In our earlier blogs, we’ve mentioned BGP native reference attribute, on this article, we are going to focus on the BGP originate attribute.
What’s BGP Origin Attribute?
The aim of the origin attribute in BGP is to maintain monitor of the supply of a prefix. This attribute can have one among three values: IGP, EGP, or Incomplete.
- i (IGP) – Originated from an inside gateway protocol (resembling EIGRP,RIP and many others).This means the route was injected into BGP by way of the community command beneath the BGP course of.
- e (EGP) – Originated from an exterior gateway protocol.
- ? (incomplete) – Unknown origin. This normally signifies the route was redistributed into BGP (from both related, static, or IGP routes). An origin code of “?” is the least most well-liked.
- From amongst the above 3 origin codes, “i”is essentially the most most well-liked whereas “?” is the least most well-liked.
Associated- iBGP vs eBGP
Situation Instance
Beneath is the situation the place 3 Routers R1, R2 and R3 are related in serial. With every in numerous Autonomous system no i.e. 1, 2 and three respectively.
Within the BGP routing desk of R2 , the BGP origin code is listed on the finish of every line within the desk –
The “i” on the finish of the primary routing entry signifies the 1.1.1.0/24 community was originated by way of an IGP, by way of the BGP community command. The three.3.3.0/24 community was redistributed into BGP in AS 3, because it reveals “?” on the finish of that routing entry.
What’s the significance of BGP Origin Attribute?
Origin Attribute is the essential issue when BGP is using algorithm to find out one of the best path to a vacation spot community. This attribute is vital in resolving conflicts between numerous various paths out there within the community. This attribute comes beneath necessary attribute therefore receives important consideration in our updates.
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