Huawei Quidway S6500 Series Operation Manual page 228

Operation Manual - Routing Protocol
Quidway S6500 Series Ethernet Switches
Chapter 6 BGP Configuration
6.1 Brief Introduction to BGP
6.1.1 BGP Overview
Border gateway protocol (BGP) is an inter-autonomous system (inter-AS) dynamic
route discovery protocol. Three early versions of BGP are BGP-1 (RFC1105), BGP-2
(RFC1163) and BGP-3 (RFC1267). The current version is BGP-4 (RFC1771) that is
applied to distributed structures and supports classless inter-domain routing (CIDR).
Actually, BGP-4 is becoming the external routing protocol standard of the Internet,
which is frequently used between ISPs.
The characteristics of BGP are as follows:
BGP is an external gateway protocol (EGP). Different from such internal routing
protocols as OSPF and RIP, it focuses on route propagation control and selection
of best routes other than discovery and calculation of routes.
It eliminates routing loop by adding AS path information to BGP routes.
It enhances its own reliability by using TCP as the transport layer protocol.
When routes are updated, BGP only transmits updated routes, which greatly
reduces bandwidth occupation by route propagation and can be applied to
propagation of a great amount of routing information on the Internet.
BGP-4 supports CIDR, which is an important improvement to BGP-3.
In consideration of management and security, users desire to perform control over
outgoing and incoming routing information of each AS. BGP-4 provides abundant
route policies to implement flexible filtering and selecting of routes.
BGP-4 can be extended easily to support new developments of the network.
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Chapter 6 BGP Configuration