Decrease Network Convergence Time with Integrated IS-IS Configuration
Question
A network engineer wants to decrease the convergence time of a network that is running integrated IS-IS as an IGP, at the expense of bandwidth and CPU usage.
Which two configuration tasks achieve this goal? (Choose two.)
Answers
Explanations
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A. B. C. D. E.BD.
https://books.google.co.in/books?id=u_XOQy4cBkgC&pg=PA184&lpg=PA184&dq=what+is+hello+multiplier+minimal+time+in+integrated+is-Integrated IS-IS is an Interior Gateway Protocol (IGP) that is commonly used in Service Provider networks. Its convergence time is critical for providing fast and reliable network services. The convergence time is the duration it takes for the network to restore full connectivity after a topology change. The faster the convergence time, the better the network performance.
To decrease the convergence time of a network that is running integrated IS-IS as an IGP, at the expense of bandwidth and CPU usage, the following two configuration tasks should be performed:
B. Configure the hello interval to be minimal. E. Configure the hello multiplier to be 3.
Explanation:
Hello interval: Integrated IS-IS uses Hello messages to establish and maintain neighbor relationships between routers. The Hello interval determines how often Hello messages are sent. By default, the Hello interval is 10 seconds. Configuring the Hello interval to be minimal, which is 1 second, allows the routers to detect link failures and other topology changes more quickly. This results in faster convergence times. However, it increases the amount of Hello traffic on the network, which consumes more bandwidth and CPU resources.
Hello multiplier: The Hello multiplier determines the number of Hello messages that can be missed before a neighbor is considered down. By default, the Hello multiplier is 3. Configuring the Hello multiplier to be 3 again makes the network converge faster, as it takes fewer missed Hello messages to trigger a neighbor down event. However, it also increases the amount of Hello traffic on the network, which consumes more bandwidth and CPU resources.
Options A and D are incorrect because they only modify the timers that determine how long a router waits for a response from a neighbor. This does not affect the frequency of Hello messages or the number of missed Hellos that trigger a neighbor down event. Option C is incorrect because disabling Hello-padding does not affect the Hello interval or the Hello multiplier. It only reduces the size of Hello messages, which may save some bandwidth, but it does not significantly affect the convergence time.
