IntrodUCtion
In this configuration, we have two Catalyst 6509 switches, each with two Multilayer Switch Feature Cards (MSFCs), for a total of four routers. Our strategy is to have the MSFC-a1 in the diagram below route for odd virtual LANs (VLANs), as the PRimary router, and MSFC-b1 to route odd VLANs as the backup router. For even VLANs, we want MSFC-b2 to be the primary router and MSFC-a2 to be the backup router.
Note: The backup routers (MSFCs) don't have a standby priority eXPlicitly assigned so they default to priority 100. We add the standby preempt statement so that if the primary router goes down and comes back up, it resumes the highest priority, or preempt control.
MSFC-a1配置信息：
msfc-a1#
!
hostname msfc-a1
!
!
interface Vlan1
ip address 1.1.1.2 255.255.0.0
standby 1 priority 110 preempt
standby 1 ip 1.1.1.1
!
interface Vlan3
ip address 3.1.1.2 255.255.0.0
standby 3 priority 110 preempt
standby 3 ip 3.1.1.1
!
!
end
MSFC-a2配置信息：
msfc-a2#
!
hostname msfc-a2
!
!
interface Vlan2
ip address 2.1.1.3 255.255.0.0
standby 2 ip 2.1.1.1
!
interface Vlan4
ip address 4.1.1.3 255.255.0.0
standby 4 ip 4.1.1.1
!
!
end
MSFC-b1配置信息：
msfc-b1#
!
hostname msfc-b1
!
!
interface Vlan1
ip address 1.1.1.3 255.255.0.0
standby 1 ip 1.1.1.1
!
interface Vlan3
ip address 3.1.1.3 255.255.0.0
standby 3 ip 3.1.1.1
!
!
end
MSFC-b2配置信息：
msfc-b2#
!
hostname msfc-b2
!
!
interface Vlan2
ip address 2.1.1.2 255.255.0.0
standby 2 priority 110 preempt
standby 2 ip 2.1.1.1
!
interface Vlan4
ip address 4.1.1.2 255.255.0.0
standby 4 priority 110 preempt
standby 4 ip 4.1.1.1
!
!
!
end
相关命令与讲解如下：
debug and show Commands
Verify that HSRP is working by using the show standby command. In the output below, MSFC-a1 sees its backup router as "Standby router 3.1.1.3."
msfc-a1#show standby
Vlan1 - Group 1
Local state is Active, priority 110, may preempt
Hellotime 3 holdtime 10
Next hello sent in 00:00:01.588
Hot standby IP address is 1.1.1.1 configured
Active router is local
Standby router is 1.1.1.3 expires in 00:00:08
Standby virtual mac address is 0000.0c07.ac01
Vlan3 - Group 3
Local state is Active, priority 110, may preempt
Hellotime 3 holdtime 10
Next hello sent in 00:00:02.092
Hot standby IP address is 3.1.1.1 configured
Active router is local
Standby router is 3.1.1.3 expires in 00:00:08
Standby virtual mac address is 0000.0c07.ac03
When we issue the show standby command from MSFC-b1, we see that for VLAN 1 and 3, MSFC-b1 is the backup or standby router: "Local state is Standby, priority 100." The active router is 1.1.1.2, or MSFC-a1, which has priority 110. Since 110 is greater than 100, MSFC-a1 is the active router.
msfc-b1#show standby
Vlan1 - Group 1
Local state is Standby, priority 100
Hellotime 3 holdtime 10
Next hello sent in 00:00:01.440
Hot standby IP address is 1.1.1.1 configured
Active router is 1.1.1.2 expires in 00:00:09
Standby router is local
Standby virtual mac address is 0000.0c07.ac01
Vlan3 - Group 3
Local state is Standby, priority 100
Hellotime 3 holdtime 10
Next hello sent in 00:00:01.478
Hot standby IP address is 3.1.1.1 configured
Active router is 3.1.1.2 expires in 00:00:09
Standby router is local
Standby virtual mac address is 0000.0c07.ac03
When HSRP isn't configured correctly, you see show standby output similar to that below, which shows MSFC-b2 doesn't see its HSRP partner.
msfc-b2#show standby
Vlan2 - Group 2
Local state is Active, priority 110, may preempt
Hellotime 3 holdtime 10
Next hello sent in 00:00:02.904
Hot standby IP address is 2.1.1.1 configured
Active router is local
Standby router is unknown expired
When you see this output, first check that the configuration is correct. Then verify that all the VLANs are passing through the trunk between the two switches. In the output below, VLANs 1 through 4 are passing through correctly.
Switch (enable)#show trunk 8/1
Port Mode Encapsulation Status Native vlan
-------- ----------- ------------- ------------ -----------
8/1 desirable n-isl trunking 1
Port Vlans allowed on trunk
----------------------------------------------------------------
8/1 1-1005
Port Vlans allowed and active in management domain
----------------------------------------------------------------
8/1 1-4
Port Vlans in spanning tree forwarding state and not pruned
----------------------------------------------------------------
8/1 1-4
If you're still running into issues, ensure that the virtual VLAN interfaces are up by issuing the show interface vlan command.
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