5.2 Optimizing HSRP
5.2.1 Describing HSRP Optimization Options
The options illustrated in Figures 
and 
make it possible to optimize HSRP operation in the campus network.
Each standby group has its own active and standby routers. The network administrator can assign a priority value to each router in a standby group, allowing the administrator to influence the active and standby router selection. 
To set the priority value of a router (default is 100), enter this command in interface configuration mode:
Switch(config-if)#standby group-number priority priority-value
Figure 
describes the variables for the standby command.
During the election process, the router with the highest priority in an HSRP group becomes the active router. In the case of a tie, the router with the highest configured IP address is chosen.
To reinstate the default standby priority value, use the no standby priority command.
The following example states that interface VLAN10 has a priority value of 150 in HSRP group 1. If this priority value is the highest number in that HSRP group, the routing device on which this interface resides is the active router for that group.
Switch#show running-config
Building configuration...
Current configuration:
!
The standby router automatically assumes the active router role when the active router fails or is removed from service. This new active router remains the forwarding router, even if a former active router with a higher priority regains service in the network.
A former active router can be configured to resume the forwarding router role from a router with a lower priority by using the following command in interface configuration mode:
Switch(config-if)#standby [group-number] preempt [{delay} [minimum delay] [sync delay]]
When the standby preempt command is issued, the interface changes to the appropriate state. 
Note:
If the routers do not have preempt configured, a router that boots up significantly faster than the others in the standby group becomes the active router, regardless of the configured priority.
To remove the interface from preemptive status, use the no standby group preempt command.
The following example states that interface VLAN10 is configured to resume its role as the active router in HSRP group 1, assuming that interface VLAN10 on this router has the highest priority in that standby group.
Switch#show running-config
Building configuration...
Current configuration:
!
HSRP hello messages are transmitted constantly by the active and standby HSRP routers and during elections by all HSRP-enabled routers. The hello message contains the priority of the router, along with the hello time and hold time values. The hello time is the interval between the hello messages that the router sends. The hold time is the amount of time that the current hello message is considered valid. The default hello and hold times are 3 and 10 seconds, respectively, which means failover time could be as much as 10 seconds for clients to start communicating with the new default gateway. In some cases, this interval may be excessive for application support.
You can change the default values of the timers to milliseconds to accommodate subsecond failovers. Lowering the hello timer results in increased traffic for hello messages and should be used cautiously. 
The hold time should be at least three times the value of the hello time.
To change the timers, enter this command in interface configuration mode:
Switch(config-if)#standby group-number timers [msec] hellotime holdtime
Note:
Hello and dead timers intervals must be identical for all devices within an HSRP group.
Figure 
describes the command options.
To reinstate the default values, use the no standby group timers command.
In some situations, the status of an interface directly affects which router needs to become the active router. This is particularly true when each of the routers in an HSRP group has a different path to resources within the campus network.
In Figure 
, routers A and B reside in one building, and they each support a Gigabit Ethernet link to the other building. Router A has the higher priority and is the active forwarding router for standby group 1. Router B is the standby router for that group. Routers A and B are exchanging hello messages through their E0 interfaces.
The Gigabit Ethernet link between the active forwarding router for the standby group and the other building experiences a failure. 
If HSRP is not enabled, router A would detect the failed link and send an ICMP redirect to router B. However, when HSRP is enabled, ICMP redirects are disabled. Therefore, neither router A nor the virtual router sends an ICMP redirect. In addition, although the G1 interface on router A is no longer functional, router A still communicates hello messages out interface E0, indicating that router A is still the active router. Packets sent to the virtual router for forwarding to headquarters may not be routed.
It is possible that a dynamic routing protocol (if in use) would detect the link failure and then update the routing tables of the routers. However, traffic would then be sent by hosts to the active HSRP router and forwarded back across the Ethernet segment to the standby HSRP router where the functional Gigabit link would be used.
Interface tracking enables the priority of a standby group router to be automatically adjusted based on the availability of that router’s interfaces. When a tracked interface becomes unavailable, the HSRP priority of the router is decreased. When properly configured, the HSRP tracking feature ensures that a router with an unavailable key interface relinquishes the active router role.
