[ale] failover planning

[Bob Toxen]

On Mon, Nov 29, 2004 at 07:49:43PM -0500, Christopher Fowler wrote:
> Speaking of failover is it possible to install 2 NICS in Linux and put
> them on the same subnet.  I.E. eth0 = 192.168.1.4 and eth1 = 192.168.1.5
> then place those NICS under load balancing.  In this case both will have
> the same DNS and same gateway.  All load balancing setups I've seen load
> balance between multiple Internet connections.
Sure.  No problem.  Of course, this is needed only if your total bandwidth
requirements exceed that of a single NIC (either 100 Mbps duplex or 1 Gbps).

Bob Toxen
bob at verysecurelinux.com               [Please use for email to me]
http://www.verysecurelinux.com        [Network&Linux/Unix security consulting]
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   -- Bob Toxen 10/03/2002


> On Mon, 2004-11-29 at 19:40, Greg Freemyer wrote:
> > On Mon, 29 Nov 2004 09:51:34 -0500, James P. Kinney III
> > <jkinney at localnetsolutions.com> wrote:
> > > I am looking at setting up a small non-local redundant webserver. The
> > > net access for each node is through different ISP's so each node has
> > > different IP's. In fact, there is nothing in common between the two
> > > different networks. They have no common router.
> > > 
> > > The main site is serverd by a T1 line that is susceptable to an outage
> > > caused by falling trees. I would like to make the outage as short as
> > > possible by making the backup site live as fast as possible. Right now,
> > > other than editing the DNS listing and waiting for the change to
> > > propogate, I have no other way to do this.
> > > 
> > > Any suggestions?
> > > --
> > > James P. Kinney III          \Changing the mobile computing world/
> > 
> > If nothing else, you could try round-robin DNS.
> > 
> > That way roughly half of your dns quiries will go to each IP.
> > 
> > Then set your client TTL low so your users are requesting a new DNS
> > entry fairly often.
> > 
> > If one of your sites fails,  there is a 50% chance your users will go
> > to the other site with their next DNS request.  (ie. if you have M$
> > users, they do a dns request at least once per reboot.)
> > 
> > Greg