D&C GLug - Home Page

[ Date Index ] [ Thread Index ] [ <= Previous by date / thread ] [ Next by date / thread => ]

Re: [LUG] Dual-WAN routers?

 

I'm just looking for a backup system in case the main link goes down. I 
don't want to pay for 2 permanent connections, and mobile broadband will 
do, in an emergency.

I wondered if there was anything wrong with simply attaching it to your 
router / gateway machine and leaving it on all the time. You simply set 
the route metric to be higher than the ADSL connection. If the ADSL 
fails, surely the routing will fall back to the next highest metric, ie. 
the mobile broadband, and run over that until the ADSL comes back up?

For dual ADSL you are still dependent on a single technology. As you 
say, if a JCP digs up the cable, you lose both lines. With mobile you 
have an alternative route.

When EntaNet bothered providing a connection I had a static IP address, 
and from outside I could simply ssh tunnel into it. However, with mobile 
broadband they use their own NAT somewhere in their network. Does anyone 
know a solution to this? Skype works okay, so there is obviously a 
technique that punches through their and my NAT, but I don't know how to 
ssh in, short of setting up a reverse tunnel to an external machine. 
That would provide another point of failure, and slow the connection 
further.

Has anyone tried or solved this?

D

Gordon Henderson wrote:
> On Thu, 26 Feb 2009, Grant Sewell wrote:
>
>> I'm looking for a way have 2 direct ADSL connections on the same box
>> (be that a pre-fab router or a home-made router) where I can load
>> balance across them.
>>
>> Any ideas about the PCI ADSL cards?
>
> I've looked into this myself relatively recently as I've thought about 
> adding router capabilities to my PBX system - because that way I can 
> eliminate the rubbish offerings by most routers on the market these 
> days (bad or no traffic shaping, broken NAT handling and stupid SIP ALGs)
>
> I came to the conclusion that putting ADSL cards inside PCs was not 
> going to be the bet way because I couldn't find one that would work, 
> or be avalable. The next best thing was going to be USB adapters, but 
> I ruled that out for a PBX application (but not for my home gateway, 
> but I've not tried it yet).
>
> However what I've been seriously looking at is getting ADSL modems 
> (just a modem, not a router!), or turning existing modem/routers into 
> pure modems) that will work in half-bridge mode - effectively doing 
> protocol translation - PPPoA in, and PPPoE out.
>
> So you feed them into a Linux box with 1, 2, ... Ethernet ports and do 
> the PPPoE in the Linux box, the traffic shaping and load balancing there.
>
> Draytek make a reasonable modem for about 50 quid, but the going rate 
> appears to be from about £25 up to £100. I suspect they're more 
> expensive than a combined modem/router/wifi simply due to the lack of 
> volume sales.
>
> See:
>
>   http://www.broadbandbuyer.co.uk/default_ShopGroup.asp?ShopGroupID=1
>
> Just remember that load balancing, isn't bonding. You will not double 
> the speed on a single connection, but multiple users (or an 
> application opening multiple streams) will benefit. I'm sure you know 
> this, but will mention it as it's something I get asked from time to 
> time. You need compatable equipment at both ends of the link to do 
> channel bonding.
>
> And when that JCB comes along and digs up the road, it's going to take 
> all of them out :)
>
> For the actual load balancing stuff, there is a good starter on the 
> LARTC site - start here: http://lartc.org/
>
> It's been a while since I've set something like this up myself, but 
> looks like I might need to soon (with a 3G device as backup to main ADSL)
>
> Gordon


-- 
The Mailing List for the Devon & Cornwall LUG
http://mailman.dclug.org.uk/listinfo/list
FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html