Cisco
300-415 · Question #296
300-415 Question #296: Real Exam Question with Answer & Explanation
The correct answer is B: same BGP AS between all CE and PE routers. To avoid BGP routing loops for routes advertised between data center sites in an SD-WAN fabric, configuring all relevant BGP routers with the same BGP Autonomous System (AS) leverages internal BGP loop prevention mechanisms.
WAN Edge Router Deployment
Question
An engineer must avoid routing loops on the SD-WAN fabric for routes advertised between data center sites. Which BGP loop prevention attribute must be configured on the routers to meet this requirement?
Options
- Astatic routing on all WAN Edge routers instead of BGP
- Bsame BGP AS between all CE and PE routers
- Csame OMP overlay-as on WAN Edge routers of all data centers
- Dsame BGP AS between all WAN Edge routers and CE routers
Explanation
To avoid BGP routing loops for routes advertised between data center sites in an SD-WAN fabric, configuring all relevant BGP routers with the same BGP Autonomous System (AS) leverages internal BGP loop prevention mechanisms.
Common mistakes.
- A. Static routing avoids BGP loops but does not address BGP-specific loop prevention attributes, which is what the question asks for.
- C. OMP overlay-as is a loop prevention attribute for the Overlay Management Protocol (OMP), not specifically for BGP routing loops as requested in the question.
- D. The configuration of the same BGP AS between WAN Edge routers and their directly connected CE routers describes local peering, but doesn't inherently prevent routing loops for routes advertised between data center sites without further context or architectural assumptions.
Concept tested. BGP loop prevention, iBGP split-horizon
Topics
#BGP#Loop Prevention#AS-Path#SD-WAN Routing
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