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SNMP is a new pure-Perl SNMP management library that's dramatically faster, simpler to use, and less bug-prone than Net::SNMP, the widely-used pure-Perl SNMP library.

SNMP is also more flexible than Net::SNMP, in that you could use it to build an SNMP agent, SNMP packet dumper, POE component, etc., without rewriting major parts of the code. None of these features are built in yet, except for a skeletal undocumented 87-line SNMP agent implementation used for the regression tests.

However, Net::SNMP is much more mature and presently supports more features, including SNMPv3, traps, the new request types introduced in SNMPv2 (bulk gets and inform requests), nonblocking callback-based operation, OID sorting, robustness against some common bugs in SNMP agent implementations (specifically, sending negative values for unsigned numbers, and circular getNextRequest handling) and (in the easy-to-use SNMP::Simple interface) multiple OIDs per request.

I plan to add all of these features, but the existing featureset actually covers the majority of management-station uses of SNMP I've seen. SNMPv2 is more efficient than SNMPv1, but not as widely supported, and SNMPv2 support is often buggy. Management stations, by definition, don't send SNMP traps or inform-requests. SNMPv3 still isn't widely deployed, despite the absurd security problems SNMPv1 creates. Nonblocking operation is important for some high-performance applications, but harder to use. OID sorting is primarily useful when you're implementing an agent; both this package and Net::SNMP give you back OIDs from walks in sorted order.

That said, this package is about 20% of the size of Net::SNMP, counting non-duplicate lines of B::Deparse'd code in SNMP.pm, SNMP/Simple.pm, and SNMP/Mapper.pm.

On the other hand, the regression tests for Net::SNMP are just over 100 lines (using the same metric), while the regression tests for this module are about 550.
Why would you want to use this module instead of its much-more-mature sibling, Net::SNMP?

Well, usually, you wouldn't. I anticipate that this module will get better in time, but right now, you probably don't want to use it, unless Net::SNMP just doesn't work for you.

Some of the reasons Net::SNMP doesn't work for me follow:

• it's slow. On my 500MHz laptop, Net::SNMP can do about 110 simple request/response pairs per CPU second. These SNMP modules can do about 1100, about as many as ucd-snmp snmpd can respond to. (The SNMP agent in SNMP::Agent is a little faster.)
• it's inconvenient to use for simple cases.
• its interface is bug-prone in a few ways.
  • By default, it does all sorts of translations to make things human-readable, but the translations are sometimes pretty heuristic. This can result in bugs in your code. (For example, it renders OCTET_STRINGs in hexadecimal if they contain any unprintable characters. This (in combination, obviously, with our carelessness) resulted in our software failing to handle MAC addresses correctly if they happened to contain no unprintable characters.
  • You can't do SNMP operations in blocking mode when nonblocking SNMP sessions exist --- that is to say, Perl hasn't destructed them yet. This occasionally catches performance bugs, but it's silly when you're trying to send an SNMP trap, which doesn't block in any case, or when your nonblocking SNMP sessions have merely not yet gone out of scope.
  • Its SNMP walk interface gives you the results of the walk in a hash, so their order is scrobbled. There's another method to get the order of the OIDs, though.
  • With SNMPv2, it often returns error indicators in-band, as the values of OIDs.
• it's completely unhelpful for dissecting captured SNMP packets (say, for debugging) because demultiplexing and decoding logic are closely intertwined, apparently for efficiency.
• it's not suitable for writing SNMP agents, because it discards the types before it hands the data back to you. It also doesn't document a way to receive requests and send responses. (It exists, of course.)
• it's not suitable for making test stubs for systems that speak SNMP, because it does too much on your behalf. For example, you might want to verify that your management station handles negative TIMETICKS values in a sane way, but Net::SNMP won't let you send negative TIMETICKS values. (Net::SNMP does, by default.)
• it has a nonblocking mode, but it insists on using its own event loop, which means you can't integrate it into, say, a POE program.
• it's huge and complicated, and therefore hard to maintain and hard to find bugs in. Net::SNMP 4.1.2's .pm files total 9690 lines, including 4456 distinct lines. These SNMP modules total 712 lines at the moment, including 466 distinct lines. If you use Deparse, Net::SNMP is about 2000 lines, while these SNMP modules are about 400. We had a couple of serious bugs in critical parts of our system that turned out to come from bugs in Net::SNMP, but we only know that because they disappeared when we upgraded to a new version of Net::SNMP that fixed the bugs. I also find the Net::SNMP code hard to read and understand, which may be just a dialect issue; you be the judge. Here's the routine that convinced me I needed to rewrite Net::SNMP instead of trying to hack on it:

        sub debug
        {
           (@_ == 2) ? $DEBUG = ($_[1]) ? TRUE : FALSE : $DEBUG;
        }

That routine exists, in exactly the same form, in Net::SNMP::Security::USM, Net::SNMP::Security::Community, Net::SNMP::MessageProcessing, Net::SNMP::Message, Net::SNMP::Dispatcher, Net::SNMP::Transport::UDP, Net::SNMP::PDU, and Net::SNMP::Security. It is by no means the only code duplicated verbatim between these modules.