Subject: AAP discussion topics

From: Steve Hanna <[email-masked]>
Date: Tue, 13 Jul 1999 14:01:29 +0-200

For Thursday's MALLOC meeting, we have scheduled time for "AAP Discussion"
Here is a list of topics I would like to cover. I would like to settle these
'big-picture' topics first. We can work out minor changes to packet formats
and such later.

If there are other 'big-picture' topics that we should discuss, please let
me know. Also, feel free to discuss these topics and others on the list as
well. Especially those who weren't able to make it to Oslo.

Thanks,

Steve

P.S. This discussion pertains to draft-ietf-malloc-aap-01.txt.

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* Should we include failover support in AAP? If so, what form should it take.
  By failover, I mean the ability to have one MAAS fail and have another take
  over seamlessly (able to extend leases allocated by the first, etc.).

  I suggest that we not include failover support in the current version of AAP.
  Doing failover will require sending per-lease information from each server
  to one or more backup servers, ensuring that the backup servers know when the
  primary server goes offline (and that the primary server knows if communications
  to the backup servers is lost), ensuring that the primary and backup servers
  operate in a safe mode while communications are down (since they might both
  still be operating, but with a network partition), and resynchronizing when
  communications are reestablished. Adding all of these features to AAP will
  take a good deal of time and delay the standardization of an important
  protocol.

  For now, MAAS's that need to implement failover can do so using other
  techniques (such as proprietary failover protocols). Eventually, we can come
  back and standardize a MAAS failover protocol, basing it on AAP if we like.

  This approach is analogous to the DHCP approach: standardize the base protocol,
  then develop failover support later.

  Even without failover support, we can still prevent allocation clashes in the
  face of network partition by having AAP servers defend each others' allocations.
  This is described in the current spec.

* Do we need to provide support for MADCAP's Server Mobility in the current AAP
  spec?

  Providing support for Server Mobility will require support quite similar to that
  required for failover. MAAS's will need to communicate per-lease information to
  each other, ensure consistency among each other, detect loss of communication,
  and have a fail-safe mode that they enter when communication is lost, to ensure
  that they do not cause clashes.

  Again, I suggest that we omit this support at this time. Adding it will add a
  lot of complexity to AAP and slow down its development. For now, Server Mobility
  should be supported via other techniques (such as proprietary protocols). Later,
  a standard protocol for this purpose can be developed.

* How can we best use preallocation to support our architecture?

  Preallocation can be used to improve timeliness and efficiency of MAAS operation,
  as well as providing safe operation during network partition. I'll give a more
  detailed explanation during the AAP discussion on Thursday.