Re: [bess] Encoding a 20 bit label in a 24 bit field.

[John E Drake <[e-mail]>]

I don't think that's a good idea because depending upon their position in the stack, these labels may not be at the bottom of the stack.

Yours Irrespectively,

John

> -----Original Message-----
> From: BESS <[e-mail]> On Behalf Of Zhuangshunwan
> Sent: Monday, October 15, 2018 9:02 PM
> To: Jakob Heitz (jheitz) <[e-mail]>; BESS <[e-mail]>
> Subject: Re: [bess] Encoding a 20 bit label in a 24 bit field.
> 
> It is good to make this explicit. This ambiguity has led to some unnecessary
> interworking problems.
> 
> Should we also need to explicitly define the "bottom of stack" bit in the low-
> order bit of the 3-octet label field?
> 
> Thanks,
> Shunwan
> 
> -----Original Message-----
> From: BESS [mailto:[e-mail]] On Behalf Of Jakob Heitz (jheitz)
> Sent: Tuesday, October 16, 2018 4:21 AM
> To: BESS <[e-mail]>
> Subject: [bess] Encoding a 20 bit label in a 24 bit field.
> 
> We have proposed the following erratum for RFC 7432.
> 
> Opinions?
> 
> Regards,
> Jakob.
> 
> 
> -----Original Message-----
> From: RFC Errata System <[e-mail]>
> Sent: Friday, October 12, 2018 12:37 PM
> To: Ali Sajassi (sajassi) <[e-mail]>; [e-mail];
> [e-mail]; [e-mail]; [e-mail];
> [e-mail]; [e-mail]; [e-mail];
> [e-mail]; [e-mail]; Giles Heron
> (giheron) <[e-mail]>; [e-mail]
> Cc: Krishnamoorthy Arumugham (karumugh) <[e-mail]>;
> [e-mail]; [e-mail]
> Subject: [Technical Errata Reported] RFC7432 (5523)
> 
> The following errata report has been submitted for RFC7432, "BGP MPLS-
> Based Ethernet VPN".
> 
> --------------------------------------
> You may review the report below and at:
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.rfc-
> 2Deditor.org_errata_eid5523&d=DwICAg&c=HAkYuh63rsuhr6Scbfh0UjBXeM
> K-ndb3voDTXcWzoCI&r=CRB2tJiQePk0cT-h5LGhEWH-
> s_xXXup3HzvBSMRj5VE&m=IvOdDW_zoH5heXCCcs7ke0vmlQ0Hm1yCi17llZn
> BdsY&s=n_iX5KAK2InG-bgMnZHO3o4PH9UZmYKVtes9H7-vA1E&e=
> 
> --------------------------------------
> Type: Technical
> Reported by: Krishnamoorthy Arumugham <[e-mail]>
> 
> Section: 7
> 
> Original Text
> -------------
> Clarifications to following sub-sections:
> Section 7.1
> Section 7.2
> Section 7.5
> 
> 
> Corrected Text
> --------------
> Section 7.1:
> Add below text to the section 7.1 regarding the encoding of MPLS label:
> 
> "The value of the 20-bit MPLS label is encoded in the high-order 20 bits of the
> 3 bytes MPLS Label field."
> 
> Section 7.2:
> Add below text to the section 7.2 regarding the encoding of both the MPLS
> label fields:
> 
> "The value of the 20-bit MPLS label is encoded in the high-order 20 bits of the
> 3 bytes MPLS Label field for both MPLS Label1 and MPLS Label2."
> 
> Section 7.5:
> Add below text to the section 7.5 regarding the encoding of ESI Label fields:
> 
> "The value of the 20-bit MPLS label is encoded in the high-order 20 bits of the
> ESI Label field."
> 
> 
> Notes
> -----
> MPLS label is a 20-bit value and is stored in a 3 bytes field in a packet. The 20-
> bit MPLS label value is generally stored in higher order 20 bits of the 3 byte
> label field. The exact encoding to be followed for storing MPLS label values
> are not explicitly mentioned in the RFC 7432 under section 7.1, 7.2 and 7.5
> for different types of EVPN routes. This lead to ambiguity in different
> implementations. Hence a clarification is required.
> 
> 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.
> 
> --------------------------------------
> RFC7432 (draft-ietf-l2vpn-evpn-11)
> --------------------------------------
> Title               : BGP MPLS-Based Ethernet VPN
> Publication Date    : February 2015
> Author(s)           : A. Sajassi, Ed., R. Aggarwal, N. Bitar, A. Isaac, J. Uttaro, J.
> Drake, W. Henderickx
> Category            : PROPOSED STANDARD
> Source              : Layer 2 Virtual Private Networks
> Area                : Routing
> Stream              : IETF
> Verifying Party     : IESG
> 
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