[BGPCEP-454] Make Next-Hop mandatory BGP path attribute Created: 25/Apr/16  Updated: 03/Mar/19  Resolved: 03/Jun/16

Status: Resolved
Project: bgpcep
Component/s: BGP
Affects Version/s: Bugzilla Migration
Fix Version/s: Bugzilla Migration

Type: Bug
Reporter: Milos Fabian Assignee: Ajay L
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

Operating System: All
Platform: All

External issue ID: 5791

 Description   

https://tools.ietf.org/html/rfc4271#section-5.1.3 defines NEXT_HOP as a mandatory BGP Path attribute, however might have a zero length (i.e. Flowspec).

 Comments   
Comment by Ajay L [ 03/May/16 ]

Approach used for the fix
--------------------------

From RFC 4271, ORIGIN, AS_PATH and NEXT_HOP are mandatory attributes. The rules to decide when the mandatory attributes should be present are specified in this RFC and in RFC 4760:

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.

An UPDATE message that carries no NLRI, other than the one encoded in
the MP_REACH_NLRI attribute, SHOULD NOT carry the NEXT_HOP attribute.
If such a message contains the NEXT_HOP attribute, the BGP speaker
that receives the message SHOULD ignore this attribute.

An UPDATE message that carries the MP_REACH_NLRI MUST also carry the
ORIGIN and the AS_PATH attributes (both in EBGP and in IBGP
exchanges). Moreover, in IBGP exchanges such a message MUST also
carry the LOCAL_PREF attribute.

If any of the mandatory attribute is found missing, appropriate notification message is sent as per format defined in RFC 4271. Also as per the spec, BGP connection is closed immediately after it is sent.

Comment by Ajay L [ 03/May/16 ]

https://git.opendaylight.org/gerrit/#/c/38296/

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