walkthrough

After completing the physical installation and the Frame Relay switch configuration, you should establish IP connectivity among all the routers. Example 16-7 lists the Frame Relay configuration used in this lab.

Example 16-7 Frame Relay Switch Configuration

hostname frame_switch ! frame-relay switching ! <<<text omitted>>> ! interface Serial0 no ip address encapsulation frame-relay no fair-queue clockrate 148000 frame-relay intf-type dce frame-relay route 131 interface Serial1 31 frame-relay route 121 interface Serial3 21 ! interface Serial1 no ip address encapsulation frame-relay clockrate 148000 frame-relay intf-type dce frame-relay route 31 interface Serial0 131 ! interface Serial2 no ip address shutdown ! interface Serial3 no ip address encapsulation frame-relay clockrate 64000 frame-relay intf-type dce frame-relay route 21 interface Serial0 121 !

Beginning with the headquarters_co router, configure the IP addresses of Ethernet and serial interfaces. Because you are configuring a multipoint Frame Relay network, you should use frame-relay map statements. Make the map statements point to the IP address of charlie_1 and charlie_2, like the following:

frame-relay map ip 25.100.10.2 121 broadcast frame-relay map ip 25.100.10.3 131 broadcast

Next, configure RIP Version 2 (RIP-2) as the routing protocol, as done in Example 16-8. RIP-2 is configured by adding the version 2 argument under the routing protocol. In this model, you will also added the distance argument. The distance argument will point a primary route to charlie_1; charlie_2 has an administrative distance of 125, which is 5 higher than a normal RIP distance of 120. This will force all outbound traffic to first go to the charlie_1 router, and the network to have asymetrical routing.

Example 16-8 RIP-2 Configuration

router rip version 2 network 25.0.0.0 distance 125 0.0.0.3 255.255.255.0

The same set of commands will be needed on all routers in the 4th Army Com Net that are not running Cisco IOS Software Release 12.0. Next, configure the serial and Ethernet interfaces to send and receive RIP-2 updates by using the following commands:

ip rip send version 2 ip rip receive version 2

Again, these same statements will be used on all the routers in 4th Army Com Net.

When you are finished with the configuration for the headquarters_co router, it will look like Example 16-9.

Example 16-9 Configuration of the headquarters_co Router

hostname headquarters_co ! interface Ethernet0 ip address 25.100.6.1 255.255.255.0 ip rip send version 2 ip rip receive version 2 media-type 10BaseT ! interface Serial0 ip address 25.100.10.1 255.255.255.0 ip rip send version 2 ip rip receive version 2 encapsulation frame-relay no ip mroute-cache frame-relay map ip 25.100.10.2 121 broadcast frame-relay map ip 25.100.10.3 131 broadcast ! <<<<text omitted>>> ! router rip version 2 network 25.0.0.0 distance 125 0.0.0.3 255.255.255.0 ! headquarters_co#

Moving on to the IP configuration of the Charlie Company routers, you should begin by adding IP addresses to the Ethernet and serial interfaces of each router. As mentioned previously, each router will also need to be configured for RIP-2. Follow the same steps as previously noted for the RIP-2 configuration. Because this is a multipoint Frame Relay network, you will also need to add frame-relay map statements. When you are finished with the IP configuration for each router, the configurations should resemble Example 16-10.

Example 16-10 charlie_1 and charlie_2 IP Configurations

hostname charlie_1 ! <<<text omitted ! interface Ethernet0 ip address 25.100.61.1 255.255.255.0 no ip directed-broadcast ip rip send version 2 ip rip receive version 2 ! interface Serial0 ip address 25.100.10.2 255.255.255.0 no ip directed-broadcast ip rip send version 2 ip rip receive version 2 encapsulation frame-relay no ip mroute-cache frame-relay map ip 25.100.10.1 21 broadcast frame-relay map ip 25.100.10.3 21 broadcast frame-relay lmi-type cisco ! <<<text omitted>>> ! router rip version 2 network 25.0.0.0 ! <<<text omitted>>> charlie_1# _________________________________________________________________ hostname charlie_2 ! interface Ethernet0 ip address 25.100.61.2 255.255.255.0 ip rip send version 2 ip rip receive version 2 ! interface Serial0 ip address 25.100.10.3 255.255.255.0 ip rip send version 2 ip rip receive version 2 encapsulation frame-relay frame-relay map ip 25.100.10.1 31 broadcast frame-relay map ip 25.100.10.2 31 broadcast ! <<<text omitted>>> router rip version 2 network 25.0.0.0 !

