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Fortinet NSE 7 – SD-WAN 7.0: Speed up routing convergence in BGP?

By: Author Alex Lim

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Categories Exam

Question

Which two settings can you configure to speed up routing convergence in BGP? (Choose two.)

A. update-source
B. set-route-tag
C. holdtime-timer
D. link-down-failover

Answer

C. holdtime-timer
D. link-down-failover

Explanation

BGP (Border Gateway Protocol) is a routing protocol that exchanges routing information between autonomous systems (AS) on the internet or within a network. BGP can be used to implement SD-WAN by dynamically selecting the best path for traffic based on various criteria such as latency, bandwidth, cost, or policy. However, BGP can also have slow convergence time, which means the time it takes for all routers to agree on the network topology after a change occurs. Slow convergence can cause packet loss, increased latency, and reduced performance. There are several settings that can be configured to speed up routing convergence in BGP, such as:

C. holdtime-timer: This setting determines how long a router waits before declaring a neighbor unreachable after not receiving any keepalive messages from it. A lower holdtime-timer can help detect link failures faster and trigger route updates sooner.

D. link-down-failover: This setting enables a router to immediately remove any routes learned from a neighbor when the link to that neighbor goes down, instead of waiting for the holdtime-timer to expire. This can help reduce convergence time and avoid routing loops.

The other statements are false because:

A. update-source: This setting specifies the source IP address that a router uses to establish BGP sessions with its neighbors. It does not affect routing convergence time.

B. set-route-tag: This setting assigns a numerical value to a route that can be used for filtering or policy-based routing purposes. It does not affect routing convergence time.

Reference

Fortinet NSE 7 – SD-WAN 7.0 (NSE7_SDW-7.0) certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the Fortinet NSE 7 – SD-WAN 7.0 (NSE7_SDW-7.0) exam and earn Fortinet NSE 7 – SD-WAN 7.0 (NSE7_SDW-7.0) certification.