Subject: [MIB-DOCTORS] ifTypes and X25

From: "Wijnen, Bert (Bert)" <[email-masked]>
Date: Fri, 4 Aug 2006 16:24:20 +0200

Keith responded:
> > > 2. The reference for ddnX25(4) and rfc877x25(5) is RFC 1382, 
> > > which says:
> > > 
> > >           -- ifType: ddn-x25 or rfc877-x25
> > >           --      an interface of type ddn-x25 will use an algorithm to
> > >           --      translate between X.121 address and IP addresses.
> > >           --      An interface of type rfc877-x25 will use a
> > >           --      configuration table to translate between X.121
> > >           --      addresses and IP addresses.
> > 
> > So does that mean that for both, the MIB OID is transmission.5 and 
> > the MIB for both is RFC1382-MIB?
> > I believe so, but want to check/verify first, before I add it to the table.
> 
> Yes, and also:
> 
>   miox25(38) -- RFC 1461 & 1382

mmm RFc1461 seems to claim (in my reading) that the ifType is not miox25
but either ddnX25 or rfc877x25 (well actually it says ddn-x25 or rfc877-x25):

   3.2.  Structure of MIB objects

   The objects of this MIB are organized into three tables:  the
   mioxPleTable, the mioxPeerTable, and the mioxPeerEncTable.  All
   objects in all tables are mandatory for conformance with this MIB.

   The mioxPleTable defines information relative to an interface used to
   carry Multiprotocol Interconnect traffic over X.25.  Such interfaces
   are identified by an ifType object in the Internet-standard MIB [4]
   of ddn-x25 or rfc877-x25.  Interfaces of type ddn-x25 have a self
   contained algorithm for translating between IP addresses and X.121
   addresses.  Interfaces of type rfc877-x25 do not have such an
   algorithm.  Note that not all X.25 Interfaces will be used to carry
   Multiprotocol Interconnect traffic. Those interfaces not carrying
   such traffic will not have entries in the mioxPleTable.  The entries
   in the mioxPleTable are only for interfaces that do carry
   Multiprotocol Interconnect traffic over X.25.  Entries in the
   mioxPleTable are indexed by ifIndex to make it easy to find the
   mioxPleTable entry for an interface.

   The mioxPeerTable contains information needed to contact an X.25 Peer
   to exchange packets.  This includes information such as the X.121
   address of the peer and a pointer to the X.25 call parameters needed
   to place the call.  The instance identifiers used for the objects in
   this table are independent of any interface or other tables defined
   outside this MIB.  This table contains the ifIndex value of the X.25
   interface to use to call a peer.

   The mioxPeerEncTable contains information about the encapsulation
   type used to communicate with a peer.  This table is an extension of
   the mioxPeerTable in its instance identification. Each entry in the
   mioxPeerTable may have zero or more entries in this table.  This
   table will not have any entries that do not have correspondent
   entries in mioxPeerTable.

The MIB however is MIOX25-MIB and it also requires the RFC1382-MIB
But do we want to list both MIB modules for the miox25 entry in our
references? In that case we probably also need to include IF-MIB, because
that one is also needed ... ? So I am inclined to have an entry that
says

      <!--label-->     <c>miox25</c>
      <!--ifType-->    <c>38</c>
      <!--MIBoid-->    <c>transmission.38</c>
      <!--MIBmodule--> <c>MIOX25-MIB</c>
      <!--Reference--> <c><xref target='RFCR1461'/></c>
      <!--comment-->   <c>Multiprotocol Interconnect over X.25</c>

If we feel it helps, I could change the comment to:

      <!--comment-->   <c>Multiprotocol Interconnect over X.25
                          Also requires RFC1382-MIB as per
                          <xref target='RFCR1461'/>
                       </c>

>   x25ple(40)  -- RFC 1382

Pretty strange stuff (from before I was looking at content of MIB documents)
Here what I see in RFC2127:

   3.4.4.  X.25 based packet-mode service in B and D channels

   X.25 based packet mode service over B channels can be handled using
   the Dial Control MIB by creating an appropriate peer entry.  The peer
   entry ifType can then be x25(5), thus providing access to X.25
   service.
   X.25 based packet mode service over D channels can be handled by
   creating an ifEndpointTable entry with an isdnEndpointIfType of
   x25ple(40).  The upper protocol layers can then be attached to this
   interface using the ifStack table.

So it talks about ifType x25(5) !!?? which should read: rfc877X25
(another erratum!?) In that case, I guess the RFC1382-MIB must be
implemented as well?

For x25ple(40), I am not sure where/if ifEndpointTable exists!??
Do they mean the isdnEndpointTable which is included in the ISDN-MIB
in RFC2127? (I.e. another erratum !?)

Looking at the isdnEndpointTable, it seems they are saying:

  - the ifType in the ifTable is rfc877X25
  - the ifType in the isdnEndpointTable is x25ple

Did I interpret that correctly?
Possibly the ifType in ifTable can also be ddnX25 ??

By the way, RFC2127 (the only place where I could find the string x25ple)
does not even reference RFC1382.

SO I am inclined to put this in the table:

      <!--label-->     <c>x25ple</c>
      <!--ifType-->    <c>40</c>
      <!--MIBoid-->    <c>transmission.20</c>
      <!--MIBmodule--> <c>ISDN-MIB</c>
      <!--Reference--> <c><xref target='RFCR2127'/></c>
      <!--comment-->   <c>Terminal Endpoint for X.25 based packet mode services.
                         <vspace blankLines='0' />
                          Also requires RFC1382-MIB as per
                          <xref target='RFCR2127'/>
                       </c>

Wow... to get this all sorted out seems much more work then I thought 
Is it worth it?

> and perhaps also for:
>   x25mlp(121)
>   x25huntGroup(122)

Any idea where I can get more info?
I can't find these strings in any MIB module nor in any RFC.
Trying to find details via Google has not resulted in any help yet.
Too many hits...

This is what I have recorded for now:

      <!--label-->     <c>x25mlp</c>
      <!--ifType-->    <c>121</c>
      <!--MIBoid-->    <c>none known</c>
      <!--MIBmodule--> <c>none known</c>
      <!--Reference--> <c>none known</c>
      <!--comment-->   <c>Multi-Link Protocol</c>

      <!--label-->     <c>x25huntGroup</c>
      <!--ifType-->    <c>122</c>
      <!--MIBoid-->    <c>none known</c>
      <!--MIBmodule--> <c>none known</c>
      <!--Reference--> <c>none known</c>
      <!--comment-->   <c>X25 Hunt Group</c>

Bert

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