WANPIPEŽ for Linux
There are several ways of doing this. One of the easiest and straight forward ways is 'TEQL' - "True" (or "trivial") link equalizer. Like most things having to do with queueing, load sharing goes both ways. Both ends of a link may need to participate for full effect.
However in real-world situations, users control only one side of the link, and telco the other.
What is needed
Make sure that TEQL modules has been compiled
modprobe -l | grep eql
The module name is "sch_teql".
If doesn't exist:
cd /usr/src/linux
make menuconfig
(network options-->QOS section--> enable TEQL as module)
make modules
make modules_install
Make sure that wanpipe has been installed and running.
Setup by Step Configuration
Start all wanpipe devices
wanrouter start
Load a TEQL kernel module
modprobe sch_teql
or
modprobe sch_teql max_equalizers=N
Where N=number of eql devices
Setup queueing disciplines on each wanpipe interface using iproute2 utility called 'tc'.
tc qdisc add dev wan0 root teql0
tc qdisc add dev wan1 root teql0
Interfaces wan0 and wan1 could be running any protocol WANPIPE supports (PPP, Frame Relay, CHDLC ...)
The device teql0 is basically a round-robbin distributor over wan0 and wan1, for sending packets. No data ever comes in over an teql device, that just appears on the 'raw' wan0 and wan1.
Set the ip address of teql interface. Note, theip address used is ARBITRARY, it is fake.
The reason for this is that packets will be forwarded through this ROUTER, thus packets will never originate from this box.
This means, however, that pinging from this machine will not be possible (your local address if fake).
ip addr add dev teql0 10.0.0.0/31
ip link set teql0 up
ip route del 10.0.0.0/31
ip route add default dev teql0
IMPORTANT: The default route must be on teql0 device.
Goth router A and B need to have return path filtering turned off, because they will otherwise drop packets destined for ip addresses other than their own:
echo "0" > /proc/sys/net/ipv4/conf/wan0/rp_filter
echo "0" > /proc/sys/net/ipv4/conf/wan1/rp_filter
Load Balancing Issues
There is the nasty problem of packet reordering. Let's say 6
packets need to be sent from A to B - wan0 might get 1, 3 and 5. wan1 would then do 2, 4 and 6. In an ideal world, router B would receive this in order, 1, 2, 3, 4, 5, 6. But the possibility is very real that the kernel gets it like this: 2, 1, 4, 3, 6, 5.
The problem is that this confuses TCP/IP. While not a problem for links carrying many different TCP/IP sessions, you won't be able to bundle multiple links and get to ftp a single file a lot faster, except when your receiving or sending OS is Linux :), which is not easily shaken by some simple reordering.
FAQ
Question
I cannot get a single connection incoming or (downloading from here) to download at greater that 175KB.
Answer
OK that sounds about right. The reason you are not getting download throughput of greater than 175KB is because your telco is not load balancing down to you. The telco is sending the download stream over a single link. However if you do multiple downloads you do see, a greater throughput.
In load balancing you can only control the outgoing direction. The incoming can only be controlled from the other end (telco end) of the link.
Question
My main concern is redundancy, it seems as if one line goes down the entire connection is dead. I assume this is because I cannot route the ips originally assigned to me on the first T1 over the new T1. Or am I mistaken. Should I be able to route say 216.133.91.193-222/27 over either line regardless of which are up or down?
Answer
The TEQL determines the state of the link via state of the network interface. Thus, if the link is down, the network interface must also come down and vice versa.
Wanpipe drivers have this option; to use the network interface state to show state of the link below.
Thus,enable the dynamic interface config (DYN_INTR_CFG) option in /usr/sbin/wancfg configurator. (or directly in wanpipe1.conf).
This option will bring the network interface down, if the line goes down !!! Once the interface goes down, it will be temporarily removed from the routing table until it comes back up.
Further questions or comments can be emailed to: Nenad Corbic |
