[Bugs] #3748 untriaged UNSP: Presence not updated, when client disconencts from telepathy-salut

[Sugar Labs Bugs]

#3748: Presence not updated, when client disconencts from telepathy-salut
------------------------------------------+---------------------------------
    Reporter:  ajay_garg                  |          Owner:                             
        Type:  defect                     |         Status:  new                        
    Priority:  Unspecified by Maintainer  |      Milestone:  Unspecified by Release Team
   Component:  untriaged                  |        Version:  Unspecified                
    Severity:  Unspecified                |       Keywords:                             
Distribution:  Unspecified                |   Status_field:  Unconfirmed                
------------------------------------------+---------------------------------

Comment(by ajay_garg):

 This required patching Avahi.

 F14-patched rpms available at ::
 http://people.sugarlabs.org/ajay/root/freedesktop_bug_51501/RPMS/

 If required, corresponding F17 patches maybe generated easily, via
 "customize-avahi-default-ttl-values.patch" patch available in the source-
 rpm at http://people.sugarlabs.org/ajay/root/freedesktop_bug_51501/SRPM/





 Please refer https://bugs.freedesktop.org/show_bug.cgi?id=51501

 History ::
 ===========

 As pointed out by Simon McVittie in
 https://bugs.freedesktop.org/show_bug.cgi?id=51501#c4,
 https://tools.ietf.org/html/draft-cheshire-dnsext-
 multicastdns-15#section-10
 suggests that the Time-To-Live (TT) of the mDNS record is likely to be 120
 seconds.

 However, for all purposes, in whatever testing I came across Avahi, the
 TTL in effect was
 75 minutes , which seemed a bit too late a notification of buddy-going-
 disconnected.



 Fix ::
 ======
 Decrease the Time-To-Live (TTL).



 Solution ::
 ===========

 Obviously, the easiest solution is to set the appropriate values in
                   #define AVAHI_DEFAULT_TTL_HOST_NAME
                   #define AVAHI_DEFAULT_TTL

 However, this has the following caveats ::

 (i)
 It needs a re-compilation/re-packaging of avahi rpms, for every
 change in the values. This is a major deployment headache.

 (ii)
 Also, there is no ideal "TTL" values.

 The lesses the TTL values, more frequent multicast DNS packets will be
 exchanged
 between a pair of peers, thus leading to more traffic.

 However, too large a TTL value, would mean that the peer gets too late a
 notification
 of the buddy going disconnected.

 Thus, ideal values can only be found out by testing in real-field.
 This requires easy configuration of the TTL values, without needing to
 re-compile the rpms.



 Solution-Implementation ::
 ==========================

 The cutomized TTL values will be read during "avahi-daemon" startup.

 1.
 AVAHI_DEFAULT_TTL_HOST_NAME will be set to the value, contained in the
 file "/etc/avahi/avahi-default-ttl-host-name.conf".

 Default value is the same as before, i.e. 120 (seconds).


 2.
 AVAHI_DEFAULT_TTL will be set to the value, contained in the
 file "/etc/avahi/avahi-default-ttl.conf".

 Default value is the same as before, i.e. 4500 (seconds), which is equal
 to
 75 minutes.



 How to customize ::
 ===================

 a)
 "sudo service avahi-daemon stop"

 b)
 Change the values in the corresponding conf files.

 c)
 "sudo service avahi-daemon start"




 AUTHOR: Ajay Garg <ajay at activitycentral.com>


 Thanks to ::

     Will Thompson    <will.thompson at collabora.co.uk>
     Simon McVittie   <simon.mcvittie at collabora.co.uk>
     Xavier Claessens <xclaesse at gmail.com>

-- 
Ticket URL: <http://bugs.sugarlabs.org/ticket/3748#comment:1>
Sugar Labs <http://sugarlabs.org/>
Sugar Labs bug tracking system