Learn how to reduce Direct Connect failover time from minutes to seconds by configuring Bidirectional Forwarding Detection on the AWS VPC interfaces for the fastest path failure detection.
Table of Contents
Question
A company has critical VPC workloads that connect to an on-premises data center through two redundant active-passive AWS Direct Connect connections. However, a recent outage on one Direct Connect connection revealed that it takes more than a minute for traffic to fail over to the secondary Direct Connect connection. The company wants to reduce the failover time from minutes to seconds.
Which solution will provide the LARGEST reduction in the BGP failover time?
A. Reduce the BGP hold-down timer that is configured on the BGP sessions on the Direct Connect connection VIFs.
B. Configure an Amazon CloudWatch alarm for the Direct Connect connection state to invoke an AWS Lambda function to fail over the traffic.
C. Configure Bidirectional Forwarding Detection (BFD) on the Direct Connect connections on the AWS side.
D. Configure Bidirectional Forwarding Detection (BFD) on the Direct Connect connections on the on-premises router.
Answer
C. Configure Bidirectional Forwarding Detection (BFD) on the Direct Connect connections on the AWS side.
Explanation
BFD allows rapid detection and response to failures in the data path between two networking devices. When configured on AWS Direct Connect VIFs, it allows almost immediate failover between active-passive connections in the event of a failure.
While reducing the BGP hold timer (A) helps, it still relies on the normal BGP convergence process which takes longer than BFD.
Configuring BFD on the on-premises router (D) still relies on BGP convergence between the router and AWS edge.
A Lambda function triggered by a CloudWatch alarm (B) adds latency compared to the near-instantaneous failover of BFD.
Only configuring BFD on the AWS Direct Connect VIFs (C) leverages its sub-second detection and failover capabilities to provide the largest reduction in failover time down to just a few seconds maximum.
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