After establishing end-to-end IP connectivity, you can begin to configure HSRP. Following the steps for HSRP, you must first define the HSRP or virtual router IP address. All the workstations at Charlie Company point to a default gateway address of 25.100.61.3. Therefore, this will be your HSRP address. Each router will need the preempt and the priority statements as well.

Because charlie_1 will be the primary router, you should set its priority above the default of 100. Before setting the priority, take into consideration the circumstance at which you will want this router to not be the primary. In this model, you want charlie_1 to be the primary until the link fails. If you set the priority of charlie_1 to 105 and use the default tracking cost of the serial interfaces on charlie_1 and charlie_2 of 10, this will put the priority at 95 upon the loss of a serial link. Therefore, you will need to set the priority of charlie_2 to greater then 95 but less then 105. Example 16-11 demonstrates the configuration of the charlie_1 router.

Example 16-11 Configuration of charlie_1 Router for HSRP

charlie_1# conf t Enter configuration commands, one per line. End with CNTL/Z. charlie_1(config )#interface ethernet 0 charlie_1(config-if)# standby 1 ip 25.100.61.3 charlie_1(config-if)# standby 1 preempt charlie_1(config-if)# standby 1 priority 105 04:08:11: %STANDBY-6-STATECHANGE: Standby: 1: Ethernet0 state Speak -> Stan dby 04:08:11: %STANDBY-6-STATECHANGE: Standby: 1: Ethernet0 state Standby -> Active charlie_1(config-if)# standby 1 track serial 0

When configuring HSRP, a state change message will be sent when HSRP becomes active. When this is complete, verify the HSRP configuration with the show standby ethernet 0 command, as demonstrated in Example 16-12. Look for the local state to be "active," and make sure that the active router is "local." Also ensure that the host standby IP address is the one that you configured.

Example 16-12 Status of the Primary Router

charlie_1# show standby ethernet 0 Ethernet0 - Group 1 Local state is Active, priority 105, may preempt Hellotime 3 holdtime 10 Next hello sent in 00:00:00.678 Hot standby IP address is 25.100.61.3 configured Active router is local Standby router is 25.100.61.2 expired Standby virtual mac address is 0000.0c07.ac01 Tracking interface states for 1 interface, 1 up: Up Serial0 charlie_1#

The configuration of the charlie_2 router will be identical to the configuration of the charlie_1 router, except for the priority, which can be left at the default of 100. Setting the priority at 101 is still preferred, to ensure that this router is second only to the primary. This also helps to break any possible "tie-breakers" with new routers that might be added to the HSRP group in the future. When this is complete, verify HSRP on charlie_2 with the show standby Ethernet 0 command, as listed in Example 16-13.

Example 16-13 Status of the Standby Router

charlie_2# show standby ethernet 0 Ethernet0 - Group 1 Local state is Standby, priority 101, may preempt Hellotime 3 holdtime 10 Next hello sent in 00:00:01.336 Hot standby IP address is 25.100.61.3 configured Active router is 25.100.61.1 expires in 00:00:09 Standby router is local Tracking interface states for 1 interface, 1 up: Up Serial0 charlie_2#

In this example, you want to verify that the local state is standby and that it may preempt, or take over as the active router, if priority warrants it. Example 16-14 shows the HSRP configuration for both Ethernet interfaces on charlie_1 and charlie_2.

Example 16-14 HSRP Configurations for charlie_1 and charlie_2

charlie_1# interface Ethernet0 ip address 25.100.61.1 255.255.255.0 no ip redirects no ip directed-broadcast ip rip send version 2 ip rip receive version 2 standby 1 priority 105 standby 1 preempt standby 1 ip 25.100.61.3 standby 1 track Serial0 _________________________________________________________________ charlie_2# interface Ethernet0 ip address 25.100.61.2 255.255.255.0 no ip redirects ip rip send version 2 ip rip receive version 2 standby 1 priority 101 standby 1 preempt standby 1 ip 25.100.61.3 standby 1 track Serial0 !

