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+  EQL Driver: Serial IP Load Balancing HOWTO
+  Simon "Guru Aleph-Null" Janes, simon@ncm.com
+  v1.1, February 27, 1995
+
+  This is the manual for the EQL device driver. EQL is a software device
+  that lets you load-balance IP serial links (SLIP or uncompressed PPP)
+  to increase your bandwidth. It will not reduce your latency (i.e. ping
+  times) except in the case where you already have lots of traffic on
+  your link, in which it will help them out. This driver has been tested
+  with the 1.1.75 kernel, and is known to have patched cleanly with
+  1.1.86.  Some testing with 1.1.92 has been done with the v1.1 patch
+  which was only created to patch cleanly in the very latest kernel
+  source trees. (Yes, it worked fine.)
+
+  1.  Introduction
+
+  Which is worse? A huge fee for a 56K leased line or two phone lines?
+  It's probably the former.  If you find yourself craving more bandwidth,
+  and have a ISP that is flexible, it is now possible to bind modems
+  together to work as one point-to-point link to increase your
+  bandwidth.  All without having to have a special black box on either
+  side.
+
+
+  The eql driver has only been tested with the Livingston PortMaster-2e
+  terminal server. I do not know if other terminal servers support load-
+  balancing, but I do know that the PortMaster does it, and does it
+  almost as well as the eql driver seems to do it (-- Unfortunately, in
+  my testing so far, the Livingston PortMaster 2e's load-balancing is a
+  good 1 to 2 KB/s slower than the test machine working with a 28.8 Kbps
+  and 14.4 Kbps connection.  However, I am not sure that it really is
+  the PortMaster, or if it's Linux's TCP drivers. I'm told that Linux's
+  TCP implementation is pretty fast though.--)
+
+
+  I suggest to ISPs out there that it would probably be fair to charge
+  a load-balancing client 75% of the cost of the second line and 50% of
+  the cost of the third line etc...
+
+
+  Hey, we can all dream you know...
+
+
+  2.  Kernel Configuration
+
+  Here I describe the general steps of getting a kernel up and working
+  with the eql driver.  From patching, building, to installing.
+
+
+  2.1.  Patching The Kernel
+
+  If you do not have or cannot get a copy of the kernel with the eql
+  driver folded into it, get your copy of the driver from
+  ftp://slaughter.ncm.com/pub/Linux/LOAD_BALANCING/eql-1.1.tar.gz.
+  Unpack this archive someplace obvious like /usr/local/src/.  It will
+  create the following files:
+
+
+
+       ______________________________________________________________________
+       -rw-r--r-- guru/ncm      198 Jan 19 18:53 1995 eql-1.1/NO-WARRANTY
+       -rw-r--r-- guru/ncm      30620 Feb 27 21:40 1995 eql-1.1/eql-1.1.patch
+       -rwxr-xr-x guru/ncm      16111 Jan 12 22:29 1995 eql-1.1/eql_enslave
+       -rw-r--r-- guru/ncm      2195 Jan 10 21:48 1995 eql-1.1/eql_enslave.c
+       ______________________________________________________________________
+
+  Unpack a recent kernel (something after 1.1.92) someplace convenient
+  like say /usr/src/linux-1.1.92.eql. Use symbolic links to point
+  /usr/src/linux to this development directory.
+
+
+  Apply the patch by running the commands:
+
+
+       ______________________________________________________________________
+       cd /usr/src
+       patch </usr/local/src/eql-1.1/eql-1.1.patch
+       ______________________________________________________________________
+
+
+
+
+
+  2.2.  Building The Kernel
+
+  After patching the kernel, run make config and configure the kernel
+  for your hardware.
+
+
+  After configuration, make and install according to your habit.
+
+
+  3.  Network Configuration
+
+  So far, I have only used the eql device with the DSLIP SLIP connection
+  manager by Matt Dillon (-- "The man who sold his soul to code so much
+  so quickly."--) .  How you configure it for other "connection"
+  managers is up to you.  Most other connection managers that I've seen
+  don't do a very good job when it comes to handling more than one
+  connection.
+
+
+  3.1.  /etc/rc.d/rc.inet1
+
+  In rc.inet1, ifconfig the eql device to the IP address you usually use
+  for your machine, and the MTU you prefer for your SLIP lines. One
+  could argue that MTU should be roughly half the usual size for two
+  modems, one-third for three, one-fourth for four, etc...  But going
+  too far below 296 is probably overkill. Here is an example ifconfig
+  command that sets up the eql device:
+
+
+
+       ______________________________________________________________________
+       ifconfig eql 198.67.33.239 mtu 1006
+       ______________________________________________________________________
+
+
+
+
+
+  Once the eql device is up and running, add a static default route to
+  it in the routing table using the cool new route syntax that makes
+  life so much easier:
+
+
+
+       ______________________________________________________________________
+       route add default eql
+       ______________________________________________________________________
+
+
+  3.2.  Enslaving Devices By Hand
+
+  Enslaving devices by hand requires two utility programs: eql_enslave
+  and eql_emancipate (-- eql_emancipate hasn't been written because when
+  an enslaved device "dies", it is automatically taken out of the queue.