In this example, the E0 interface on router A tracks the G1 interface. If the link between the G1 interface and the other building fails, the router automatically decrements the priority on the E0 interface and stops transmitting hello messages out that interface. Router B assumes the active router role when no hello messages are detected for the hold time period. The hello packet has a field that indicates the current priority of the HSRP-enabled interface. Router A changes this field to indicate its priority for subsequent hellos.
To configure HSRP tracking, enter the command in Figure 
in interface configuration mode.
To disable interface tracking, use the no standby group track command.
The command to configure HSRP tracking on a multilayer switch is the same as on the external router, except that the interface type can be identified as a switch virtual interface or as a physical interface.
Multiple tracking statements may be applied to an interface, which is useful if the intent is for the currently active HSRP interface to relinquish its status only when two (or more) tracked interfaces fail।
5.2.2 Tuning HSRP Operations
You can adjust HSRP timers to tune the performance of HSRP on distribution devices, thereby increasing their resilience and reliability in routing packets off the local VLAN.
You can set the HSRP hello and hold times to millisecond values so that HSRP failover occurs in less than 1 second. For example:
Switch(config-if)#standby 1 timers msec 200 msec 750
Remember that the lower the hello timer is, the greater the hello traffic.
Preemption is an important feature of HSRP, because it allows the primary router to resume the active role when the router comes back online after a failure or maintenance event. Preemption forces a predictable routing path for the VLAN during normal operations and ensures that the Layer 3 forwarding path for a VLAN parallels the Layer 2 Spanning Tree Protocol (STP) forwarding path whenever possible.
You should always use preemption when tracking interfaces. In the previous example, when the Gigabit link came back up, router A’s priority would increase, but without preemption, it would not become the HSRP active router until router B had a state change.
When a preempting distribution switch is rebooted, HSRP preempt communication should not begin until the distribution switch has established full connectivity to the rest of the network. This allows routing protocol convergence to occur more quickly once the preferred router is in an active state. To accomplish this, measure the system boot time and set the HSRP preempt delay to a value 50 percent greater than the boot time. This ensures that the primary distribution switch establishes full connectivity to the network before HSRP communication occurs.
For example, if the boot time for the distribution device is 120 seconds, the preempt configuration would be as follows:
standby 1 preempt
standby 1 preempt delay minimum 180
5.2.3 Describing Load Sharing
With a single HSRP group on a subnet, the active router is forwarding all the packets off that subnet while the standby router is not forwarding any packets. To facilitate load sharing, a single router may be a member of multiple HSRP groups on the same segment. Multiple standby groups further enable redundancy and load sharing. While a router is actively forwarding traffic for one HSRP group, the router can be in standby or listen state for another group. Each standby group emulates a single virtual router. There can be up to 255 standby groups on any LAN, but the maximum number of standby groups need be no more than the number of routers on a segment. In most cases, two standby groups are sufficient.
| CAUTION: Increasing the number of groups in which a router participates increases the load on the router, which can impact the router’s performance. |
In Figure , both router A and B are members of groups 1 and 2. Router A is the active forwarding router for group 1 and the standby router for group 2. Router B is the active forwarding router for group 2 and the standby router for group 1.
The following example shows how multiple HSRP groups can be configured on the same segment to facilitate load sharing. To be useful, half the hosts on the segment need to use 172.16.10.110 as a default gateway, while the other half need to use 172.16.10.120.
RouterA#show running-config
Building configuration...
Current configuration:
!
RouterB#show running-config
Building configuration...
Current configuration:
!
RouterA#show standby brief
P indicates configured to preempt.
|
Interface Grp Prio P State Active Standby Virtual IP
Vl10 1 150 Active local 172.16.10.33 172.16.10.110
Vl10 2 50 Standby 172.16.10.33 local 172.16.10.120
Routers can simultaneously provide redundant backup and perform load sharing across different IP subnets.
In Figure , two HSRP-enabled routers participate in two separate VLANs, using ISL or 802.1Q. Running HSRP over trunks allows users to configure redundancy among multiple routers that are configured as front ends for VLAN IP subnets. By configuring HSRP over trunks, users can eliminate situations in which a single point of failure causes traffic interruptions. This feature provides some improvement in overall networking resilience by providing load balancing and redundancy capabilities between subnets and VLANs.
