What is the purpose of a BGP confederation?

Question

Options

• AIt limits the number of routes a device receives from its peers, which reduces CPU load.
• BIt improves service by increasing the number of simultaneous iBGP peering sessions.
• CIt redirects traffic away from route reflectors, which reduces their operating load.
• DIt reduces the number of iBGP peers and increases stability.

• A
  7% (1)
• B
  7% (1)
• D
  87% (13)

Explanation

A BGP confederation is a scalability technique used within a single Autonomous System (AS) to reduce the complexity of iBGP full-mesh peering requirements. By default, all iBGP routers in an AS must maintain a full mesh of peering sessions, which scales as O(n²) - impractical for large networks. A confederation divides the AS into multiple sub-ASes (confederation member ASes). Routers within each sub-AS maintain a full iBGP mesh only among themselves, and sub-ASes peer with each other using eBGP-like sessions (but treated internally as iBGP). This dramatically reduces the total number of required iBGP sessions, which lowers CPU and memory overhead and increases overall network stability. Option A describes route filtering (not confederation). Option B is incorrect - confederations reduce, not increase, simultaneous sessions. Option C describes route reflector offloading, which is a different iBGP scaling mechanism.

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