When the BGP versions supported by two BGP neighbors are inconsistent, the neighbors will negotiate to use the highest BGP version supported by both ends.

Question

Options

• ATRUE
• BFALSE

• A
  27% (7)
• B
  73% (19)

Explanation

BGP version negotiation works by negotiating down, not up - neighbors agree on the lowest version both support, not the highest. This ensures backward compatibility: if one peer only supports BGP-4 and the other supports a hypothetical newer version, they settle on BGP-4. Option A is wrong because it inverts this logic; claiming the highest shared version is used contradicts how the OPEN message exchange and version negotiation actually function in the protocol. In practice, since BGP-4 is the universal standard today, this negotiation rarely matters, but the principle remains: lowest common denominator wins.

Memory tip: Think of it like a speed limit - two cars driving together must travel at the speed of the slower one, not the faster. BGP peers sync down to the lowest shared version, keeping compatibility intact.

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