RE: iSCSI: Login negotiation space

["Julian Satran" <Julian_Satran@il.ibm.com>]

Pat,

A factor of 10 over what is needed today is what I would call a conservative design.
Limiting the support to 2k would be extremely unwise.
And 16 is a tiny amount of memory - of no concern to software implementation and to most hardware implementations.

Julo

pat_thaler@agilent.com 07/02/2002 01:56 AM Please respond to pat_thaler

To:        Julian Satran/Haifa/IBM@IBMIL         cc:        ips@ece.cmu.edu         Subject:        RE: iSCSI: Login negotiation space

Julian,

4.1 contains a requirement that initiators and targets support receiving at least 16384 bytes of key=value data (when not supporting very long authentication items). This is overkill and is making drivers larger than they need to be. 

My calculations are that Security negotiation using the CHAP method (including the Any-stage keys) takes less than 1600 bytes. Operational negotiation requires 1276 bytes (also including the Any-stage keys). All the operational plus security keys are 1911 bytes.

Therefore an implementation could hold all the necessary keys in 2 Kbytes. And, the implementation doesn't need to keep the security keys after the security negotiation is done so it could clear some of that out to make room for future keys or vendor specific keys. 16 K bytes is about 10 times the necessary storage in that case.

The number of negotiation bytes that a device is required to support should be reduced substantially - preferably to 2048 bytes.

Regards,
Pat


The numbers:

  43                                  AuthMethod
           CHAP keys 
 264                                  Name (no defined size limit - using 255)
  11                                  Algorithm
  11                                  Identifier
 264                                  Challenge
  42                                  Response (for MD5)
_____
 635 Chap negotiation length
 892 Any-stage keys
----
1527

Operational negotiation keys
  24                                  HeaderDigest
  24        DataDigest
  49        MaxConnections
 270                                  TargetName* or InitiatorName*
 271                                  TargetAlias* or InitiatorAlias*
 273        TargetAddress*
  55                                  TargetPortalGroupTag*
  15                                  InitialR2T
  19                                  BidiInitialR2T
  18                                  ImmediateData
  34                                  MaxRecvDataSegmentLength
  24                                  MaxBurstLength
  26                                  FirstBurstLength
  24                                  DefaultTime2Wait
  26                                  DefaultTime2Retain
  25                                  MaxOutstandingR2T
  18                                  DataPDUInOrder
  24                                  DataSequenceInOrder
  24                                  ErrorRecoveryLevel
  23                                  SessionType*
------
 892 Any-stage keys
 384 Not Any-stage
------
1276 Operational keys