Inter-entity connections.
{3COM/PDD/PeteW}@pdd.3mail.3com.com Tue, 13 July 1993 13:24 UTC
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Date: Tue, 13 Jul 1993 13:43:00 -0700
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From: {3COM/PDD/PeteW}@pdd.3mail.3com.com
Subject: Inter-entity connections.
To: chassismib@cs.utk.edu
Message-Id: <930713.055544@3Mail.3Com.COM>
Msg-Date: 1993-07-13
Msg-Time: 13:40
Microsoft Mail v3.0 IPM.Microsoft Mail.Note From: Wilson, Peter To: Chassis MIB Subject: Inter-entity connections. Date: 1993-07-13 13:37 Priority: Fixed Font: 0001 Message ID: 24D88EC5 Conversation ID: 24D88EC5 ------------------------------------------------------------------------------ This text proposes one way in which the chassis MIB one resource to one module and one resource to one entity relationships can be maintained but also how the MIB can be enhanced to include information that allows entity interconnection information to be made visible in the MIB. Basically the configuration MIB groups already available are augmented by a interconnection group. The interconnection group contains 'link definitions'. Each link definition describes a connection between two entities in the chassis. I'll describe this by means of an example. Consider a 3 port bridge which has two Ethernet and one 802.5 port. The chassis also contains three other entities, a token ring and two Ethernet. The bridge ports are connected to these entities. Now the configuration groups describe the equipement in the chassis as follows: Discrete equivalent of the chassis configuration. +----------+ | Bridge | +-+--+--+--+ | | | | | +---------------+ +--+--+----+ | | +-+--------+ | +-----+------+ |Repeater 1|<---+ +--->|Repeater 2| +->|Token Ring 1| +----------+ +-+--------+ +-----+------+ The MIB to represent this configuration would be as follows: Module Table: +----------------------------------------------------------+ |location type | instance | Contents OID | Description |...| +==========================================================+ | backplane | 1 | multiServBp | "" | | | modularSlot | 1 | repeaterMod | ".3 RLC..." | | | modularSlot | 2 | repeaterMod | ".3 RLC..." | | | modularSlot | 3 | tokenRingMod| ".5 RLC..." | | | modularSlot | 9 | bridgeMod | "Bridge" | | +--------------+----------+--------------+-------------+---+ Entity Table: Indexed by a unique integer. +----------+-------------+----------------------+---+ |Entity Id | Entity OID | Description |...| +===================================================+ | 1 | repeater | ".3 Rptr B'plane 1" | | | 2 | repeater | ".3 Rptr B'plane 2" | | | 3 | tokenRing | ".5 Token Ring" | | | 4 | bridge | "3 port .3/.5 Bridge"| | +----------+-------------+----------------------+---+ The physical resource table provides information regarding all the resources in the system. It also provides the mapping of resource to module and from resource to entity. The resource table is indexed on location type, instance and a resource number within that module. The location type and instance provide the map to the module table. The assignment column contains the id of the single entity to which this resource is currently assigned. map |<---- map to module ---->| |<-to entity->| +--------------+----------+----------+-------------+--------------+ |location type | instance | Resource | (Entity Id) | Resource OID | +=================================================================+ | backplane | 1 | 1 | 1 | rptrBplane | | backplane | 1 | 2 | 2 | rptrBplane | | backplane | 1 | 3 | 3 | tkBplane | | modularSlot | 1 | 1 | 1 | rptrGroup | | modularSlot | 2 | 1 | 2 | rptrGroup | | modularSlot | 3 | 1 | 3 | trGroup | | modularSlot | 9 | 1 | 1 | rptrPort | | modularSlot | 9 | 2 | 2 | rptrPort | | modularSlot | 9 | 3 | 3 | trPort | | modularSlot | 9 | 4 | 4 | bridge | +--------------+----------+----------+-------------+--------------+ The logical resource table describes the same relationships but using the entity relationship as the SNMP index to provide direct entity to resource mappings. Now with reference to the picture above the MIB so far has not specified the interconnection of entities. It is suggested that this information be kept in a seperate optional MIB group. The new group will provide a 'entity, connected to entity' mapping. There are several ways this information can be maintained, for example resource to resource, entity to resource, resource to entity or straight entity to entity. Consider an entity to entity table. This could simply contain the following information: Link Index from to ------------------------------------------------------ 1 entity 1 connects to entity 4 2 entity 2 connects to entity 4 3 entity 3 connects to entity 4 4 entity 4 connects to entity 1 5 entity 4 connects to entity 2 6 entity 4 connects to entity 3 This is not the most useful way of representing the information. There is no way to ask which entities are connected without reading the whole table. Neither is it possible to say by which resources the entities are connected. Perhaps a better way is to use a resource to resource mapping. This does however create the need to have some additional resources simply to complete the mapping. Consider the bridge card as being described as 7 resources: |<---- map to module ---->| |<-to entity->| +--------------+----------+----------+-------------+--------------+ |location type | instance | Resource | (Entity Id) | Resource OID | +=================================================================+ | ... | ... | ... | ... | ... | | modularSlot | 9 | 1 | 1 | rptrPort | | modularSlot | 9 | 2 | 2 | rptrPort | | modularSlot | 9 | 3 | 3 | trPort | | modularSlot | 9 | 4 | 4 | bridgePort |* | modularSlot | 9 | 5 | 4 | bridgePort |* | modularSlot | 9 | 6 | 4 | bridgePort |* | modularSlot | 9 | 7 | 4 | bridge | +--------------+----------+----------+-------------+--------------+ The bridge ports have been introduced for the purpose of providing a complete mapping. They are not required unless the interconnection information is to be supported. Note that the bridge ports are part of the bridge entity, but that they actually transmit traffic via the .3 and .5 physical ports. Now the interconnection table looks like this: Link Index from resource to resource ------------------------------------------------------ 1 modSlot.4.1 connects to modSlot.4.4 1 modSlot.4.2 connects to modSlot.4.5 1 modSlot.4.3 connects to modSlot.4.6 1 modSlot.4.4 connects to modSlot.4.1 1 modSlot.4.5 connects to modSlot.4.2 1 modSlot.4.6 connects to modSlot.4.3 Note that no other resources need to be present in the mapping table. These are the only inter-entity connections! Note that in the 02 draft, there is now actually 2 ways of describing a resource, either by it's (locType, loc, index) fixed triplet, or by the (entity, resource-subindex) pair. The second description changes will change when a resource is switched from one entity to another. Most of the interconnection relationships are best defined in terms of entity/sub- index. It is the entities that are interconnected, not the modules. THE POINT ========= As discussed at the Columbus meeting, the interconnection information is important but it is too difficult to try to have one set of tables describe everything. It just does not work. The configuration tables should be just that. Interconnection should be represented in a seperate table or group. The recommendation then is to take the fairly stable draft-ietf-chassis- mib-01.txt as the basis of a standard and build on that. Forget the ever more complex overloading of the same tables and the ever more complex and fuzzy definitions of entities, resources and modules. Pete
- Inter-entity connections. {3COM/PDD/PeteW}