Re: Multicast in draft version 5 comments
Alan Bartky <alan@xylan.com> Thu, 04 January 1996 19:11 UTC
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Date: Thu, 04 Jan 1996 10:34:07 -0800
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From: Alan Bartky <alan@xylan.com>
Message-Id: <9601041834.AA08384@irvine.XYLAN.COM>
To: kzm@cisco.com
Subject: Re: Multicast in draft version 5 comments
Cc: james@newbridge.com, cbrown@baynetworks.com, iplpdn@CNRI.Reston.VA.US, alan@xylan.com
Keith - I have read your response and also review RFC 1442 and reviewed previous work in other MIBs (particualary RFC 1747 which I co-authored). As far as the use of read-write versus read-create, I have never quite understood when to use one versus the other. I do know that we published RFC 1747 with read-write objects that had DEFVAL clauses for them. In the SDLC MIB we did this for all objects related to the SDLC port level. The port level table did not have a RowStatus object and was therefore note createable via SNMP. The SDLC Link Station Level did have a RowStatus object, and all "writeable" objects had read-create with a DEFVAL clause. Although I was not directly involved in the "SNMP Details" in editing the RFC, my recollection was that objects at the port level were read-write since the port level table for SDLC could not be "created", whereas the link station table entries had to be created by the SNMP manager since SDLC link stations had to be configured and could not be learned via the network (certanly the case for primary SDLC which initiates the polling). In the SDLC MIB we had DEFVAL for both read-write and read-create objects. If this is not valid, then it made it all the way through the RFC process without being corrected. When we were drafting the MIB, we felt it very important for the agent and the manager to have proper default values to insure proper operation and interoperability of the protocol. This is why we had DEFVALs for every protocol specific read-write and read-create objects. As far as the current draft of the Frame Relay MIB is concerned it has no read-create objects, and it has many read-write objects with DEFVALs defined. It also has RowStatus defined for both the port level (frDlcmi) and for the virtual circuit level (frCircuit). It also has the additional complexity of a virtual circuit either learned automatically from the network (dynamic type, where the row must created by the SNMP agent) or configured by a user (static type, where the row is created using Row Creation and SNMP Set commands). It appears as though at a minimum the frCircuit table objects that are currently all read-write, should be changed to read-create (although since I am not an SNMP V2 syntax expert this may obviously not be correct). If that were true than the object should be changed to: frCircuitMulticast OBJECT-TYPE SYNTAX INTEGER { unicast (1), oneWay (2), twoWay (3), nWay (4) } MAX-ACCESS read-create STATUS current DESCRIPTION "This indicates whether this VC is used as a unicast VC (i.e. not multicast) or the type of multicast service subscribed to" REFERENCE "Frame Relay PVC Multicast Service and Protocol Description Implementation: FRF.7 Frame Relay Forum Technical Committe October 21, 1994" DEFVAL {unicast} -- the default value of frCircuitMulticast is -- "unicast" (not a multicast VC). ::= { frCircuitEntry 15 } Other objects in the frCircuit table that are read-write, have DEFVAL defined and may have to get changed to read-create are: frCircuitState frCircuitCommittedBurst frCircuitThroughput Entries defined in the frDlcmi table that are read-write, have DEFVAL defined and may have to get changed to read-create are: frDlcmiPollingInterval frDlcmiFullEnquiryInterval frDlcmiErrorThreshold frDlcmiMonitoredEvents In summary, it looks like the MIB could use a good "going over" by someone more knowledgeable about the details of SNMP V2 syntax and conventions. Regards, Alan ********************************************************** Alan K. Bartky Email:alan@xylan.com Principal Software Engineer XYLAN Corporation Voice:(714) 597-8042 15707 ROCKFIELD BLVD STE 155F FAX: (714) 597-8342 IRVINE CA 92718-2830 ********************************************************** Excerpt from my original message and Keith's response is below: > > frCircuitMulticast OBJECT-TYPE > > SYNTAX INTEGER { > > unicast (1), > > oneWay (2), > > twoWay (3), > > nWay (4) > > } > > MAX-ACCESS read-write > > STATUS current > > DESCRIPTION > > "This indicates whether this VC is used as a unicast > > VC (i.e. not multicast) or the type of multicast > > service subscribed to" > > REFERENCE > > "Frame Relay PVC Multicast Service and Protocol > > Description Implementation: FRF.7 > > Frame Relay Forum Technical Committe > > October 21, 1994" > > DEFVAL {1} -- the default value of frCircuitMulticast is > > -- "unicast" (not a multicast VC). > > ::= { frCircuitEntry 15 } > > On the usage of DEFVAL, RFC 1442 says: > > 7.9. Mapping of the DEFVAL clause > > The DEFVAL clause, which need not be present, defines an > acceptable default value which may be used at the discretion > of a SNMPv2 entity acting in an agent role when an object > instance is created. > > Note that it is specified for usage when an instance is *created* via > SNMP. Thus, DEFVAL is only appropriate when the MAX-ACCESS clause is > read-create. For read-only/read-write objects, any mention of a default > value should go in the DESCRIPTION clause. > > Keith. >
- Re: Multicast in draft version 5 comments Alan Bartky
- Multicast in draft version 5 comments Alan Bartky
- Re: Multicast in draft version 5 comments Caralyn Brown
- Re: Multicast in draft version 5 comments James Watt
- Re: Multicast in draft version 5 comments Fred Baker
- Re: Multicast in draft version 5 comments Keith McCloghrie
- Re: Multicast in draft version 5 comments James Watt
- Re: Multicast in draft version 5 comments James Watt
- Re: Multicast in draft version 5 comments Caralyn Brown
- Re: Multicast in draft version 5 comments Alan Bartky
- Re: Multicast in draft version 5 comments Fred Baker
- Re: Multicast in draft version 5 comments Keith McCloghrie
- Re: Multicast in draft version 5 comments Alan Bartky
- Re: Multicast in draft version 5 comments Fred Baker
- Re: Multicast in draft version 5 comments Keith McCloghrie
- Re: Multicast in draft version 5 comments Keith McCloghrie