+  I haven't found a good reason to write it yet... other than for
+  completeness, but that isn't a good motivator is it?--)
+
+
+  The syntax for enslaving a device is "eql_enslave <master-name>
+  <slave-name> <estimated-bps>".  Here are some example enslavings:
+
+
+
+       ______________________________________________________________________
+       eql_enslave eql sl0 28800
+       eql_enslave eql ppp0 14400
+       eql_enslave eql sl1 57600
+       ______________________________________________________________________
+
+
+
+
+
+  When you want to free a device from its life of slavery, you can
+  either down the device with ifconfig (eql will automatically bury the
+  dead slave and remove it from its queue) or use eql_emancipate to free
+  it. (-- Or just ifconfig it down, and the eql driver will take it out
+  for you.--)
+
+
+
+       ______________________________________________________________________
+       eql_emancipate eql sl0
+       eql_emancipate eql ppp0
+       eql_emancipate eql sl1
+       ______________________________________________________________________
+
+
+
+
+
+  3.3.  DSLIP Configuration for the eql Device
+
+  The general idea is to bring up and keep up as many SLIP connections
+  as you need, automatically.
+
+
+  3.3.1.  /etc/slip/runslip.conf
+
+  Here is an example runslip.conf:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+  ______________________________________________________________________
+  name          sl-line-1
+  enabled
+  baud          38400
+  mtu           576
+  ducmd         -e /etc/slip/dialout/cua2-288.xp -t 9
+  command        eql_enslave eql $interface 28800
+  address        198.67.33.239
+  line          /dev/cua2
+
+  name          sl-line-2
+  enabled
+  baud          38400
+  mtu           576
+  ducmd         -e /etc/slip/dialout/cua3-288.xp -t 9
+  command        eql_enslave eql $interface 28800
+  address        198.67.33.239
+  line          /dev/cua3
+  ______________________________________________________________________
+
+
+
+
+
+  3.4.  Using PPP and the eql Device
+
+  I have not yet done any load-balancing testing for PPP devices, mainly
+  because I don't have a PPP-connection manager like SLIP has with
+  DSLIP. I did find a good tip from LinuxNET:Billy for PPP performance:
+  make sure you have asyncmap set to something so that control
+  characters are not escaped.
+
+
+  I tried to fix up a PPP script/system for redialing lost PPP
+  connections for use with the eql driver the weekend of Feb 25-26 '95
+  (Hereafter known as the 8-hour PPP Hate Festival).  Perhaps later this
+  year.
+
+
+  4.  About the Slave Scheduler Algorithm
+
+  The slave scheduler probably could be replaced with a dozen other
+  things and push traffic much faster.  The formula in the current set
+  up of the driver was tuned to handle slaves with wildly different
+  bits-per-second "priorities".
+
+
+  All testing I have done was with two 28.8 V.FC modems, one connecting
+  at 28800 bps or slower, and the other connecting at 14400 bps all the
+  time.
+
+
+  One version of the scheduler was able to push 5.3 K/s through the
+  28800 and 14400 connections, but when the priorities on the links were
+  very wide apart (57600 vs. 14400) the "faster" modem received all
+  traffic and the "slower" modem starved.
+
+
+  5.  Testers' Reports
+
+  Some people have experimented with the eql device with newer
+  kernels (than 1.1.75).  I have since updated the driver to patch
+  cleanly in newer kernels because of the removal of the old "slave-
+  balancing" driver config option.
+
+
+  o  icee from LinuxNET patched 1.1.86 without any rejects and was able
+     to boot the kernel and enslave a couple of ISDN PPP links.
+
+  5.1.  Randolph Bentson's Test Report
+
+
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+  From bentson@grieg.seaslug.org Wed Feb  8 19:08:09 1995
+  Date: Tue, 7 Feb 95 22:57 PST
+  From: Randolph Bentson <bentson@grieg.seaslug.org>
+  To: guru@ncm.com
+  Subject: EQL driver tests
+
+
+  I have been checking out your eql driver.  (Nice work, that!)
+  Although you may already done this performance testing, here
+  are some data I've discovered.
+
+  Randolph Bentson
+  bentson@grieg.seaslug.org
+
+  ---------------------------------------------------------
+
+
+  A pseudo-device driver, EQL, written by Simon Janes, can be used
+  to bundle multiple SLIP connections into what appears to be a
+  single connection.  This allows one to improve dial-up network
+  connectivity gradually, without having to buy expensive DSU/CSU
+  hardware and services.
+
+  I have done some testing of this software, with two goals in
+  mind: first, to ensure it actually works as described and
+  second, as a method of exercising my device driver.
+
+  The following performance measurements were derived from a set
+  of SLIP connections run between two Linux systems (1.1.84) using
+  a 486DX2/66 with a Cyclom-8Ys and a 486SLC/40 with a Cyclom-16Y.
