Multiple Internet connection with failover/load-balancing

[Nick Rogness]

On Thu, 20 Mar 2003, Domain Administrator wrote:

> Hello all,
>
> We've been offering commercial Internet failover/load-balancing products
> to our clients, but we occasionally receive requests by some clients to
> provide less costly solution.  While full redundancy for both inbound
> and outbound traffic will require BGP or OSPF, these clients simply wish
> to join multiple Internet connections (DSL, ISDN or T1) from different
> providers to gain failover capability should one of their links failed.
> Without ISPs' support, this type of redundancy only applies to outbound
> traffic, but that will suffice the clients' requirements already.
>
> I searched through the mailing lists and forums but found only very
> limited resources on how to accomplish such gateway/firewall setup using
> FreeBSD (or other BSD).  It seeems for this type of setup requires
> running of multiple NAT daemons.  Has anyone done something like this?
> or point me to any HOW-TOs?
>

	Load balancing "may" be done using some tricks with ipfw and natd,
	but for most practical and straight forward approaches it should
	be left up to route peering with ISPs.

	Without tremendous work, failover is very difficult to do with
	the basic routing tools supplied with BSD.  You can do failover
	with different tools but be mindfull of routing as you may route
	IPs provided by ISP-A through your ISP-B connection.  Search the
	archives for suggestions on how to do failover.

	Proper care and consideration needs to be made before failover can
	work.  Nothing pisses off ISPs more than some jackass with
	misconfigured routing causing unnecessary traffic on their
	network.  This would not be a problem if you only get one IP from
	your ISPs.

	So yes, failover can be accomplished with lots of work and for all
	practical purposes (no route peering) load balancing can not.
	(I'm making a blanket statement here because load balancing "may"
	be accomplished with some thought and use of ipfw/nat
	interworkings).

	My plain and simple answer is to buy a basic router and
	route peer to avoid the headache.  You get failover and load
	balancing at the same time.

Nick Rogness <nick at rogness.net>
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