I've been reading that it's possible to set up a system with multiple NIC to provide redundant internet connectivity such that it will switch to a secondary connection if the primary ISP fails. Is it possible in a similar way to setup redundant LAN routing? I read that it is possible to aggregate/bond multiple NIC to stackable switches that support link aggregation and redundancy. But if only simple switches are available, is something like this possible? e.g. System A eth0 -> lan switch/router 1 eth1 -> lan switch/router 2 System B eth0 -> lan switch 1 eth1 -> lan switch 2 Then somehow specify that, if lan switch 1 fails, the two systems will switch to using switch 2 so that in case of a switch failure, the network continues to remain operational.
On Sat, Jul 10, 2010 at 5:21 PM, Emmanuel Noobadmin <centos.admin at gmail.com> wrote:> > I've been reading that it's possible to set up a system with multiple > NIC to provide redundant internet connectivity such that it will > switch to a secondary connection if the primary ISP fails. > > Is it possible in a similar way to setup redundant LAN routing? I read > that it is possible to aggregate/bond multiple NIC to stackable > switches that support link aggregation and redundancy. But if only > simple switches are available, is something like this possible? > > e.g. > System A > eth0 -> lan switch/router 1 > eth1 -> lan switch/router 2 > > System B > eth0 -> lan switch 1 > eth1 -> lan switch 2 > > Then somehow specify that, if lan switch 1 fails, the two systems will > switch to using switch 2 so that in case of a switch failure, the > network continues to remain operational. > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centosI'd think for this to be possible you will need a router with multiple WAN addresses/interfaces... I am not sure how that pertains to your LAN per se. Boris.
On Sun, Jul 11, 2010 at 05:21:50AM +0800, Emmanuel Noobadmin wrote:> e.g. > System A > eth0 -> lan switch/router 1 > eth1 -> lan switch/router 2 > > System B > eth0 -> lan switch 1 > eth1 -> lan switch 2 > > Then somehow specify that, if lan switch 1 fails, the two systems will > switch to using switch 2 so that in case of a switch failure, the > network continues to remain operational.If you're clever with scripting and iproute2 commands, rules and multiple routing tables, and everything's Linux, this is certainly doable. You could have your System A ping System B's IP via eth0 every minute, and on failure reassign its default route and IP to eth1. Meanwhile you can set up rules and routes on System B so that whichever NIC traffic comes in on, the response will use the same NIC ... stuff you'll find if you google around for how to be dual-homed between ISPs is quite applicable here. It's too complex to work it out for you in detail without spending an hour on it. But I've done this sort of thing and had it work very well. Whit
Greetings, On 7/11/10, Emmanuel Noobadmin <centos.admin at gmail.com> wrote:> I've been reading that it's possible to set up a system with multiple > NIC to provide redundant internet connectivity such that it will > switch to a secondary connection if the primary ISP fails. > > Is it possible in a similar way to setup redundant LAN routing? I read > that it is possible to aggregate/bond multiple NIC to stackable > switches that support link aggregation and redundancy. But if only > simple switches are available, is something like this possible? > > e.g. > System A > eth0 -> lan switch/router 1 > eth1 -> lan switch/router 2 > > System B > eth0 -> lan switch 1 > eth1 -> lan switch 2 > > Then somehow specify that, if lan switch 1 fails, the two systems will > switch to using switch 2 so that in case of a switch failure, the > network continues to remain operational.hmm.. lartc.org comes to mind to begin with... duh.. that was too primitive. pfSense perhaps... But then there is untangle if you want to pay them.. etc. etc. Regards, Rajagopal
On 7/10/2010 2:21 PM, Emmanuel Noobadmin wrote:> I've been reading that it's possible to set up a system with multiple > NIC to provide redundant internet connectivity such that it will > switch to a secondary connection if the primary ISP fails. > > Is it possible in a similar way to setup redundant LAN routing? I read > that it is possible to aggregate/bond multiple NIC to stackable > switches that support link aggregation and redundancy. But if only > simple switches are available, is something like this possible? > > e.g. > System A > eth0 -> lan switch/router 1 > eth1 -> lan switch/router 2 > > System B > eth0 -> lan switch 1 > eth1 -> lan switch 2 > > Then somehow specify that, if lan switch 1 fails, the two systems will > switch to using switch 2 so that in case of a switch failure, the > network continues to remain operational.Yes. You can do it. I've done it before. All you need is the right choice of bonding mode . You set up bond0 for eth0 and eth1 and it 'just works'. To make it more robust, cross-connect the two switches as well. -- Benjamin Franz