How to use TransportAddressIPv4 in conjunction with TransportAddressType as a pair?

Questions / Help
1

With my limited knowledge of SNMP MIB constructs and such, I kindly ask for help in understanding how to approach my problem.

I have today a working solution for configuring an IPv4 address and Port in one object using this:

TransportAddressIPv4 ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "1d.1d.1d.1d:2d"
    STATUS      current
    DESCRIPTION
        "Represents a transport address consisting of an IPv4
         address and a port number (as used for example by UDP,
         TCP and SCTP):

          octets       contents         encoding
           1-4         IPv4 address     network-byte order
           5-6         port number      network-byte order

         This textual convention SHOULD NOT be used directly in object
         definitions since it restricts addresses to a specific format.
         However, if it is used, it MAY be used either on its own or
         **in conjunction with TransportAddressType** or TransportDomain
         **as a pair.**"
    SYNTAX      OCTET STRING (SIZE (6))

Now I need to extend this object to also include IPv6 and Dns as choices and the description of TransportAddressIPv4 implies that there should be a way to combine it with TransportAddressType as a pair. How would that be done? I can’t find anything in any RFC nor elsewhere that does this…

2

This is from TRANSPORT-ADDRESS-MIB.mib:

TransportAddressIPv6 ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "0a[2x:2x:2x:2x:2x:2x:2x:2x]0a:2d"
    STATUS      current
    DESCRIPTION
        "Represents a transport address consisting of an IPv6
         address and a port number (as used for example by UDP,
         TCP and SCTP):

          octets       contents         encoding
           1-16        IPv6 address     network-byte order
          17-18        port number      network-byte order

         This textual convention SHOULD NOT be used directly in object
         definitions since it restricts addresses to a specific format.
         However, if it is used, it MAY be used either on its own or
         in conjunction with TransportAddressType or TransportDomain
         as a pair."
    SYNTAX      OCTET STRING (SIZE (18))
3

Some clarification from my side, I have this object, which is limited to IPv4 addresses.

myAddress OBJECT-TYPE
    SYNTAX      TransportAddressIPv4
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
        "IPv4 address and Port.
        "
    ::= { myObject 2 }

…and now I’d like to replace TransportAddressIPv4 in this object with a pair, using TransportAddressType in some way. I suppose that it would be going together with the general definition TransportAddress (I also don’t know how to do that), but how could I also include the specific TransportAddressIPv4, TransportAddressIPv6 and TransportAddressDns as choices in order to benefit from e.g. the DISPLAY-HINTs in those TEXTUAL-CONVENTIONs?

4

You could try with two entries: One with TransportAddressType and the other with
TransportAddress (the “base type” for all addresses). Or combine them into one
with a SEQUENCE:

myTransport OBJECT-TYPE
    SYNTAX     MyTransport
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "BLA BLA BLA."
    ::= { myObject 8 }

MyTransport ::= SEQUENCE {
    type   TransportAddressType,
    addr   TransportAddress
}

Or you could create your own using the CHOICE construct.
I could not find any good examples of CHOICE with a quick web search.

5

Unfortunately compilation of the SEQUENCE example fails:

% rebar3 compile              
===> Verifying dependencies...
===> Analyzing applications...
MY-MIB.mib: 709: Undefined type ''MyTransport''
[MY-MIB.mib:731][WAR]: Unexpected SEQUENCE 'MyTransport' => ignoring

I suppose I could use that construction if I just can get it to compile, but in any case I’d prefer a solution using CHOICE. I have also not been able to find any examples with the CHOICE construct. Anyone else…?