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BGP Path Attributes – Origin

The Origin attribute informs the Autonomous Systems (AS) about the originator of that route. It is a Well-Known Mandatory BGP Path attribute. It is supported in all BGP implementations and in all update packets it must exist.

There are three different Origin type. These are :

• i (IGP)
• e (EGP)
• ? (Incomplete)

i (IGP) routes are the routes which are originated from a routing protocol, like RIP, OSPF, EIGRP etc. Generally this is done via network command under the BGP process.

e (EGP) routers are the routes which are originated from External Gateway Protocol (EGP). Now the only EGP is BGP, so this is the routes originatd from BGP.

? (Incomplete) routes are the routes which are Redistributed from static, IGP etc. into the BGP.

You can see any BGP route’s origin with “show ip bgp” command. At the end of the output table, the origin code ( i, e or ?) is shown.

Let’s check the bgp routes of the below topology.

bgp path attribute, origin

BGP Path Attribute, Origin

In the output of “show ip bgp” command, you can see the origin code values of the routes. As you can see, in the bgp route table above, there are two routes and two of these routes are i (IGP) routes.

You can find other BGP Path Attribute Articles below:

BGP Path Attributes – Weight
BGP Path Attributes – Local Preference
BGP Path Attributes – AS Path
BGP Path Attributes – Origin
BGP Path Attributes – MED

Main BGP Article Series :

BGP – Part 1
BGP – Part 2 (BGP Peers, BGP Sessions, BGP Messages)
BGP – Part 3 (IBGP, IBGP Topologies and EBGP)
BGP – Part 4 (BGP Administrative Distance and BGP Path Attributes)
BGP – Part 5 (Packet Tracer BGP Configuration Example)

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About the Author
Gokhan Kosem is a telecommunation and network engineer. His ambition to IP networks and end-to-end system installation made him to prepare this web-site. By sharing his experiences about various networking protocols beside different system installation experiences and Cisco, Juniper, Alcatel-Lucent devices configurations, he is aimed to be helpful for his collegues in all over the world. He is currently lives in Istanbul, Turkey.

One comment for “BGP Path Attributes – Origin”

1
Farrukh

Thanks for this help. Really appreciated.

August 31st, 2016 at 09:34

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