What is a Slot/FRU/PhysDevice?
jason@coral.com (Jason Perreault) Mon, 10 August 1992 19:16 UTC
Return-Path: <owner-chassismib>
Received: by CS.UTK.EDU (5.61++/2.8s-UTK) id AA23745; Mon, 10 Aug 92 15:16:23 -0400
Received: from gatekeeper.coral.com by CS.UTK.EDU with SMTP (5.61++/2.8s-UTK) id AA23741; Mon, 10 Aug 92 15:16:17 -0400
Received: from maui.coral.com by gatekeeper.coral.com (4.1/SMI-4.1) id AA00281; Mon, 10 Aug 92 15:16:47 EDT
Received: by maui.coral.com (4.1/SMI-4.1) id AA03682; Mon, 10 Aug 92 15:17:22 EDT
Date: Mon, 10 Aug 1992 15:17:22 -0400
From: jason@coral.com
Message-Id: <9208101917.AA03682@maui.coral.com>
To: chassismib@cs.utk.edu
Subject: What is a Slot/FRU/PhysDevice?
I haven't attended the last two IETFs, and from the minutes I can't determine whether these issues have been raised, so.... I'm wondering whether a distinction needs to be made between "physical device" and "slot", and whether the concept of field-replaceable unit (FRU) needs to be introduced. While the most common interrelationship among physDev-FRU-slot might be 1-1-1, two other cases probably are common enough to warrant some manner of treatment in the MIB: -------------------------------------------------------------------------- MULTIPLE FRUs IN A SLOT (1-many-1) A slot might be occupied by more than one FRU, (eg, front-inserted processing module + rear-inserted cabling interface module), which are separately identifiable products in the vendor's enterprise subtree. The current Slot Table probably would identify only the processing module. Considerations: - need additional FRU index for slot table? - unique index value assigned to each FRU, or just count FRUs starting from 1 for each slot? - unique FRU index values implies migrating module-identifying info to a FRU Table? - some FRUs detectable only when some "primary" FRU installed and running. -------------------------------------------------------------------------- MULTI-SLOT FRU (1-1-many) A FRU, owing to physical construction, might span two or more contiguous slots, although it is regarded as occupying only one of them from a functional standpoint. Considerations: - need to distinguish among slots that are a) physically and functionally occupied, b) physically obstructed but functionally empty, and c) physically empty (unoccupied and unobstructed)? - need to identify specifically which FRU obstructs a slot? - need to distinguish whether a slot is fully, or only partially, obstructed? (Eg single-wide processor FRU in slot N attached to double-wide cable interface FRU in slots N/N+1, is the "orphan" processor receptacle in slot N+1 available)? -------------------------------------------------------------------------- These examples lead me to consider a MIB structure that includes: a) a FRU Table that itemizes and identifies FRUs, and assigns to each a unique index (chasFruIndex); b) a Slot Table indexed by { chasSlotIndex, chasFruIndex } to identify slot/FRU associations. Most of the module-identifying information in the Slot Table migrates to the FRU Table. An enumerated status object is defined for the Slot Table, having values of: other(1), -- not classified by other enum value below; empty(2), -- nothing in this slot, available for use; occupied(3), -- FRU functionally resides in this slot fullyObstructed(4), -- indicated FRU (residing in another slot) -- fully obstructs this slot; partiallyObstructed(5) -- indicated FRU (residing in another slot) -- partially obstructs this slot, ie obstructs -- portion of slot normally "consumed" by this -- FRU type. If the same FRU index appears in different slots, then a multi-slot FRU is indicated, with the status object distinguishing in which slot(s) the FRU is considered to be installed, and which other slots (or portions thereof) are rendered unavailable for use as a consequence of the FRU's physical presence. A definite downside of this MIB structure is that the WHAT and WHERE (FRU type and location) information is distributed across two tables (FRU and Slot) instead of one (as in the current Slot Table). Having made this near-stream-of-consciousness presentation, I'll ask: To what level of detail ought the MIB seek to represent the physical composition of the chassis? ------------------------------------------------------ Jason Perreault net : jason@maui.coral.com Coral Network Corp voice : (508) 460-6010 x228 Marlborough MA 01752 fax : (508) 481-6258
- What is a Slot/FRU/PhysDevice? Jason Perreault
- Re: What is a Slot/FRU/PhysDevice? David Arneson