Subject: RE: draft-ietf-hubmib-etherif-mib-v2-02.txt

From: "Kubinec, Lynn" <[email-masked]>
Date: Mon, 1 Feb 1999 12:11:01 -0600

Hi all,

I received a question regarding one of the MIB objects in
the etherif MIB.  I can't answer it, so I'm looking to the
group for help.  The object is the dot3PauseLinkDelayAllowance.

Anyone have any idea what this REALLY is?  Is it the pause quanta
multiplied by 512?

I've checked the 1998 version of IEEE 802.3 which includes 
802.3x and y (1997).  The only reference to LinkDelayAllowance
is in the management section (30.3.4.1).  In the Annex (31B),
the Pause function's parameter is pause quanta.

Any enlightenment greatly appreciated.  Thanks!

Lynn

> 
>        dot3PauseLinkDelayAllowance OBJECT-TYPE
>            SYNTAX      Unsigned32 (0..4294967295)
>            MAX-ACCESS  read-write
>            STATUS      current
>            DESCRIPTION "The allowance, in bit times, made by the PAUSE
>                        MAC Control entity for round-trip propagation
>                        delay of the full-duplex link."
>            REFERENCE   "[IEEE 802.3 Std.], 30.3.4.1,
>                        aPAUSELinkDelayAllowance."
>            ::= { dot3PauseEntry 3 }

---

From: John Flick <[email-masked]>
Date: Mon, 1 Feb 1999 12:33:01 -0800 (PST)

> Any enlightenment greatly appreciated.  Thanks!

The only mention of the link delay allowance in the Annex is at the
end of 31B.3.7:

    "In addition to DTE and MAC Control delays, system designers
    should take into accoutn the delay of the link segment when
    designing devices that implement the PAUSE operation (see Clause
    29)." 

Tables in clause 29 have maximum round trip delay bit times for
various types of cabling.  Clause 42 has similar information for
Gigabit.

The annex doesn't specifically say how the pause function is supposed
to use this information, or why it may be interesting from a
management point of view.  I'll let Dan handle that, since he was the
one arguing to keep this object when I wanted to nuke it :-)

John