For a VLAN, configure the same device to be both the spanning tree root and the HSRP active router. This approach ensures that the Layer 2 forwarding path leads directly to the Layer 3 active router, thereby achieving maximum load balancing efficiency on the routers and trunks.
A standby group, an IP address, and a single well-known MAC address with a unique group identifier should be allocated to the group for each VLAN. Although up to 255 standby groups can be configured, the number of group identifiers used should be kept to a minimum. If you are configuring two distribution layer switches, you typically need only two standby group identifiers.
The following example shows how multiple HSRP groups can be configured on two HSRP-enabled routers participating in two separate VLANs
RouterB#show running-config
Building configuration...
Current configuration:
!
5.2.4 HSRP Debug Commands
The commands in Figure are used to debug HSRP operations.
Figure describes the debug commands.
5.2.5 Debugging HSRP Operations
The Cisco IOS implementation of HSRP supports the debug command, which displays HSRP state changes and information regarding the transmission and receipt of HSRP packets. To enable HSRP debugging, enter the following command in privileged EXEC mode:
Switch#debug standby
Figure provides a description of debug standby fields.
| CAUTION: Because debugging output is assigned high priority in the CPU process, this command can render the system unusable. |
Example: Debugging with Two Active Routers
The example in Figure displays output on distribution router 1DSW1. Router 1DSW1 is also receiving an HSRP hello from 172.16.1.112 for the same VLAN and same virtual IP address but with a different standby group number. Hence, both routers are active for the same virtual IP address.
The debug standby command is being used to troubleshoot the problem. The standby group number is not consistent, so the two routers have not formed a standby group.
Example: Debugging Active Router Negotiation
This example displays the debug standby command output as the 1DSW1 router with IP address 172.16.1.111 initializes and negotiates for the role of active router.
*Mar 8 20:34:10.221: SB11: Vl11 Init: a/HSRP enabled
*Mar 8 20:34:10.221: SB11: Vl11 Init -> Listen
*Mar 8 20:34:20.221: SB11: Vl11 Listen: c/Active timer expired (unknown)
*Mar 8 20:34:20.221: SB11: Vl11 Listen -> Speak
*Mar 8 20:34:20.221: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 8 20:34:23.101: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 8 20:34:25.961: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 8 20:34:28.905: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 8 20:34:30.221: SB11: Vl11 Speak: d/Standby timer expired (unknown)
*Mar 8 20:34:30.221: SB11: Vl11 Standby router is local
*Mar 8 20:34:30.221: SB11: Vl11 Speak -> Standby
*Mar 8 20:34:30.221: SB11: Vl11 Hello out 172.16.11.111 Standby pri 100 ip 172.16.11.115
*Mar 8 20:34:30.221: SB11: Vl11 Standby: c/Active timer expired (unknown)
*Mar 8 20:34:30.221: SB11: Vl11 Active router is local
*Mar 8 20:34:30.221: SB11: Vl11 Standby router is unknown, was local
*Mar 8 20:34:30.221: SB11: Vl11 Standby -> Active
*Mar 8 20:34:30.221: %STANDBY-6-STATECHANGE: Vlan11 Group 11 state Standby -> Active
*Mar 8 20:34:30.221: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
To disable the debugging feature, use either the no debug standby or the no debug all command.
Example: Debugging First and Only Router on Subnet
Because 1DSW1 (172.16.11.111) is the only router on the subnet, and it is not configured for preempt, it goes through five HSRP states before becoming the active router. Notice that at Mar 8 20:34:10.221 the interface comes up, and 1DSW1 enters the listen state. The router stays in listen state for a hold time of 10 seconds. 1DSW1 then goes into speak state at Mar 8 20:34:20.221 for 10 seconds. When the router is speaking, it sends its state out every 3 seconds, according to its hello interval. After 10 seconds in speak state, the router has determined that there is no standby router and enters the standby state at Mar 8 20:34:30.221. The router has also determined that there is not an active router; therefore, it immediately enters active state at Mar 8 20:34:30.221. From that point on, the active router sends its active state hello message every 3 seconds. Because there are no other routers on this broadcast domain, no hellos are being received.
