Always Networks Blog - BGP

eBGP - ECMP in depth!

Sat 08 July 2017

My client recently did a fairly big change to the edge network in their data centre, including a migration to 4-byte AS numbers. This wasn't without it's challenges. So here is a (long) post about the challenges we faced, and some explanations of some of the more advanced features of BGP such as local-as no-prepend replace-as, and bestpath as-path multipath-relax.

Here is a very simplified …

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Non-Transitive or Transitive? - BGP Path Attributes

Sun 22 June 2014

I was reading about BGP Path Attributes and came across this table (thanks to http://netcerts.net/bgp-path-attributes-and-the-decision-process/):

--------------------------------------------------------------------- ---------------------------------------------------------- LIST OF BGP PATH ATTRIBUTES Attribute Name Category / Class ORIGIN Well-Known Mandatory AS\_PATH Well-Known Mandatory NEXT\_HOP Well-Known Mandatory LOCAL\_PREF Well-Known Discretionary ATOMIC\_AGGREGATE Well-Known Discretionary AGGREGATOR Optional Transitive COMMUNITY Optional Transitive MULTI\_EXIT\_DISC (MED) Optional Non-Transitive ORIGINATOR\_ID Optional Non-Transitive CLUSTER LIST Optional …
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