+  (Ports 0,1,2,3 were used.  A later configuration will distribute
+  port selection across the different Cirrus chips on the boards.)
+  Once a link was established, I timed a binary ftp transfer of
+  289284 bytes of data. If there were no overhead (packet headers,
+  inter-character and inter-packet delays, etc.) the transfers
+  would take the following times:
+
+      bits/sec  seconds
+      345600    8.3
+      234600    12.3
+      172800    16.7
+      153600    18.8
+      76800     37.6
+      57600     50.2
+      38400     75.3
+      28800     100.4
+      19200     150.6
+      9600      301.3
+
+  A single line running at the lower speeds and with large packets
+  comes to within 2% of this.  Performance is limited for the higher
+  speeds (as predicted by the Cirrus databook) to an aggregate of
+  about 160 kbits/sec.  The next round of testing will distribute
+  the load across two or more Cirrus chips.
+
+  The good news is that one gets nearly the full advantage of the
+  second, third, and fourth line's bandwidth.  (The bad news is
+  that the connection establishment seemed fragile for the higher
+  speeds.  Once established, the connection seemed robust enough.)
+
+  #lines  speed mtu  seconds    theory  actual  %of
+         kbit/sec      duration speed   speed   max
+  3     115200  900     _       345600
+  3     115200  400     18.1    345600  159825  46
+  2     115200  900     _       230400
+  2     115200  600     18.1    230400  159825  69
+  2     115200  400     19.3    230400  149888  65
+  4     57600   900     _       234600
+  4     57600   600     _       234600
+  4     57600   400     _       234600
+  3     57600   600     20.9    172800  138413  80
+  3     57600   900     21.2    172800  136455  78
+  3     115200  600     21.7    345600  133311  38
+  3     57600   400     22.5    172800  128571  74
+  4     38400   900     25.2    153600  114795  74
+  4     38400   600     26.4    153600  109577  71
+  4     38400   400     27.3    153600  105965  68
+  2     57600   900     29.1    115200  99410.3 86
+  1     115200  900     30.7    115200  94229.3 81
+  2     57600   600     30.2    115200  95789.4 83
+  3     38400   900     30.3    115200  95473.3 82
+  3     38400   600     31.2    115200  92719.2 80
+  1     115200  600     31.3    115200  92423   80
+  2     57600   400     32.3    115200  89561.6 77
+  1     115200  400     32.8    115200  88196.3 76
+  3     38400   400     33.5    115200  86353.4 74
+  2     38400   900     43.7    76800   66197.7 86
+  2     38400   600     44      76800   65746.4 85
+  2     38400   400     47.2    76800   61289   79
+  4     19200   900     50.8    76800   56945.7 74
+  4     19200   400     53.2    76800   54376.7 70
+  4     19200   600     53.7    76800   53870.4 70
+  1     57600   900     54.6    57600   52982.4 91
+  1     57600   600     56.2    57600   51474   89
+  3     19200   900     60.5    57600   47815.5 83
+  1     57600   400     60.2    57600   48053.8 83
+  3     19200   600     62      57600   46658.7 81
+  3     19200   400     64.7    57600   44711.6 77
+  1     38400   900     79.4    38400   36433.8 94
+  1     38400   600     82.4    38400   35107.3 91
+  2     19200   900     84.4    38400   34275.4 89
+  1     38400   400     86.8    38400   33327.6 86
+  2     19200   600     87.6    38400   33023.3 85
+  2     19200   400     91.2    38400   31719.7 82
+  4     9600    900     94.7    38400   30547.4 79
+  4     9600    400     106     38400   27290.9 71
+  4     9600    600     110     38400   26298.5 68
+  3     9600    900     118     28800   24515.6 85
+  3     9600    600     120     28800   24107   83
+  3     9600    400     131     28800   22082.7 76
+  1     19200   900     155     19200   18663.5 97
+  1     19200   600     161     19200   17968   93
+  1     19200   400     170     19200   17016.7 88
+  2     9600    600     176     19200   16436.6 85
+  2     9600    900     180     19200   16071.3 83
+  2     9600    400     181     19200   15982.5 83
+  1     9600    900     305     9600    9484.72 98
+  1     9600    600     314     9600    9212.87 95
+  1     9600    400     332     9600    8713.37 90
+
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+
+  5.2.  Anthony Healy's Report
+
+
+
+
+
+
+
+  Date: Mon, 13 Feb 1995 16:17:29 +1100 (EST)
+  From: Antony Healey <ahealey@st.nepean.uws.edu.au>
+  To: Simon Janes <guru@ncm.com>
+  Subject: Re: Load Balancing
+
+  Hi Simon,
+          I've installed your patch and it works great. I have trialed
+          it over twin SL/IP lines, just over null modems, but I was
+          able to data at over 48Kb/s [ISDN link -Simon]. I managed a
+          transfer of up to 7.5 Kbyte/s on one go, but averaged around
+          6.4 Kbyte/s, which I think is pretty cool.  :)
+
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