The LDAP protocol is often used to exchange system administrative information, as well as phonebook data. Both applications may call for high responsiveness, even over long-distance connections. The SCTP protocol has the best cards for this game.

SCTP [RFC 4960] is a relatively new standard transport protocol that holds a sort of middle ground between TCP and UDP. It communicates frames of data which may be larger than the MTU, and these are reliably delivered by default. Applications choose between in-order delivery and unordered delivery for each frame sent. SCTP connections have parallel streams, each of which is independently ordered.

LDAP [RFC 4511] is generally run over TCP, and has no mapping to UDP. The reason is that the protocol is not designed to deal with loss of packets. The protocol itself however, uses LDAPMessage frames that hold an session identifier, so that the server can respond concurrently to concurrent queries.

Protocol Construction

Read the two RFC’s and get creative — find methods to map LDAP onto SCTP. The question is not whether it is possible, but how many variations can be constructed. For instance, LDAP’s inherent concurrency may be exploited through parallel streams. But care should be taken to retain protocol correctness, while mapping the LDAPMessage frames onto SCTP frames over (multiple?) streams.

During this phase, we will guide you in constructing your mappings, and finding possible alternatives. You should be able to read the quoted RFC’s, but these two are expected to be sufficiently self-contained so that you need not chase reference upon reference of RFC literature.

Testing Performance

Build a simple tunnel program to test the most interesting mappings of LDAP onto SCTP. You can use Python if you like, you can just tune down the performance of the links to match its reduced speed.

Compare the performance of your mappings under simulated stormy networking conditions:

  • Perfect networking conditions

  • Bandwidth nearly fully exploited by other traffic

  • Various packet dropping rates

  • Constant packet re-ordering due to flipping routes

Your report will argue which LDAP-over-SCTP mapping is advised under each of these conditions, in terms of extra network load and in terms of user-experienced responsiveness to queries, that is, packet delay times.

Please conduct your experiments with some care; measure in the middle of a run and over a reasonable period to get a low variability in your results; you can then make your statements with a high level of confidence.