On 2/5/07, Quayle, Bill <[EMAIL PROTECTED]> wrote:
I need to implement multicast for server-server FOG communication, but I can't seem to find specifics in the docs. Does anyone have any pointers on how to set this up? In particular, the value for multicastTTL - I'll be traversing numerous routers - should I start with a relatively high TTL value & back it off?
Set it to one greater than the maximum number of routers that a packet will have to pass through on the way between the two furthest-separated members of the group. If you want to be totally precise then each host could have its own specific value, equal to one greater than the number of routers that packets from that host need to traverse in order to reach the most distant member of the group. Setting it higher than that shouldn't cause any damage but it will spread the traffic further than it needs to go. Setting it too low will prevent the packets from reaching the most distant members of the group, which means that the group won't be able to correctly locate existing sessions or properly load-balance the placement of new sessions. 'utgstatus' will show you the list of hosts whose packets have reached this one.
The man page for auth.props notes all multicast params "UNSUPPORTED" - am I treading untested territory here?
Pasting from <http://www.filibeto.org/pipermail/sunray-users/2005-July/001173.html>: ! > Servers are one different subnets from each other ! ! Officially that's an unsupported configuration. Hosts belonging ! to the same failover group are supposed to have at least one subnet ! in common. ! ... ! The reason for the requirement that group members share at least ! one subnet in common is that sadly it's still not unusual, after ! all this time, for some networking gear to not do the right thing ! with multicast traffic. Sometimes it doesn't work in the first ! place, sometimes it works fine for a while and then stops for no ! good reason. If the servers share a common subnet then as a last ! resort you can reconfigure them ('enableMulticast' in auth.props) ! to send their group-membership announcements as broadcasts rather ! than multicasts. If they don't share a common subnet then you ! have no choice but to depend on cross-subnet multicasts working ! in order for failover groups to work. That can be a fragile ! situation. There's more background in that message. OttoM. __ ottomeister Disclaimer: These are my opinions. I do not speak for my employer. _______________________________________________ SunRay-Users mailing list [email protected] http://www.filibeto.org/mailman/listinfo/sunray-users
