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BGP Best External

BGP Best External is used in Active Standby BGP Topologies generally but not limited with that.BGP Best External feature helps BGP to converge much faster by sending external BGP prefixes which wouldn’t normally be sent if they are not overall BGP best path.

There are BGP best internal, BGP best external and BGP Overall best path.

BGP Best external in an active-standby scenarios can be used in MPLS VPN, Internet Business Customers, EBGP Peering Scenarios, Hierarchical large scale Service Provider backbone and many others.

But,How active-standby scenario connection with BGP is created ? In which situation people use active-standby instead of active-active connection ?

Let’s start with the below scenario.

bgp best external

Figure -1 BGP Active-Standby Path Selection Example

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Orhan Ergun 2 Comments

What is MP-BGP – Multiprotocol BGP

MP-BGP (Multiprotocol BGP) is an extensions to BGP protocol. Standard BGP only supports IPv4 unicast address family, whereas MP-BGP supports more than 15 different BGP address families.

RFC4760 defines the extensions for BGP protocol and states that ” in order to bring extra functionality to BGP protocol, new BGP AFI (Address Family Identifier) and BGP SAFI (Sub Address Family Identifier) is introduced”.

Multi protocol BGP supports IPv4 and IPv6 address families and their unicast and multicast variants.

MPBGP also supports Layer 2 VPN address families. EVPN (Ethernet VPN) is a mechanism which the mac addresses are exchanged between PE devices over BGP control plane. Read more