OpenSLP vs. NetWare's SLP

The purpose of this document is to provide an official Novell answer to prevalent rumours about OpenSLP and NetWare SLP.

Rumors:
Open SLP and NetWare SLP are incompatible.
- This is false.
- They are both compliant with RFC2165.
- They both store services in their cache and answer queries from their cache.

OpenSLP is unusable because it takes over an hour for services to repopulate after a restart of the SLP daemon.
- This is a false statement because it implies that OpenSLP is the reason for the hour delay.
- OpenSLP is not responsible for the individual service re-registration time intervals.
- The application that provides the service is responsible for the re-registration time interval of it's own services.
- That application detemined re-registration time interval will be the same regardless of the type of DA used.
- If the OpenSLP service is restarted on a DA, that DA will advertise itself as a DA via SLP Multicast packets.  All service providers on the same subnet will see that DA advertisement and register services right away.  Service providers on other subnets will reregister their services on their next re-registration interval as determined by the service provider (Example: eDir). The re-registration is NOT determined by OpenSLP!

eDir registered it's services with NetWare DA's quickly but with OpenSLP DA's takes hours?
- This is false
- eDir does not know what kind of DA the SA is talking to.  eDir just registers it's service with it's own SA and that SA sends that service to the DA.
- eDir 8.7.3 re-registers it's services (Bindery and NDAP) every ~9 minutes.
- eDir 8.8.2 and later re-registers it's services (Bindery and NDAP) every hour.
- eDir 8.8.2, 3, and 4 do not have a way to adjust this 1 hour timer.
- eDir 8.8.5 has a way to change the reregistration timer back to 9 minutes, or another value. (See TID#7001449)
- In production 9 minutes has proven to be a very good starting point when adjusting this value. 
- This is an eDir re-registration issue NOT and OpenSLP issue.

OpenSLP DA's and NetWare SLP DA's cannot be configured to run in the same environment at the same time.
- This is false.
- They can be run in the same environment at the same time.

Open SLP DA's and NetWare SLP DA's cannot service the same scope.
- This is false assuming that what is meant is scope name.
- They can service the same scope name.
- As long as all service providers register with both DA's and the Open SLP DA has not recently been restarted both DA's servicing the same scope name should have the same list of services in their respective scope.

NetWare SLP DA's shared service information with each other.
- This is false for both NetWare DA's and OpenSLP DA's.
- Services registered with one DA are not forwarded on by that DA to another DA servicing the same scope name over the SLP protocol.
- On NetWare services are placed in cache just like they are with OpenSLP, however the services are also placed in a scope container in eDir.  Other NetWare DA's servicing the same scope will be notified by eDir of a change to information in eDir and will read the new information from eDir and update their cache.  The DA's did not talk to each other.  The SLP protocol has no mechanism for DA to DA sharing of information.  The synchronisation of service information was provided by eDir synchronisation.

It is incorrect to configure your DA to point to itself.
- This is false
- It is unnecessary to configure your DA to point to itself. because the SA and the UA will use the loopback address to communicate with the DA.
- Adding the DA's own bound IP address to the list of DA's IP addresses on either NetWare or OpenSLP does not cause any problems.  It does cause a duplication of work as the loopback address will also always be used.

OpenSLP cannot do "Scope Filtering" (Registering only some services in a scope.)
- This is true.
- Scope Filtering is something that Novell came up with and implemented on their own.
- The SLP protocol does not provide this Novell only feature.
- With OpenSLP, like on NetWare, you can use more than one scope but all services are registered, deregistered, and retrieved from each scope in the list.  In other words the "Scope List" is for all three services.  (DA, SA, and UA)
- That means that with OpenSLP the DA services all of the scopes in the scope list.
- It also means that the SA registers all services in all scopes in the scope list.
- It also means that the UA will query for services in all of the scopes in the scope list.

Defect# 533432 - In a mixed NetWare DA / OpenSLP DA environment the Open SLP DA can start out seeing itself and the NetWare DA as DA's and then later loose itself as a DA resulting in an inability to respond to certain queries.  At the time of this writing the fix was being verified and will be released in the update channel.