On Fri, Dec 14, 2001 at 02:15:50PM -0200, Christoph Simon wrote: > On Fri, 14 Dec 2001 10:52:28 -0500 > Adrian Chung <adrian@xxxxxxxxxxxxxxxxxx> wrote: [...] > > My two links are through different ISP's, and I want to be able to use > > both ISP's news, and proxy servers. In order to do this, I need to > > make sure that when accessing ISP1's news server, I always connect via > > the same link. > > > > Load balancing defeats this, by sometimes routing to ISP1's news > > server via ISP2, and then I get denied access because I don't have a > > source IP on ISP1's network. > > You should be able to add an explicit host route in table main. That > is hit before the multipath route is queried. You do know the IP > of that ISP's news server, do you? Yes, although at one point I had noticed that almost everything for 24.0.0.0/8 was faster via the second link, but everything else was faster through the first link. So I was trying to avoid having to add individual host entries in the main table. But if I add the entire 24.0.0.0/8 network into the main table, if the second link goes down, I can't get to anything on that network at all. In any case, it works just fine adding a host route in the main table, and that's probably the best solution, since there aren't that many hosts that I connect to that require a certain source IP. This way as well, since ISP2's servers require an IP from their pool, if my second link goes down, there's no point in routing to that server from the first link, since their ACL's deny me access anyways. It's a good solution, just a little more legwork on my part enumerating all of the servers I need to talk to. Thanks! > > 1) is there a way to only use the second link if and when the first > > goes down, instead of load balancing via both links all the time? > > As I said above, the contrary was the aim of my setup. I would imagine > that the solution is not using a multipath route but just two default > routes with different priority. If the first is working, it should be > used always; if it goes down, the second would be used. And if the > first comes up again, thanks to Julian's patches, it should be used > again. But note, that for this last step to work, I think you still > need to ping/arping the gateways, such that there is a chance to > detect that the failing link is up again. What do you mean by "two default routes with different priority"? Do you mean different 'ip rule prio' priorities? Or something else? That sounds like it would be viable, I'm just not sure how I do that. :) > > Does any of this make sense? > > Unless you have to pay for traffic on one link and not on the other, > I'm not sure why you would want to leave a link unused. Beside that, I > think it does make sense. Actually, I'd rather not leave it unused, but before these patches, I couldn't get multipath routing/load balancing to work at all. :) Now, I don't mind load balancing across both, as long as specific ISP servers which need to see a certain source IP get reached via the right link, but from above, I now can do that. -- Adrian Chung (adrian at enfusion-group dot com) http://www.enfusion-group.com/~adrian GPG Fingerprint: C620 C8EA 86BA 79CC 384C E7BE A10C 353B 919D 1A17 [rogue.enfusion-group.com] up 134 days, 3:57, 3 users
