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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Checkpoint GAiA BGP Network Origination

Fri 30 January 2015

I was recently involved in a project upgrading the core firewall pair from Checkpoint R71.40 SPLAT to R77.20 GAiA. While very different, a lot of the configuration is pretty straight forward, and well documented in various articles on the Checkpoint website.

This setup runs BGP on the firewalls, to learn routes from our internal VRF's and also the WAN VRF where our MPLS …

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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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