Multi-Homing Your Home Network?

Jens asks: "For some time now, I have been looking for an affordable solution to multi-home my little network. I have both DSL and cable feeds and it would be nice to combine them with some basic load sharing but more importantly with some failure protection for both incoming and outgoing traffic. My DNS provider allows for round robin access to my two feeds for incoming traffic load sharing and to dynamically change my DNS entry which could be used for feed failure protection. Are there any Slashdot readers who have tackled this problem? Seems like there are quite a few people out there in my shoes but nobody seems to have found the magic solution."

It's not easy.

[little_fluffy_clouds]

I'm still looking for the 'magic solution' myself - trouble is, it is rather complicated to get this right. It sure is fun though! Some links I have found handy in the past, probably more for those people who don't know all that much about it:

Multihoming and BGP FAQ [connect.com.au] - has some links to the RFC's etc.

Avi Freedman's site [freedman.net] has some very useful docs, in particular his Multihoming for the small ISP [netaxs.com], and his newer BGP Routing docs [netaxs.com]. He even has a powerpoint presentation titled "How to Multi Home" [freedman.net] but I have not seen it.

Can be done, could be better

[haplo21112]

Well if you play with your local routing table a little you can certainly set things up so "certain
" traffic goes in and out one source, and "other" traffic through the other. How could it be better, if Cable and DSL compnaies would treat our connections as "real" connections, with full routing and so forth.

Re:Can be done, could be better

[aonaran]

I'm not sure what you mean by "full routing", but if you want to be able to do BGP style multi-homing forget about it.

In order to do BGP you need your own ARIN assigned IP numbers (not ones issued by the ISP) To get a block of numbers from ARIN you have to already have 16 /24 blocks from your ISP (that's 16 Class C networks in oldfashioned terms)

I'd love to be able to use BGP for my small Cable system (serves 2 rural towns, a total of 800 odd customers) but we aren't big enough. Your home network most certainly is not big enough.

Multi-homed network

[ka9dgx]

At work, we have twin DSL feeds, one wireless based (through Teligent) and one a conventional DSL. Both ISPs give us a 64 address IP block. I put dual NICs in all the servers, and set up dual hubs, etc. I did this more to make it easier to troubleshoot for myself than for any other reason. We host all of our own services, including DNS through this, and it works well.

The workstations all hang off of the "primary" (faster) DSL line, all servers see both. In the event of failure of the "primary", I'll simply change our DHCP server to point to the secondary, move the workstation hubs to the other side of the servers, and we're back in business.

You CAN put both sets of IP addresses through the same network hardware, but unfortunately, Windows 95, and 98 don't do multiple IPs on a single NIC. Our servers are smarter than that.

Hope this helps.

--Mike--

Re:Multi-homed network

[Snowfox]

You CAN put both sets of IP addresses through the same network hardware, but unfortunately, Windows 95, and 98 don't do multiple IPs on a single NIC. Our servers are smarter than that.

Sure they do:
http://support.microsoft.com/support/k b/articles/Q156/7/72.ASP [microsoft.com]

Forget multihoming. Load balancing, but no BGP

[BigJim.fr]

Stop dreaming, no consumer ISP is going to let you send BGP annoucements into their network. Can't blame them though : BGP in novice hands is a very convenient way to fuck up spectacularily.

Go for proxy-based load balancing for the HTTP traffic, go for TEQL (loadsharing over multiple interfaces [linuxdoc.org] queuing in order to split the rest, use RIP to announce availability of outbound connections. Basically, you can do almost anything you want with outgoing connections, but you're pretty much stuck if you want inbound failover.

Give me a consumer DSL access provider that does BGP and I'll be a happy man ! Right now, no one gets it unless getting access through large-ish leased lines with lavish support and matching price tag.

Re:Forget multihoming. Load balancing, but no BGP

[LWolenczak]

Forget DSL, get a cheap T1 from an ILEC, they will let you run BGP.

Re:Forget multihoming. Load balancing, but no BGP

[BigJim.fr]

> Forget DSL, get a cheap T1 from an ILEC, > they will let you run BGP.

Unfortunately I live in France. You would be surprised how expensive T1 and their equivalents are on our side of the pond. I'm not complaining though : at least wine is not a luxury item and stinking cheese is not illegal here.

