All,
All exchanged arguments are valid.
I think a protocol draft describes protocol issues, values, TLV, etc. and not
network element mechanisms. The challenge now would be to cover notes
pointing out how to code pre version and RFC version - that was agreed last
meeting.
But what's missing in that game is a short description that both peers (BRAS
& AN) need to identify which SW version to choose based on sub version value.
A mechnism in detail for detection and automatic SW load depending on sub
version is neccessary.
I'm not sure if that is in scope of a protocol draft or if it should be
described seperately. But keeping the time line of protocol draft and
avoiding delaying ANCP work it may be desirable to identify sections in
protocol draft where notes are useful to detail that issue without changing
sections and order of the document.
From my understanding three sections are concerned. I propose adding the
notes at that sections.
Please see below the identified sections and added notes taken based on
protocol draft 05 for discussion:
Regards Thomas
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Chapter 2 Introduction / page 4:
...
Not all the fields in relevant GSMP messages are used by ANCP. This draft
indicates the value that ANCP should set for the fields in these GSMP
messages.
[T.H.:] Note: Implementations which use GSMP and ANCP conventions before RFC
publication must use sub-version 1.
RFC based implementations must use sub-version 2. For details see chapter 5.
...
------------------------------------------------------------------------------------
Chapter 5. Access Node Control Protocol (ANCP) / page 15
...
The 8-bit version field in the base GSMPv3 message header is split
into two 4 bit fields for carrying the version and a sub-version of
the GSMP protocol. ANCP uses version 3 and sub-version 1 of the GSMP
protocol. An ANCP implementation SHOULD always set the version field
to 3, and the sub-version field to 1. The Result field in the
message header has been modified to be 4 bits long, and the Code
field to be 12 bits long.
Version:
The version number of the GSMP protocol being used in this
session. ANCP uses version 3.
Sub-Version:
The sub-version number of the GSMP protocol being used in this
session. ANCP must use sub-version 2 of the GSMP protocol. [T.H]:Pre RFC
implemtations must use sub-version 1.
---------------------------------------------------------------------
Chapter 5.1. ANCP/TCP connection establishment / Page 19:
...
NAS listens for incoming connections from the access nodes. Port 6068 is
used for TCP connection. Adjacency protocol messages, which are used to
synchronize the NAS and access-nodes and maintain handshakes, are sent after
the TCP connection is established. ANCP messages other than adjacency
protocol messages may be sent only after the adjacency protocol has achieved
synchronization.
[T.H.]:Note: NAS must detect per peer the sub version and must load and
synchronize with appropriate protocol implementation.