1DSW1(config)#interface vlan 11
1DSW1(config-if)#no shut
*Mar 8 20:34:08.925: %SYS-5-CONFIG_I: Configured from console by console
*Mar 8 20:34:10.213: %LINK-3-UPDOWN: Interface Vlan11, changed state to up
*Mar 8 20:34:10.221: SB: Vl11 Interface up
*Mar 8 20:34:10.221: SB11: Vl11 Init: a/HSRP enabled
*Mar 8 20:34:10.221: SB11: Vl11 Init -> Listen
*Mar 8 20:34:11.213: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan11, changed state to up
*Mar 8 20:34:20.221: SB11: Vl11 Listen: c/Active timer expired (unknown)
*Mar 8 20:34:20.221: SB11: Vl11 Listen -> Speak
*Mar 8 20:34:20.221: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 8 20:34:23.101: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 8 20:34:25.961: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 8 20:34:28.905: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 8 20:34:30.221: SB11: Vl11 Speak: d/Standby timer expired (unknown)
*Mar 8 20:34:30.221: SB11: Vl11 Standby router is local
*Mar 8 20:34:30.221: SB11: Vl11 Speak -> Standby
*Mar 8 20:34:30.221: SB11: Vl11 Hello out 172.16.11.111 Standby pri 100 ip 172.16.11.115
*Mar 8 20:34:30.221: SB11: Vl11 Standby: c/Active timer expired (unknown)
*Mar 8 20:34:30.221: SB11: Vl11 Active router is local
*Mar 8 20:34:30.221: SB11: Vl11 Standby router is unknown, was local
*Mar 8 20:34:30.221: SB11: Vl11 Standby -> Active
*Mar 8 20:34:30.221: %STANDBY-6-STATECHANGE: Vlan11 Group 11 state Standby -> Active
*Mar 8 20:34:30.221: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 8 20:34:33.085: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 8 20:34:36.025: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 8 20:34:38.925: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
Example: Router Without Preempt Coming Up
Router 1DSW1 (172.16.11.111) is configured with a priority of 100, which is higher than the priority of 50 of the current active router, 1DSW2 (172.16.11.112). Router 1DSW1 is not configured with preempt, so even though it has a higher priority, it does not immediately become the active router. After router 1DSW1 goes through the HSRP initialization states, it will come up as the standby router.
1DSW1(config)#interface vlan 11
1DSW1(config-if)#no shut
*Mar 1 00:12:16.871: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:16.871: SB11: Vl11 Active router is 172.16.11.112
*Mar 1 00:12:16.891: %SYS-5-CONFIG_I: Configured from console by console
*Mar 1 00:12:18.619: %LINK-3-UPDOWN: Interface Vlan11, changed state to up
*Mar 1 00:12:18.623: SB: Vl11 Interface up
*Mar 1 00:12:18.623: SB11: Vl11 Init: a/HSRP enabled
*Mar 1 00:12:18.623: SB11: Vl11 Init -> Listen
*Mar 1 00:12:19.619: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan11, changed state to up
*Mar 1 00:12:19.819: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:19.819: SB11: Vl11 Listen: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:22.815: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:22.815: SB11: Vl11 Listen: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:25.683: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:25.683: SB11: Vl11 Listen: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:28.623: SB11: Vl11 Listen: d/Standby timer expired (unknown)
*Mar 1 00:12:28.623: SB11: Vl11 Listen -> Speak
*Mar 1 00:12:28.623: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 1 00:12:28.659: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:28.659: SB11: Vl11 Speak: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:31.539: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:31.539: SB11: Vl11 Speak: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:31.575: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 1 00:12:34.491: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:34.491: SB11: Vl11 Speak: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:34.547: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 1 00:12:37.363: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:37.363: SB11: Vl11 Speak: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:37.495: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 1 00:12:38.623: SB11: Vl11 Speak: d/Standby timer expired (unknown)
