Subject: AAP: Chattiness of protocol

From: Thomas Narten <[email-masked]>
Date: Mon, 21 Aug 2000 16:08:27 -0400

This protocol seems fairly "chatty" to me, and I wonder how well it
will scale in practice.

Things to note:

0) All MAAS messages are multicast to a multicast group, so they are
   transmitted throughout a administrative network.

1) All MAASes send periodic multicast AIU messages every 30
   seconds. This is to cover the entire state of the Allocation
   Record (I believe).

2) Whenever a MAAS allocates an address (e.g., from its preallocated
   set), it immediately sends out an AIU for those addresses,
   following up with retransmissions for reliability.

3) For non-preallocated addresses, a MAAS sends sequence of ACLM
   messages (including retransmissions for reliability) when a request
   to allocate an address is made.

Result: for a moderately large site, it seems like the protocol could
generate quite a lot of traffic. This especially true if a large
number of addresses are allocated. I have concerns as to how large an
environment this will scale to.

Given the time scales involved (shouldn't addresses be allocated for
relatively long periods of time?), it seems like the protocol could
relax some of its timing constraints, especially with regards to
periodic multicast. Or to delay sending out AIU for pre-allocated
addresses in order to batch them up.

It also seems like the model could do more to encourage
pre-allocation, so that becomes the normal way to assign
addresses. Right now, I don't read the spec as suggesting this is
required.

Finally, what size of environment is this protocol expected to scale
to? Is their consensus that the protocol will do so?

Thomas