A NOTIFICATION message is sent when an error condition is detected. The BGP connection is closed immediately after it is sent. In addition to the fixed-size BGP header, the NOTIFICATION message contains the following fields:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error code | Error subcode | Data (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Error Code:
This 1-octet unsigned integer indicates the type of
NOTIFICATION. The following Error Codes have been defined:
Error Code Symbolic Name Reference
1 Message Header Error Section 6.1
2 OPEN Message Error Section 6.2
3 UPDATE Message Error Section 6.3
4 Hold Timer Expired Section 6.5
5 Finite State Machine Error Section 6.6
6 Cease Section 6.7
Error subcode:
This 1-octet unsigned integer provides more specific
information about the nature of the reported error. Each Error
Code may have one or more Error Subcodes associated with it.
If no appropriate Error Subcode is defined, then a zero
(Unspecific) value is used for the Error Subcode field.
Message Header Error subcodes:
1 - Connection Not Synchronized.
2 - Bad Message Length.
3 - Bad Message Type.
OPEN Message Error subcodes:
1 - Unsupported Version Number.
2 - Bad Peer AS.
3 - Bad BGP Identifier.
4 - Unsupported Optional Parameter.
5 - \[Deprecated - see Appendix A\].
6 - Unacceptable Hold Time.
UPDATE Message Error subcodes:
1 - Malformed Attribute List.
2 - Unrecognized Well-known Attribute.
3 - Missing Well-known Attribute.
4 - Attribute Flags Error.
5 - Attribute Length Error.
6 - Invalid ORIGIN Attribute.
7 - \[Deprecated - see Appendix A\].
8 - Invalid NEXT_HOP Attribute.
9 - Optional Attribute Error.
10 - Invalid Network Field.
11 - Malformed AS_PATH.
Data:
This variable-length field is used to diagnose the reason for
the NOTIFICATION. The contents of the Data field depend upon
the Error Code and Error Subcode. See Section 6 for more
details.
Note that the length of the Data field can be determined from
the message Length field by the formula:
Message Length = 21 + Data Length
The minimum length of the NOTIFICATION message is 21 octets (including message header).
object bgp_notification_message = {
type this = struct {
error_code: bgp_error_code,
error_subcode: bgp_error_subcode,
data: stream_data # TODO for now we cannot knwo the size of the message, use envvar ?
}
}
action bgp_notification_message_event(src:bgp_id,dst:bgp_id,bgp_message:bgp_notification_message) = {}
relation is_errored(C:bgp_id)
around bgp_notification_message_event(src:bgp_id,dst:bgp_id,bgp_message:bgp_notification_message) {
require isup(bgpid_to_endpoint(src));
require open_message_recv(src) & open_message_recv(dst);
require is_errored(src);
require bgp_message.error_code = bgp_error_code.header_mess_error |
bgp_message.error_code = bgp_error_code.open_mess_error |
bgp_message.error_code = bgp_error_code.update_mess_error |
bgp_message.error_code = bgp_error_code.hold_timer_expire |
bgp_message.error_code = bgp_error_code.fsm_error |
bgp_message.error_code = bgp_error_code.cease_error;
require bgp_message.error_code = bgp_error_code.open_mess_error -> (bgp_message.error_subcode = bgp_open_error_subcode.unsupported_version_number | bgp_message.error_subcode = bgp_open_error_subcode.bad_peer_as | bgp_message.error_subcode = bgp_open_error_subcode.bad_bgp_identifier | bgp_message.error_subcode = bgp_open_error_subcode.unsupported_optional_parameter | bgp_message.error_subcode = bgp_open_error_subcode.unacceptable_hold_time | bgp_message.error_subcode = bgp_open_error_subcode.unsupported_capability);
require bgp_message.error_code = 3 -> (bgp_message.error_subcode >= 1 & bgp_message.error_subcode <= 11);ยค
...
require isup(bgpid_to_endpoint(src));
}