RE: A question regarding draft-itef-ccamp-lmp-01.txt

["Robin Qiu" <robin_qiu@hotmail.com>]

My interpretations (plus more questions) below. Please feedback if you don't 
agree.

Robin Qiu

-----Original Message-----
From: Fugui Wang [mailto:fwang@axiowave.com]
Sent: Thursday, November 08, 2001 3:09 PM
To: 'ccamp@ops.ietf.org'
Subject: FW: A question regarding draft-itef-ccamp-lmp-01.txt


Hi,

I posted this message about a week ago. Could somebody
please give me a clarification about it?

Thanks a lot,
Fugui



-----Original Message-----
From: Fugui Wang
Sent: Wednesday, October 31, 2001 1:09 PM
To: 'ccamp@ops.ietf.org'
Subject: A question regarding draft-itef-ccamp-lmp-01.txt


A question regarding draft-itef-ccamp-lmp-01.txt
In section 13.16 CONFIG_ERROR [page 60]:

o    CONFIG_ERROR, C-Type = 1

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                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         The following bit-values are defined:
         0x01 = Unacceptable non-negotiable CONFIG parameter
         0x02 = Renegotiate CONFIG parameter
         0x04 = Bad Received CCID

Question:
(1) In which situation should you have error code
0x04 = Bad Received CCID? Since the Config message only
bring LOCAL_CCID, the only case I can imagine is that when the
LOCAL_ID in Config doesn't match the lmpRemoteCcId field of
the receiving node. But in this case, shouldn't we just update the
lmpRemoteCcId field (learning remote CCId) instead of sending a
ConfigNack with error code = 0x04?
[Robin] I regard zero CCID as an error. The spec also requires that CCID is 
unique within the NODEID scope. Should the receiver of the Config message 
check this? For in-fiber signaling, the CCID must be the same as the 
interface ID. Should this be validated as well?

(2) For error code 0x01 and 0x02, the N bit in the Config object
of ConfigNack already tells about which error it is (The previous
draft use the N bit in HelloConfig TLV to handle this).
Is it necessary to have an additional ERROR_CODE object in the
ConfigNack? I think the ERROR_CODE is redundant to the N bit
in Config object.
[Robin] The Config object is not always in the ConfigNack message. Even if 
it is, it might just be a copy of the original one contained in the  
received Config message (see 12.4.3), in which case the N bit indicates the 
Config sender's information.

Thanks,
Fugui


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