4 Replies Latest reply: May 31, 2011 8:37 PM by alan.pae RSS

    Default route selection

    jain
      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
          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
            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
              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
                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