I checked the encoding of the attribute, the errata looks correct to me
also.
Thanks,
Colin
On 13/07/2021 15:22, Warren Kumari wrote:
[ - RFC Editor (for clutter) ]
Dear GROW,
AFAICT, this errata is correct, and should be Verified, but I'd like
some confirmation / double-checkin'.
Note that there is already a somewhat related errata:
https://www.rfc-editor.org/errata_search.php?rfc=6396&rec_status=0
Please let me know by Friday (July 16th) if you disagree with the Errata.
W
On Tue, Jul 13, 2021 at 9:01 AM RFC Errata System
<[email protected]> wrote:
The following errata report has been submitted for RFC6396,
"Multi-Threaded Routing Toolkit (MRT) Routing Information Export Format".
--------------------------------------
You may review the report below and at:
https://www.rfc-editor.org/errata/eid6640
--------------------------------------
Type: Technical
Reported by: Claudio Jeker <[email protected]>
Section: Appendix A
Original Text
-------------
| BGP Path Attributes =
40 01 01 00 50 02 00 0e 02 03 00 00 fb f0 00 00
fb ff 00 00 fb f6 80 0e 2b 00 02 01 20 20 01 0d
b8 00 0d 00 ff 00 00 00 00 00 00 01 87 fe 80 00
00 00 00 00 00 02 12 f2 ff fe 9f 1b 00 00 00 20
20 01 0d b8
Figure 19: MRT RIB_IPV6_UNICAST Example
The contents of the BGP Path Attribute field above are as follows:
ORIGIN: IGP
ASPATH: 64496 64511 64502
MP_REACH_NLRI(IPv6 Unicast)
NEXT_HOP: 2001:db8:d:ff::187
NEXT_HOP: fe80::212:f2ff:fe9f:1b00
NLRI: 2001:0DB8::/32
Figure 20: BGP Path Attribute Contents
Corrected Text
--------------
| BGP Path Attributes =
40 01 01 00 50 02 00 0e 02 03 00 00 fb f0 00 00
fb ff 00 00 fb f6 80 0e 21 20 20 01 0d b8 00 0d
00 ff 00 00 00 00 00 00 01 87 fe 80 00 00 00 00
00 00 02 12 f2 ff fe 9f 1b 00
Figure 19: MRT RIB_IPV6_UNICAST Example
The contents of the BGP Path Attribute field above are as follows:
ORIGIN: IGP
ASPATH: 64496 64511 64502
MP_REACH_NLRI(IPv6 Unicast)
NEXT_HOP: 2001:db8:d:ff::187
NEXT_HOP: fe80::212:f2ff:fe9f:1b00
Figure 20: BGP Path Attribute Contents
Notes
-----
The encoding of the MP_REACH_NLRI attribute is not in the form according to
Section 4.3.4. RIB Entries:
There is one exception to the encoding of BGP attributes for the BGP
MP_REACH_NLRI attribute (BGP Type Code 14) [RFC4760]. Since the AFI,
SAFI, and NLRI information is already encoded in the RIB Entry Header
or RIB_GENERIC Entry Header, only the Next Hop Address Length and
Next Hop Address fields are included. The Reserved field is omitted.
The attribute length is also adjusted to reflect only the length of
the Next Hop Address Length and Next Hop Address fields.
The example includes a full MP_REACH_NLRI attribute. This is a common issue
with TABLE_DUMP_V2 and parsers need to implement a workaround to support the
broken form.
One way of solving this is to compare the attribute length of MP_REACH_NLRI
with the first byte of the attribute.
If the value of the first byte is equal to the attribute lenght - 1 then it is
the RFC encoding else assume that a full MP_REACH_NLRI attribute was dumped in
which case the parser needs to skip the first 3 bytes to get to the nexthop.
Instructions:
-------------
This erratum is currently posted as "Reported". If necessary, please
use "Reply All" to discuss whether it should be verified or
rejected. When a decision is reached, the verifying party
can log in to change the status and edit the report, if necessary.
--------------------------------------
RFC6396 (draft-ietf-grow-mrt-17)
--------------------------------------
Title : Multi-Threaded Routing Toolkit (MRT) Routing Information
Export Format
Publication Date : October 2011
Author(s) : L. Blunk, M. Karir, C. Labovitz
Category : PROPOSED STANDARD
Source : Global Routing Operations
Area : Operations and Management
Stream : IETF
Verifying Party : IESG
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