To test the HSRP configuration for functionality, attach an IP-based workstation, as shown in Figure 16-2. Make sure that the default gateway on the workstation is pointing to 25.100.61.3. This workstation should be capable of ping ing the IP address of the E0 port of the headquarters_co router or the headquarters servers, if you have them configured. To test the failover process, go to the frame switch and disable the serial interface attached to the charlie_1 router. HSRP will note that the interface is down and will subtract the cost associated with the interface ”in this case, the default of 10. This will put the priority of charlie_1 at 95, less than charlie_2, so charlie_2 should be active. You can verify the failover by performing traceroute functions on the workstations and by using the show standby interface command. Example 16-15 lists the show standby interface output on charlie_2 after you have downed the frame switch serial interface attached to charlie_1. Note the state change from standby to active.

Example 16-15 show standby Command Output After Failover

charlie_2# show standby ethernet 0 Ethernet0 - Group 1 Local state is Active, priority 101, may preempt Hellotime 3 holdtime 10 Next hello sent in 00:00:00.952 Hot standby IP address is 25.100.61.3 configured Active router is local Standby router is 25.100.61.1 expires in 00:00:07 Tracking interface states for 1 interface, 1 up: Up Serial0 charlie_2#

Also ensure that IP routing is working by issuing test ping s from the workstations and by looking at the routing table of headquarters_co router. Example 16-16 lists the routing table of headquarters_co, before and after the failover. It first shows RIP updates coming from 25.100.10.2, the primary router. After failover, the routing updates start to come from 25.100.10.3, with an administrative distance of 125.

Example 16-16 IP Route Table Before and After Failover Tests

headquarters_co# show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP <<<text omitted>>> 25.0.0.0/24 is subnetted, 3 subnets R 25.100.61.0 [120/1] via 25.100.10.2, 00:00:01, Serial0 C 25.100.10.0 is directly connected, Serial0 C 25.100.6.0 is directly connected, Ethernet0 headquarters_co# ! AFTER WE DOWN THE FRAME INTERFACE WE HAVE THE FOLLOWING: headquarters_co# show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP <<<text omitted>>> Gateway of last resort is not set 25.0.0.0/24 is subnetted, 3 subnets R 25.100.61.0/24 is possibly down, routing via 25.100.10.2, Serial0 C 25.100.10.0 is directly connected, Serial0 C 25.100.6.0 is directly connected, Ethernet0 headquarters_co# headquarters_co# show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP <<<text omitted>>> Gateway of last resort is not set 25.0.0.0/24 is subnetted, 3 subnets R 25.100.61.0 [125/1] via 25.100.10.3, 00:00:17, Serial0 C 25.100.10.0 is directly connected, Serial0 C 25.100.6.0 is directly connected, Ethernet0 headquarters_co#

The time that it takes for RIP-2 to converge from the primary router to the backup router can be a few minutes. This leads to the optional part of the lab. To improve the design of the 4th Army Com Net, you could change the routing protocol from RIP-2 to EIGRP or OSPF. By switching the routing protocol, IP convergence can happen much quicker. This, in turn , better supports the functionality and purpose of HSRP.

In this model, you use EIGRP because the migration from RIP to EIGRP can be quite easy. The best way to migrate to EIGRP is simply to add the router eigrp command with an autonomous system and network address. Because the administrative distance of EIGRP is less than that of RIP, the routing table will automatically converge from RIP to EIGRP, as shown in Example 16-17.

Example 16-17 IP Routing Table of headquarters_co Router on EIGRP

headquarters_co# 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 <<<text omitted>>> Gateway of last resort is not set 25.0.0.0/24 is subnetted, 3 subnets D 25.100.61.0 [90/2195456] via 25.100.10.2, 00:00:02, Serial0 C 25.100.10.0 is directly connected, Serial0 C 25.100.6.0 is directly connected, Ethernet0 headquarters_co#

To influence the routes advertised by EIGRP, add a DELAY to the Ethernet segment of charlie_2. This way, when EIGRP reports that route to headquarters_co, it will be weighted. This then will cause EIGRP to have a preferred route to the subnet 25.100.61.0/24, through the charlie_1 router. The delay should be added to the Ethernet interface instead of the serial interface because traffic destined for the headquarters master server from charlie_2 should leave through the serial interface. If the delay is put there, EIGRP will want to route this traffic through the Ethernet port to charlie_1 first. When your EIGRP configuration is complete, remove the RIP portions of the configuration with the no router rip command. This command will remove all RIP- related statements.