BGP: Difference between revisions
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= iBGP vs eBGP = |
= iBGP vs eBGP = |
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5. Next hop remains unchanged when route is advertised to IBGP peer; however, it is changed when it is advertised to EBGP peer by default. |
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For IBGP peers dont need to be directly connected. |
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Next-hop IP will not be changed when adv prefixes to another IBGP. |
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Also, if you check the way BGP choose the best route to put in the routing table you'll see that EBGP is preferred. |
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And BGP can run in two modes that each has a very different behavior when advertising routing information. |
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EBGP: external BGP runs between routers in different ASs. |
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IBGP: internal BGP runs between routers in the same AS. |
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! eBGP !! iBGP |
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⚫ | | By default, EBGP peers are set with TTL = 1, which means neighbors are assumed to be directly connected.<br />We can change this behavior for EBGP by using command “neighbor x.x.x.x ebgp-multihop <TTL>”. <br />Multihop is the term used in EBGP only.|| For IBGP peers dont need to be directly connected. |
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⚫ | | Next hop remains unchanged when route is advertised to IBGP peer.<br />It is changed when it is advertised to EBGP peer by default.<br />This default behavior of IBGP can be changed by the command “neighbor x.x.x.x next-hop-self”;<br /> this changes the next hop, while advertising, as a local route. || Next-hop IP will not be changed when adv prefixes to another IBGP. |
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EBGP: routes received from an EBGP peer can be advertised to EBGP and IBGP peers. |
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IBGP: routes received from an IBGP peer cannot be advertised to another IBGP peer but can be advertised to an EBGP peer. |
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