BGP Local Preference
BGP Local Preference is a BGP attribute that is used for Outbound path manipulation in today’s Computer Networks. Path manipulation is known as BGP Traffic Engineering as well and the Local Preference attribute is the most common technique for it in real networks. In this blog post I will be explaining the use case, comparison with other outbound path manipulation techniques, and how the BGP Local Preference attribute works we will understand.
First of all, we should know that it is not a Cisco specific attribute, it is a standard attribute, which is used in other vendor equipment as well. Vendor interoperability works without issue.
Because a picture is worth a thousand words, let’s have a look at the below topology to understand how it works.

In the above topology, AS65000 has two paths to AS1.
Prefixes from AS1 are learned via two paths but AS65000 wants to use the left path as a Primary Path and the right path as a backup path.
The reason in real-life people wants to use their links as primary and backup this way is usually a cost. One of the links might be expensive and another can be cheaper, and they may want Continue reading





