BGP which OSI layer?

sydneysundar

All,

I am attempting CISSP questions from SH .. BGP is marked as a routing protocol in network.. while BGP (border gateway protocol) is at application layer by many other sources(coutesy google)..

as gateway are operating at Application layer, this is confusing..

please explain.

regards
sundar

warriorfan808

I'll take a shot at it. BGP is treated a little different because it runs on TCP port 179, which is an application port. Just like other applications, it's defined in the Application layer. I know it's a bit odd because it's a routing protocol and when people think routing, they think the Network Layer.

TheFORCE

sydneysundar wrote: »

All,

I am attempting CISSP questions from SH .. BGP is marked as a routing protocol in network.. while BGP (border gateway protocol) is at application layer by many other sources(coutesy google)..

as gateway are operating at Application layer, this is confusing..

please explain.

regards
sundar

You are getting confused by the word "network" BGP is used to exchange routing information between AS's, the book doesnt say that BGP is operating at the network layer rather it helps route information between networks.

sydneysundar

Many thanks..

this came in the practise questions that came along in the CD-ROM.

Hunter85

well google says it works in network layer

ScottFiesta

Here's a great reference chart in PDF that shows all the protocols mapped to the OSI model plus full acronym lists and other helpful info (PRINT AND LAMINATE FOR REFERENCE). I've read both RFCs (090400 & 1771) and neither are very helpful in clarifying things. Wikipedia lists BGP as Layer 7 but EGP, OSPF, EIGRP etc as Layer 3.

I don't understand how EGP can be in Layer 3 but BGP can be in 7. I would, however, hazard a guess that my delving too much deeper into this wouldn't be a prudent expenditure of my study time.

ScottFiesta

ScottFiesta wrote: »

Here's a great reference chart in PDF that shows all the protocols mapped to the OSI model plus full acronym lists and other helpful info (PRINT AND LAMINATE FOR REFERENCE). I've read both RFCs (090400 & 1771) and neither are very helpful in clarifying things. Wikipedia lists BGP as Layer 7 but EGP, OSPF, EIGRP etc as Layer 3.

I don't understand how EGP can be in Layer 3 but BGP can be in 7. I would, however, hazard a guess that my delving too much deeper into this wouldn't be a prudent expenditure of my study time.

https://web.archive.org/web/20120529200700/http://www.wildpackets.com/elements/misc/WP_encapsulation_chart.pdf
and there is the link to the chart

Gess

I made my own OSI Model matrix and had BGP at Layer 3 (Networking) with the routing protocols.