Examine the configuration shown below in a partial output of the show run command executed from Router 5.
With this configuration, which of the following is true?
A. if POS 1/0 goes down, Router 5 will become the AVG.
B. if POS 1/0 goes down, Router 5 will relinquish its role as AVG.
C. if POS 1/0 and POS 2/0 go down, Router 5 will relinquish its role as AVG.
D. if POS 1/0 and POS 2/0 go down, Router 5 will become the AVG.
Correct Answer: C
Explanation/Reference:
Answer:
If POS 1/0 and POS 2/0 go down, Router 5 will relinquish its role as active virtual gateway (AVG). The example indicates that Router 5 is configured a member of Gateway Load Balancing Protocol (GLBP) group 156 and that it is tracking the state of two of interfaces, POS 1/0 and 2/0. An initial weighting value of 120 has been assigned to the router in line 4, and upper and lower thresholds of 95 and 110 have been configured, respectively.
In lines 5 and 6, decrement values of 20 and 10 have assigned to the tracking of interface POS 1/0 and POS2/0, respectively. If either of the tracked interfaces goes down, the weight value of the router will be decreased by the amount of the decrement value. If the weight falls below the lower threshold (95), the router will relinquish its role as the AVG. If either single interface that is being tracked goes down, the weight value will not fall below the lower threshold, and the router will maintain its role of AVG. This occurs because 120 – 20 = 100, which is higher than 95 (the lowest threshold), and 120 – 10 = 110, which is also higher than 95. If both interfaces go down, the value will fall below the lower threshold (120 – 10 – 20 = 90, which is lower than 95), and the router will give up its role as the AVG.
The loss of interfaces will never cause a router to become the AVG. That can only occur if the router functioning as the current AVG in the group loses its interfaces.
The loss of either of the interfaces alone will not decrement the initial weighting value enough for it to fall below the lower threshold, and therefore will not cause the router to relinquish its role as AVG.
Objective:
Infrastructure Services Sub-Objective:
Configure and verify first-hop redundancy protocols
References:
Cisco > Home > End-of-Sale and End-of-Life Products > Cisco IOS Software Releases > 12.2T > Product Literature > White Papers > GLBP – Gateway Load Balancing Protocol Cisco > Cisco IOS IP Application Services Command Reference > threshold metric through weight (real server) > track