*Mar 1 00:12:38.623: SB11: Vl11 Standby router is local
*Mar 1 00:12:38.623: SB11: Vl11 Speak -> Standby
*Mar 1 00:12:38.623: SB11: Vl11 Hello out 172.16.11.111 Standby pri 100 ip 172.16.11.115
*Mar 1 00:12:40.279: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:40.279: SB11: Vl11 Standby: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:41.551: SB11: Vl11 Hello out 172.16.11.111 Standby pri 100 ip 172.16.11.115
*Mar 1 00:12:43.191: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:43.191: SB11: Vl11 Standby: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:44.539: SB11: Vl11 Hello out 172.16.11.111 Standby pri 100 ip 172.16.11.115
*Mar 1 00:12:46.167: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:46.167: SB11: Vl11 Standby: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:47.415: SB11: Vl11 Hello out 172.16.11.111 Standby pri 100 ip 172.16.11.115
*Mar 1 00:12:49.119: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:49.119: SB11: Vl11 Standby: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:50.267: SB11: Vl11 Hello out 172.16.11.111 Standby pri 100 ip 172.16.11.115
Example: Router with Preempt Coming Up
Router 1DSW1 (172.16.11.11) is configured with a priority of 100, which is higher than the priority of the active router, 1DSW2 (172.16.11.112). 1DSW1 is also configured with preempt. At Mar 1 00:16:43.099, VLAN11 on 1DSW1 comes up and transitions into the listen state. At Mar 1 00:16:43.295, 1DSW1 receives a hello message from the active router (1DSW2). 1DSW1 determines that the active router has a lower priority. At Mar 1 00:16:43.295, 1DSW1 immediately sends out a coup message indicating that 1DSW1 is transitioning to the active router. 1DSW2 enters the speak state and eventually becomes the standby router.
1DSW1(config)#interface vlan 11
1DSW1(config-if)#no shut
*Mar 1 00:16:41.295: %SYS-5-CONFIG_I: Configured from console by console
*Mar 1 00:16:43.095: %LINK-3-UPDOWN: Interface Vlan11, changed state to up
*Mar 1 00:16:43.099: SB: Vl11 Interface up
*Mar 1 00:16:43.099: SB11: Vl11 Init: a/HSRP enabled
*Mar 1 00:16:43.099: SB11: Vl11 Init -> Listen
*Mar 1 00:16:43.295: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:16:43.295: SB11: Vl11 Active router is 172.16.11.112
*Mar 1 00:16:43.295: SB11: Vl11 Listen: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:16:43.295: SB11: Vl11 Active router is local, was 172.16.11.112
*Mar 1 00:16:43.295: SB11: Vl11 Coup out 172.16.11.111 Listen pri 100 ip 172.16.11.115
Mar 1 00:16:43.295
*Mar 1 00:16:43.299: %STANDBY-6-STATECHANGE: Vlan11 Group 11 state Listen -> Active
*Mar 1 00:16:43.299: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 1 00:16:43.303: SB11: Vl11 Hello in 172.16.11.112 Speak pri 50 ip 172.16.11.115
*Mar 1 00:16:44.095: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan11, changed state to up
*Mar 1 00:16:46.187: SB11: Vl11 Hello in 172.16.11.112 Speak pri 50 ip 172.16.11.115
*Mar 1 00:16:46.207: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 1 00:16:49.095: SB11: Vl11 Hello in 172.16.11.112 Speak pri 50 ip 172.16.11.115
*Mar 1 00:16:49.195: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 1 00:16:52.079: SB11: Vl11 Hello in 172.16.11.112 Speak pri 50 ip 172.16.11.115
*Mar 1 00:16:52.147: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 1 00:16:53.303: SB11: Vl11 Hello in 172.16.11.112 Standby pri 50 ip 172.16.11.115
*Mar 1 00:16:53.303: SB11: Vl11 Standby router is 172.16.11.112
*Mar 1 00:16:55.083: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 1 00:16:56.231: SB11: Vl11 Hello in 172.16.11.112 Standby pri 50 ip 172.16.11.115
*Mar 1 00:16:58.023: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 1 00:16:59.223: SB11: Vl11 Hello in 172.16.11.112 Standby pri 50 ip 172.16.11.115
*Mar 1 00:17:00.983: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 1 00:17:02.211: SB11: Vl11 Hello in 172.16.11.112 Standby pri 50 ip 172.16.11.115
*Mar 1 00:17:03.847: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
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