Concept Guide

Network Next Hop Metric LocPrf Weight Path
*> 7.0.0.0/29 10.114.8.33 0 0 18508 ?
*> 7.0.0.0/30 10.114.8.33 0 0 18508 ?
*> 9.2.0.0/16 10.114.8.33 10 0 18508 701 i
AS Path
The AS path is the list of all ASs that all the prexes listed in the update have passed through.
The local AS number is added by the BGP speaker when advertising to a EBGP neighbor.
NOTE: Any update that contains the AS path number 0 is valid.
The AS path is shown in the following example. The origin attribute is shown following the AS path information (shown in bold).
Example of Viewing AS Paths
DellEMC#show ip bgp paths
Total 30655 Paths
Refcount Metric Path
3 18508 701 3549 19421 i
3 18508 701 7018 14990 i
3 18508 209 4637 1221 9249 9249 i
2 18508 701 17302 i
26 18508 209 22291 i
75 18508 209 3356 2529 i
2 18508 209 1239 19265 i
1 18508 701 2914 4713 17935 i
162 18508 209 i
2 18508 701 19878 ?
31 18508 209 18756 i
2 18508 209 7018 15227 i
10 18508 209 3356 13845 i
3 18508 209 701 6347 7781 i
1 18508 701 3561 9116 21350 i
Next Hop
The next hop is the IP address used to reach the advertising router.
For EBGP neighbors, the next-hop address is the IP address of the connection between the neighbors. For IBGP, the EBGP next-hop
address is carried into the local AS. A next hop attribute is set when a BGP speaker advertises itself to another BGP speaker outside its
local AS and when advertising routes within an AS. The next hop attribute also serves as a way to direct trac to another BGP speaker,
rather than waiting for a speaker to advertise. When a next-hop BGP neighbor is unreachable, then the connection to that BGP neighbor
goes down after hold down timer expiry. The connection ap can also be obtained immediately with Fallover enabled. BGP routes that
contain the next-hop as the neighbor address are not sent to the neighbor. You can enable this feature using the neighbor sender-
side-loopdetect command.
NOTE
: For EBGP neighbors, the next-hop address corresponding to a BGP route is not resolved if the next-hop address is not
the same as the neighbor IP address.
Multiprotocol BGP
MBGP is an extensison of BGP to carry routing information for multiple network-layer protocols such as IPv4 unicast and multicast, and
IPv6 unicast. MBGP provides support for multiple network layer protocol address families that allows to dene independent policy and
peering congurations. MBGP carries dierent set of routes depending on the protocol. It carries routing information for IPv4 multicast and
IPv6 unicast routes. Multiprotocol extensions for BGP (MBGP) is dened in IETF RFC 2858. MBGP allows dierent types of address
families to be distributed in parallel.
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Border Gateway Protocol (BGP)