Editing Border Gateway Protocol (section)

=== Notification ===

If there is an error it is because one of the fields in the OPEN or UPDATE message does not match between the peers, e.g., BGP version mismatch, the peering router expects a different My AS, etc. The router then sends a Notification message to the peer indicating why the error occurred.

{| class="wikitable  mw-collapsible mw-collapsed" style="margin: 0 auto; text-align:center"
|+ Error Codes
! rowspan="2" |Error Code !! rowspan="2" |Name !! colspan="2" |subcodes
|-
|Code || Name
|-
|rowspan="3" | 1 || rowspan="3" |Message Header Error || 1 || style="text-align:left"| Connection Not Synchronized
|-
| 2 || style="text-align:left"| Bad Message Length
|-
| 3 || style="text-align:left"| Bad Message Type
|-
|rowspan="6" | 2 || rowspan="6" |OPEN Message Error || 1 || style="text-align:left"| Unsupported Version Number.
|-
|2 || style="text-align:left"| Bad Peer AS.
|-
| 3 || style="text-align:left"| Bad BGP Identifier.
|-
| 4 || style="text-align:left"|Unsupported Authentication Code.
|-
| 5 || style="text-align:left"|Authentication Failure.
|-
| 6 || style="text-align:left"|Unacceptable Hold Time.
|-
| rowspan="11" |3 || rowspan="11"; style="text-align:left"|UPDATE Message Error || 1 || style="text-align:left"|Malformed Attribute List.
|-
| 2 || style="text-align:left"|Unrecognized Well-known Attribute.
|-
| 3 || style="text-align:left"|Missing Well-known Attribute.
|-
| 4 || style="text-align:left"|Attribute Flags Error.
|-
| 5 || style="text-align:left"|Attribute Length Error.
|-
| 6 || style="text-align:left"|Invalid ORIGIN Attribute
|-
| 7 || style="text-align:left"|AS Routing Loop.
|-
| 8 || style="text-align:left"|Invalid NEXT_HOP Attribute.
|-
| 9 || style="text-align:left"|Optional Attribute Error.
|-
| 10 || style="text-align:left"|Invalid Network Field.
|-
| 11 || style="text-align:left"|Malformed AS_PATH.
|-
| 4 || colspan="3" |Hold Timer Expired
|-
| 5 || colspan="3" |Finite State Machine Error
|-
| 6 || colspan="3" |Cease
|}

'''Example of NOTIFICATION Message'''
 Type: NOTIFICATION Message (3)
 Major error Code: OPEN Message Error (2)
 Minor error Code (Open Message): Bad Peer AS (2)
 Bad Peer AS: 65200