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Dirty Load Balancing

Posted <2016-12-22 Thu 16:14> by Aaron S. Jackson.

I am currently staying at my parents' house over Christmas. They are in the middle of nowhere and have very poor internet connection. They recently had a new ADSL line installed, provided by Andrews & Arnold. While the previous line still has ADSL, they kept it just for telephone service.

This afternoon I spent a bit of time trying to load balance the two connections with a half dead DrayTek router. Unfortunately the ADSL/VDSL port has been burnt out by a strike of lightning. It only supports 3G/4G modems via USB, and there is only one WAN ethernet port.

Due to these restrictions, my only option is to load balance using static routes, to routers on the same subnet. So, there are now three routers.

192.168.10.145   tplink        aaisp dsl
192.168.10.146   speedtouch    xilo dsl
192.168.10.254   draytek       defalt route

The DrayTek is the default route for the subnet and also dishes out the IP addresses. It has the following routing table:

Key: C - connected, S - static, R - RIP, * - default, ~ - private
S~           0.0.0.0/ 128.0.0.0        via 192.168.10.145    LAN
S~         128.0.0.0/ 128.0.0.0        via 192.168.10.146    LAN
C~      192.168.10.0/ 255.255.255.0    directly connected    LAN

Basically the internet has been divided in half, split between two connections. The main problem with this is that if one of the connections goes down, half the internet will not be accessible. From what I can tell, the DrayTek does not allow you to define static route priorities or fallover routes. Quick example...

$ traceroute google.com
traceroute to google.com (64.233.167.102), 30 hops max, 60 byte packets
 1  my.router (192.168.10.254)  3.275 ms  3.726 ms  3.704 ms
 2  192.168.10.145 (192.168.10.145)  3.271 ms  5.694 ms  6.287 ms
^C
$ traceroute speedtest.net
traceroute to speedtest.net (151.101.128.230), 30 hops max, 60 byte packets
 1  my.router (192.168.10.254)  3.307 ms  3.772 ms  3.752 ms
 2  192.168.10.146 (192.168.10.146)  49.445 ms  48.618 ms  48.193 ms
^C

It'll do for now. I will look into a better solution for the load balancing.

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Tags: networking hacks

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Copyright 2007-2017 Aaron S. Jackson (modified: Sun 23 Jul 14:30:46 BST 2017)