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From Rohit Yadav <rohit.ya...@citrix.com>
Subject Ideas for virtual Redundant Router
Date Thu, 16 Aug 2012 09:41:37 GMT
Hi,

At present the redundancy of the virtual redundant routers, VRRP [3], operates outside the
scope of CloudStack [2]. And any event that happens outside of CS, like rebooting by ssh-ing
into the router vms or a crash/start, is not know by the management server (Sheng's comment[1]).

Therefore, these bugs are resolved by design :
http://bugs.cloudstack.org/browse/CS-15907
http://bugs.cloudstack.org/browse/CS-15942

Request for comments to handle events outside of CS's scope for redundant routers: [2]

1. Async Callback:
 With bug http://bugs.cloudstack.org/browse/CS-15970 fixed, the management server knows when
router's redundant changed and CS re-applies iptables rules when state changes from UNKNOWN
(possible crash/reboot) to MASTER/BACKUP.

2. Pull mechanism:
 On reboot, a script/daemon on the router pulls any updates or iptables rules, but it won't
work if management server is down.

3, Push mechanism:
 CS periodically checks/resets/updates iptables rules etc. Cons: it's a bad design.

4. Modifying VRRP [3] [4] such that when one of the routers goes away, the other one will
be responsible to re-apply iptables rules. Cons: when both/all go down.

Best Regards,
Rohit

Refs:

[1] http://bugs.cloudstack.org/browse/CS-15907?focusedCommentId=139006&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-139006

[2] http://bugs.cloudstack.org/browse/CS-15907?focusedCommentId=138910&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-138910

[3] http://docs.cloudstack.org/CloudStack_Documentation/Design_Documents/Redundant_Virtual_Router

[4] http://tools.ietf.org/html/rfc3768
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