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Is BP protocol next hop unique to Juniper? It is not listed as standard BGP attribute such as next hop.
Check this: https://datatracker.ietf.org/doc/html/rfc4271
For everyone so they do not need to dig into RFC:
The NEXT_HOP is a well-known mandatory attribute that defines the IP
address of the router that SHOULD be used as the next hop to the
destinations listed in the UPDATE message. The NEXT_HOP attribute is
calculated as follows:
1) When sending a message to an internal peer, if the route is not
locally originated, the BGP speaker SHOULD NOT modify the
NEXT_HOP attribute unless it has been explicitly configured to
announce its own IP address as the NEXT_HOP. When announcing a
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RFC 4271 BGP-4 January 2006
locally-originated route to an internal peer, the BGP speaker
SHOULD use the interface address of the router through which
the announced network is reachable for the speaker as the
NEXT_HOP. If the route is directly connected to the speaker,
or if the interface address of the router through which the
announced network is reachable for the speaker is the internal
peer's address, then the BGP speaker SHOULD use its own IP
address for the NEXT_HOP attribute (the address of the
interface that is used to reach the peer).
2) When sending a message to an external peer, X, and the peer is
one IP hop away from the speaker:
- If the route being announced was learned from an internal
peer or is locally originated, the BGP speaker can use an
interface address of the internal peer router (or the
internal router) through which the announced network is
reachable for the speaker for the NEXT_HOP attribute,
provided that peer X shares a common subnet with this
address. This is a form of "third party" NEXT_HOP attribute.
- Otherwise, if the route being announced was learned from an
external peer, the speaker can use an IP address of any
adjacent router (known from the received NEXT_HOP attribute)
that the speaker itself uses for local route calculation in
the NEXT_HOP attribute, provided that peer X shares a common
subnet with this address. This is a second form of "third
party" NEXT_HOP attribute.
- Otherwise, if the external peer to which the route is being
advertised shares a common subnet with one of the interfaces
of the announcing BGP speaker, the speaker MAY use the IP
address associated with such an interface in the NEXT_HOP
attribute. This is known as a "first party" NEXT_HOP
- By default (if none of the above conditions apply), the BGP
speaker SHOULD use the IP address of the interface that the
speaker uses to establish the BGP connection to peer X in the
3) When sending a message to an external peer X, and the peer is
multiple IP hops away from the speaker (aka "multihop EBGP"):
- The speaker MAY be configured to propagate the NEXT_HOP
attribute. In this case, when advertising a route that the
speaker learned from one of its peers, the NEXT_HOP attribute
of the advertised route is exactly the same as the NEXT_HOP
Rekhter, et al. Standards Track [Page 27]
RFC 4271 BGP-4 January 2006
attribute of the learned route (the speaker does not modify
the NEXT_HOP attribute).
- By default, the BGP speaker SHOULD use the IP address of the
interface that the speaker uses in the NEXT_HOP attribute to
establish the BGP connection to peer X.
Normally, the NEXT_HOP attribute is chosen such that the shortest
available path will be taken. A BGP speaker MUST be able to support
the disabling advertisement of third party NEXT_HOP attributes in
order to handle imperfectly bridged media.
A route originated by a BGP speaker SHALL NOT be advertised to a peer
using an address of that peer as NEXT_HOP. A BGP speaker SHALL NOT
install a route with itself as the next hop.
The NEXT_HOP attribute is used by the BGP speaker to determine the
actual outbound interface and immediate next-hop address that SHOULD
be used to forward transit packets to the associated destinations.
The immediate next-hop address is determined by performing a
recursive route lookup operation for the IP address in the NEXT_HOP
attribute, using the contents of the Routing Table, selecting one
entry if multiple entries of equal cost exist. The Routing Table
entry that resolves the IP address in the NEXT_HOP attribute will
always specify the outbound interface. If the entry specifies an
attached subnet, but does not specify a next-hop address, then the
address in the NEXT_HOP attribute SHOULD be used as the immediate
next-hop address. If the entry also specifies the next-hop address,
this address SHOULD be used as the immediate next-hop address for
The BGP Protocol next-hop is the well known next-hop attribute transported in BGP packets. The next-hop shown in routing tables is the resolved next-hop. This is how the router is going to reach the protocol next-hop.
All true Christophe. Let me add to that: it's not a really selection attribute, it's more a condition that must be fulfilled before the real attributes are taken into account. this describes it real nice I think Understanding BGP Path Selection | Junos OS | Juniper Networks.