CCNP Switch - HotSpot - HSRP
- DSW1( Distribute switch 1) is the primary device for Vlan 101, 102, 105
- DSW2 ( Distribute switch 2) is the primary device for Vlan 103 and 104
During routine maintenance, it became necessary to shutdown G1/0/1 on DSW1. All other interface were up. During this time, DSW1 remained the active device for Vlan 102′s HSRP group. You have determined that there is an issue with the decrement value in the track command in Vlan 102′s HSRP group. What need to be done to make the group function properly?
Explicación: The question clearly stated that there was an issue with the decrement value in VLAN 102 so we should check VLAN 102 on both DSW1 and DSW2 switches first. Click on the PC Console1 and PC Console2 to access these switches then use the “show running-config” command on both switches
DSW1>enable DSW1#show running-config DSW2>enable DSW2#show running-config
As shown in the outputs, the DSW1′s priority is 200 and is higher than that of DSW2 so DSW1 becomes active switch for the group. Notice that the interface Gig1/0/1 on DSW1 is being tracked so when this interface goes down, HSRP automatically reduces the router’s priority by a conﬁgurable amount, in this case 5. Therefore the priority of DSW1 goes down from 200 to 195. But this value is still higher than that of DSW2 (190) so DSW1 remains the active switch for the group. To make DSW2 takes over this role, we have to configure DSW1′s decrement value with a value equal or greater than 11 so that its result is smaller than that of DSW2 (200 – 11 < 190). Therefore C is the correct answer.
During routine maintenance, G1/0/1 on DSW1 was shutdown. All other interface were up. DSW2 became the active HSRP device for Vlan101 as desired. However, after G1/0/1 on DSW1 was reactivated. DSW1 did not become the active HSRP device as desired. What need to be done to make the group for Vlan101 function properly?
Explicación: Continue to check VLAN 101 on both switches…
We learned that DSW1 doesn’t have the “standby 1 preempt” command so it can’t take over the active role again even if its priority is the highest. So we need to enable this command on VLAN 101 of DSW1.
DSW2 has not become the active device for Vlan103′s HSRP group even though all interfaces are active. As related to Vlan103′s HSRP group. What can be done to make the group function properly?
Respuesta: B o C
The reason DSW2 has not become the active switch for Vlan103 is because the priority value of DSW1 is higher than that of DSW2. In order to make DSW2 become the active switch, we need to increase DSW2′s priority (to higher than 200) or decrease DSW1′s priority (to lower than 190).
If G1/0/1 on DSW1 is shutdown, what will be the current priority value of the Vlan105′s group on DSW1?
Below is the output of VLAN 105:
If G1/0/1 on DSW1 is shutdown, its priority will decrease 55 so, its value will be 150 – 55 = 95
What is the configured priority value of the Vlan105′s group on DSW2 ?
Below is the output of VLAN 105 of DSW2:
We don’t see the priority of DSW2 so it is using the default value (100).
During routine maintenance, it became necessary to shutdown G1/0/1 on DSW1 and DSW2. All other interface were up. During this time, DSW1 became the active device for Vlan104′s HSRP group. As related to Vlan104′s HSRP group, what can be done to make the group function properly?
The question asks us how to keep the active role of DSW2. From the outputs, we learned that if both interfaces G1/0/1 of DSW1 and DSW2 are shutdown, the priority of DSW1 will be 150 – 1 = 149 and that of DSW2 will be 200 – 55 = 145 -> DSW1 will become the active switch.
The main point here is that we have to configure so in such a way that when both interfaces G1/0/1 of DSW1 and DSW2 are shutdown, the priority of DSW2 is still greater than that of DSW1. Therefore the priority value of DSW1 should be smaller than 145, or we have to configure the decrement value of DSW1 to a value greater than 6 ( 6 = 150 – 144) -> C is the correct answer.
NOTA: To keep the active role of DSW2, we can disable “preempt” on DSW1 (answer A) so that it will not take over the active role when DSW1 is downed but it also means that VLAN 104 will not have active switch -> VLAN104 will fail.