It supports a 4-byte autonomous system number: BGP on a Tier-0 Gateway supports 4-byte AS (Autonomous System) numbers, which are necessary for larger routing domains.
Can be used as an Exterior Gateway Protocol: BGP is commonly used as an Exterior Gateway Protocol to establish routing between different autonomous systems (AS).
BGP is enabled by default: On a Tier-0 Gateway, BGP is typically enabled by default, allowing administrators to configure it for external routing.