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4 Replies Latest reply: May 31, 2011 6:37 PM by alan.pae RSS

Default route selection

user254909 Newbie
Currently Being Moderated
We are using two same applications running on two different Solaris machines. By default, there are two default routes present on each of Solaris box on which application runs.

What we are observing here is that on one of the machine Solaris uses first signaling interface (corresponding to 1st default route) for approx. 30 mins to send out a packet and then it switches to 2nd signaling interface (corresponding to 2nd default route) and then uses it for next 20-30 mins.

On the other machine, Solaris uses first signaling interface (corresponding to 1st default route) for approx. 5 secs to send out a packet and then it switches to 2nd signaling interface (corresponding to 2nd default route) and then uses it for next few seconds.

So, we would like to know that what makes Solaris to switch between default routes. Our application in this case is using “res_nmkquery ” system call and only provides destination address to this API.Is there is any standard algorithm being used by Solaris to select a route among the multiple default routes ?

Thanks!
  • 1. Re: Default route selection
    alan.pae Journeyer
    Currently Being Moderated
    By default Solaris uses RIP. RIP uses a round robin algorithm to determine the default route if more than one is present. There has been a ton of questions about forcing it to use one or the other and you can setup a filter using ipf to accomplish that but Solaris has no mechanism to do what is called "Source Routing." Which is where the host determines the route to take to the endpoint.

    Web Search Routing Information Protocol for more details.

    alan
  • 2. Re: Default route selection
    805188 Newbie
    Currently Being Moderated
    alan.pae wrote:
    By default Solaris uses RIP. RIP uses a round robin algorithm to determine the default route if more than one is present. There has been a ton of questions about forcing it to use one or the other and you can setup a filter using ipf to accomplish that but Solaris has no mechanism to do what is called "Source Routing." Which is where the host determines the route to take to the endpoint.

    Web Search Routing Information Protocol for more details.

    alan
    Actually it is not RIP that does the round-robin, it is the kernel itself

    But more pertinent to the original poster's question, while we don't support Source Routing,
    we do have support for the strong and src-priority hostmodel in Solaris 11. Strong hostmodel
    will only send (locally originated) packets out to a default router on an interface that is on
    the same subnet as the source address of the packet. The "src-preferred" hostmodel will
    first try to the strong hostmodel behavior, and if no matching route can be found, will fall
    back to the weak (default) hostmodel behavior.

    Let me know if you need additional clarifications.

    --Sowmini                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
  • 3. Re: Default route selection
    alan.pae Journeyer
    Currently Being Moderated
    But more pertinent to the original poster's question, while we don't support Source Routing,
    we do have support for the strong and src-priority hostmodel in Solaris 11. Strong hostmodel
    will only send (locally originated) packets out to a default router on an interface that is on
    the same subnet as the source address of the packet. The "src-preferred" hostmodel will
    first try to the strong hostmodel behavior, and if no matching route can be found, will fall
    back to the weak (default) hostmodel behavior.
    Is this documented anywhere? As in, it might turn into a blog post.

    thanks,
    alan
  • 4. Re: Default route selection
    alan.pae Journeyer
    Currently Being Moderated
    It's part of ipadm.

    man ipadm on a Solaris 11 Express box.

    also

    http://download.oracle.com/docs/cd/E19963-01/html/821-1458/ggtvn.html

    alan

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