Proposed changes to Draft Frame Relay MIB for multiprotocol support.
Alan Bartky <alan@xylan.com> Wed, 03 January 1996 17:22 UTC
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Date: Wed, 03 Jan 1996 08:22:31 -0800
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From: Alan Bartky <alan@xylan.com>
Message-Id: <9601031622.AA05800@irvine.XYLAN.COM>
To: iplpdn@CNRI.Reston.VA.US
Subject: Proposed changes to Draft Frame Relay MIB for multiprotocol support.
Cc: alan@xylan.com
Fellow Mibbers and Mibbettes - In doing a more detailed review of the MIB I would like to address some issues in regards to the latest draft and support for some functions of RFC1490 in the Frame Relay DTE MIB. I currently have two proposed changes. First I'll start with the easy one. In the guidelines of the current drafr of the Frame Relay DTE MIB there are recommendations for supporting RFC1573 ifTable objects. Most routers today support RFC1490 and multiple protocols but not necessarily all defined in RFC1490, FRF.3 or T1.617 Annex G. For a router or other Frame Relay DTE that follows RFC1490 formatting, one of the requirements is to ignore any frames that it doesn't support or understand. It would be usefull for the SNMP agent to use the ifInUnknownProtos to indicate the number of packets discarded due to an unknown or unsupported RFC1490 protocol. For the current draft MIB I propose the following change: Current text (in section 4.1) ifInUnknownProtos Always zero(0) as there is only one protocol (frame relay) and it is always understood. Proposed change: ifInUnknownProtos Number of unknown or unsupported upper layer protocol frames received and discarded. If only a single upper layer protocol is present (i.e. multiprotocol formatting is not used) then this counter would be always zero(0). Second for the more difficult one. The current method of mapping a single logical ifIndex in the frCircuit table will not work in all cases, especially with several protocols being supported in a router which map to different DLCIs where the sharing of DLCIs overlaps. Consider an example where a single central site router is communicating via Frame Relay to a remote IP/IPX router, a remote IP/IPX/Bridging router and a remote bridge. The DLCI mapping for this example is: DLCI 40: VC to a remote router that supports IP and IPX. DLCI 41: VC to a remote router that supports IP, IPX and bridging. DLCI 42: VC to a remote bridge that does not support IP or IPX routing. IPX IP Bridging |\ /| / | | \ / | / | | \/ | / | | /\ | / | | / \ | / | |/ \|/ | 40 41 42 In this case there would have to have 3 logical ifIndex values to support the three logical ports. Having a single ifIndex in the DLCI table is insufficient to support this case. Assuming the mapping for the logical ports needed was IPX: ifIndex.10 IP: ifIndex.11 Bridging: ifIndex.12 Then you would need the following mapping: DLCI 40: ifIndex.10 & ifIndex.11 DLCI 41: ifIndex.10, ifIndex.11 & ifIndex.12 DLCI 42: ifIndex.12 This problem of multiple ifIndex values relating to a lower layer is not new. It was recoginized in RFC1573. The proper way to map this is not from the lower layer looking up, but from the upper layer looking down. In order to solve the problem in the frame relay MIB, I believe we will need to have a new table for DLCI to virtual port mapping. The above example could be accomplished using a table with multiple entries as follows: Table Entry 1: ifIndex.10, DLCI 40 Table Entry 2: ifIndex.10, DLCI 41 Table Entry 3: ifIndex.11, DLCI 40 Table Entry 4: ifIndex.11, DLCI 41 Table Entry 5: ifIndex.12, DLCI 41 Table Entry 6: ifIndex.12, DLCI 42 I am willing to start drafting text on this proposal, but since this is more controversial I'll wait back for some responses first. Let me know what you think. 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 ********************************************************** P.S. If we decide to add either of these changes we should have a references to RFC 1490, FRF.3.1 and T1.617 Annex G at the end of the document.
- Proposed changes to Draft Frame Relay MIB for mul… Alan Bartky
- Re: Proposed changes to Draft Frame Relay MIB for… James Watt
- Re: Proposed changes to Draft Frame Relay MIB for… Andrew G. Malis
- Re: Proposed changes to Draft Frame Relay MIB for… Alan Bartky
- Re: Proposed changes to Draft Frame Relay MIB for… Alan Bartky
- Re: Proposed changes to Draft Frame Relay MIB for… James Watt