Cisco
352-001 · Question #244
352-001 Question #244: Real Exam Question with Answer & Explanation
The correct answer is B: configure EBGP fast external fallover. EBGP fast external fallover detects a directly connected link failure instantly via interface state and immediately resets the EBGP session, making it the fastest convergence mechanism for point-to-point link failures.
Question
What is the most effective way to improve BGP convergence in the event that a point-to-point link, over which an EBGP session is running, fails?
Options
- Areduce the keepalive timer to the minimum value allowed
- Bconfigure EBGP fast external fallover
- Cuse BGP multihop
- Denable BGP graceful restart
Explanation
EBGP fast external fallover detects a directly connected link failure instantly via interface state and immediately resets the EBGP session, making it the fastest convergence mechanism for point-to-point link failures.
Common mistakes.
- A. Lowering the keepalive timer reduces the hold timer expiry window but still requires waiting through multiple missed keepalive intervals before the session is declared down, making it slower than an interface-state-driven mechanism.
- C. BGP multihop (ebgp-multihop) allows EBGP peering across non-directly connected routers and is unrelated to improving convergence speed when a direct point-to-point link fails.
- D. BGP graceful restart is designed to preserve forwarding state and delay route withdrawal during a BGP speaker reload, which intentionally slows convergence to maintain traffic flow - the opposite of what is needed here.
Concept tested. EBGP fast external fallover for link failure convergence
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