On Nov 24, 2013, at 10:36 PM, Eugeniu Patrascu <[email protected]> wrote:
> On Fri, Oct 11, 2013 at 8:27 PM, William Waites > <[email protected]>wrote: > >> I'm having a discussion with a small network in a part of the world >> where bandwidth is scarce and multiple DSL lines are often used for >> upstream links. The topic is policy-based routing, which is being >> described as "load balancing" where end-user traffic is assigned to a >> line according to source address. >> >> In my opinion the main problems with this are: >> >> - It's brittle, when a line fails, traffic doesn't re-route >> > > You can always know what IPs are on the other end of the link, add static > routes for them to make sure they're reachable and based on ping results > use the link or not. It works fairly well if 1-2 minutes of downtime is not > an issue. I've done this using Linux and a bash script and it worked to > balance traffic across two links with up/down detection. iproute2 does > wonders. > Or you could run FreeBSD with PF and ifstated and it would be an almost instantaneous failover. > >> - None of the usual debugging tools work properly >> > > As long as you don't have asymmetric routing in place, debugging will be > the same. Even so, you can (at least on Linux) do a "tcpdump -i any" and > see what goes in/out of your box :) > > Asymmetric routing is a fact of life and is fairly common. >> - Adding a new user is complicated because it has to be done in (at >> least) two places >> >> > I agree it's not scaleable, but for when all you have are DSL lines or low > capacity lines over which you cannot run an IGP, you'll have make it work > with what you have :) > > >> But I'm having a distinct lack of success locating rants and diatribes >> or even well-reasoned articles supporting this opinion. >> >> > I would go for the "right tools for the right job" idea and say that PBR in > the case you're mentioning of a valid use and probably the most effective > way of doing business for them. > > Also take into consideration that in many parts of the world, the effort of > configuring and maintaining a setup like this fall in the the day to day > job of one or several network admins. Also, most of the time is cheaper to > hire more people than go and buy let's say professional networking > equipment. Hmm, really? The professional networking equipment required for this type of thing would be in the ~10k new and significantly cheaper used. That's not a lot of salary. Mike
