Quick Reconnect IETF #61, Lemonade

Overview Minimize resynchronization time to prevent long client locks on mobile terminals. Minimize bandwidth consumption on resource restricted networks (cell). Increase usability of mobile terminals in unstable and resource constricted network environments.

Modified Extensions LOGIN –New Optional NEWSID/SID parameter –Allows the creation of a resumable session. –SID resumes previously created session. AUTHENTICATE –New Optional NEWSID/SID parameter –Allows the creation of a resumable session. –SID resumes previously created session. –Issue with ability to jam unsolicited responses in before the OK response. LOGOUT –New OPTIONAL PRESERVE parameter. –Tells the server not to drop the SID on LOGOUT. EXPUNGED response –Reports list of UIDs which have been permanently removed from the folder.

The SID Parameter The new SID parameter is added to LOGIN and AUTHENTICATE to indicate the resumption of an old session. There are four arguments: –Session Identifier (REQUIRED) –UIDVALIDITY (OPTIONAL) –Last Mod Sequence (OPTIONAL) –Known UIDs (OPTIONAL)

SID processing sequence SID UDIVALIDITY Last Mod Seq UIDs Is SID Valid? UIDVALIDITY Matches? Mod Seq Given? UIDs List? No Flags or Expunges sent. Client will synchronize manually. NEWSID No Flags for list of UIDs & expunged messages Flags for all messages since last mod seq & expunged messages Yes No NOTE: Still open issue.

Issues Server side state cache –Does the server need to store state for a session? –Can the client give enough information on reconnect to tell the server what to do? Number of Sessions per user (account) –Currently MINIMUM set to 5 (randomly selected number). –Can MAXIMUM be set to infinity? Timeout –What is the min/max value? –Should the server advertise max? CONDSTORE –Add separate extension to allow the reporting of expunged messages on SELECT.