You are not alone

[Archfeld]

I live in Calif and I can get an 768 SDSL line for 150 a month. A T1 runs about 700$ + local loop chrges which PAC-BELL wants around 300 a month. I wish I lived in an area with some competition but PAC-BELL owns the whole ball of wax down here :(

Re:Forget multihoming. Load balancing, but no BGP

[BigJim.fr]

> Forget DSL, get a cheap T1 from an ILEC, > they will let you run BGP.

Actually, the whole point of multihoming on consumer DSL/cable access is to pool neighborhood accesses to the Internet. Considering the profile of consumer taffic, the whole neighborhood would benefit from the aggregate capacity. Add a bit of community wireless lan... Maybe I should stop daydreaming...

Ummmm define cheap.

[RomulusNR]

DSL runs $40/mo, bargain basement T1 runs $400/mo (& that's being really optimistic).

Re:Ummmm define cheap.

[LWolenczak]

Cheap as in you partner with the ILEC to do installs, and then cut a deal with them so you only have to pay the loop charge.

What I mean as DSL, is SDSL, and in most cases, that will run you atleast 230-400 a month anyway. Most local loop charges are from 400-700, but I have been on the phone with AT&T getting quotes for customers, and I got a tech to curse once when he saw what the loop charge was for one of my customer's locations ($1300 a month)

ip masq?

[cloudmaster]

You've got round-robin for the outside coming in, that's about as good as you'll probably get without some specialized hardware. For the outbound traffic, you could use iptables' round-robin masquerading. Set up your gateway so that all outbound traffic goes into it. Then set up a rule to masquerade a range of IPs - 2 IPs, in this case. So all of your outgoing traffic appears to have one of 2 source addresses.

This is where I get kinda fuzzy on the setup. You have to figure out a way to send traffic with source address 1 out the cable side while traffic with source address 2 goes out the DSL side. I'm not sure exactly how to do so, but at least that gets you to the point where you just have to filter on one of two source addresses...

Alternatively, what happens when you add 2 default gateways to your routing table? Can you just stick one machine on each cable/dsl connect, and have your network gateway use those 2 machines as its default gateways? That'd be cool if it worked... :)

Re:ip masq?

[LWolenczak]

Well, The first entered has priority, the second entered is a failover. I'm doing this with my wireless and wired network connections. If my ethernet cable gets unplugged, after about 10 seconds, linux figures out oh, that link is down, so it uses the wireless card as the default interface.

Re:ip masq?

[cloudmaster]

Oh. Well, that's a sensible way for it to behave in most situations, though I guess that's less than helpful in the poster's. Bringing the interface up and down every 20 seconds wouldn't be terribly efficient load-balancing... :)

Thanks. It sure is rare that I learn something useful from Slashdot...

Re:ip masq?

[LWolenczak]

Yeah, it would be ineffecent.... I kind of find it annoying that it takes soo long for linux to figure out whats up, so I'm just figuring it would be better to just manually shutdown the wired interface.

when we were loosing bluestar, we managed to get a T1 pulled, and we had both up and running for about 12 hours w/o problems.... though we had all the packets leaving on one line...

Forget it

[ikekrull]

You can't have inbound failover, the political structure of the those in control of the internet have deemed that you, as a small player, should not have the ability to do this.

Theoretically, you could obtain a /18 or /19 block of routable IPs from InterNIC (or whatever they are called these days, or in your part of the world), and arrange to BGP peer with several local ISPs, which would give you exactly what you want.

However, if you think you will actually be able to successfully do this, without licking ass, emptying your wallet and generally getting fucked around by all and sundry, forget it.

The 'routable' internet is pretty much closed to new players, might as well get used to being 'just another host'

Some info

[Stinking Pig]

I've put up some tips and things to look for here. [monkeynoodle.org] In short, you might be better off setting up two routers. TEQL might help with 1 router, haven't gotten it going yet. HTH,

Re:Some info

[Stinking Pig]

Is it just me, or is Slashdot really annoying to use with all the lameness filters and slow-down-cowboy filters and such?? I mean, I still read it for news, but posting is a pain and so I rarely do. Tonight is no exception.

So, I screwed up the URL above -- it should be http://www.monkeynoodle.org/lrp/LRP-Load-Balancing -HOWTO.html [monkeynoodle.org].

Sheesh.