ADSL Bandwidth Management HOWTO

§@ªÌ:Dan Singletary dvsing@sonicspike.net
ĶªÌ:³¯±Ó¼C expns@yahoo.com
     _________________________________________________________________

   ³o¥÷¤åÀÉ´y­z¦p¦ó±N Linux ³]©w¦¨¾Ö¦³±a¼eºÞ²z¥\¯àªº¸ô¥Ñ¾¹,¦³®Ä¦aºÞ²zADSL
   ©M¨ä¥¦bandwidth ³]³Æ(cable modem, ISDN, µ¥µ¥) 
     _________________________________________________________________

1. ¤¶²Ð

     * 1.1 ¤åÀɪº³Ì·sª©¥»
     * 1.2 ¶l¥ó¦Cªí
     * 1.3 Án©ú
     * 1.4 ´¼¼z°]²£Åv©M³\¥i
     * 1.5 ¤ÏõX»P­×¥¿

2. ­I´º

     * 2.1 ¥²­n±ø¥ó
     * 2.2 §G§½
     * 2.3 Packet Queues(¼Æ¾Ú¥]¶¤¦C)

3. ¤u§@­ì²z

     * 3.1 Throttling Outbound Traffic with Linux HTB(¨Ï¥ÎHTB±±¨î¥X¯¸³q
       °T)
     * 3.2 Priority Queuing with HTB(¨Ï¥Î HTB ³]©w¶¤¦CÀu¥ýÅv)
     * 3.3 ¨Ï¥Îiptables ¹º¤À¥X¯¸ªº³q°T
     * 3.4 ÁÙ¥i¥H¦A«õ±¸¤@¤U
     * 3.5 Attempting to Throttle Inbound Traffic(±±¨î¤J¯¸ªº³q°T)
     * 3.6 ¬°¤°»ò¤J¯¸ªº³q°T­­¨î¬Ý°_¨Ó¤£«ç»ò¼Ë

4. °õ¦æ

     * 4.1 Caveats
     * 4.2 Script: myshaper

5. ´ú¸Õ

6. OK It Works!! Now What?
     _________________________________________________________________

1. ¤¶²Ð

   ¤åÀɪº¥Ø¦a¬O´£¨Ñ¤@­Ó¥i¦æªº¤èªkºÞ²zADSL(cable mode)¥X¯¸ªº³q«H.

1.1 ¤åÀɪº³Ì·sª©¥»

   ±z¥i¥H¦b [1]http://www.tldp.org §ä¨ì³o¥÷¤åÀɪº³Ì·sª©¥».

1.2 ¶l¥ó¦Cªí

   ¦³ÃöADSL Bandwidth Manage ªº°ÝÃD©M«H®§½Ð­q¾\: [2]jared.sonicspike.net

1.3 Án©ú

   ¦pªG±Ä¥Î¤F³o¥÷HOWTO·í¤¤ªº¤èªk¦Ó¹ï³]³Æ©Î³y¦¨¥ô¦ó¹k¥¢,µL½×¬O§@ªÌ, ´²§GªÌ
   ©Î¹ï³o¥÷HOWTO¦³°^Ämªº¤H³£±N©Úµ´©Ó¾á¥ô¦ó³d¥ô.

1.4 ´¼¼z°]²£Åv©M³\¥i

   ¦¹HOWTOªº´¼¼z°]²£Åv¬°Dan Singletary©Ò¦³:

   This document is copyright 2002 by Dan Singletary, and is released
   under the terms of the GNU Free Documentation License, which is hereby
   incorporated by reference.

1.5 ¤ÏõX»P­×¥¿

   ¦pªG±z¹ïHOWTO¦³¤°»ò°ÝÃD©Î¬Ýªk,½Ð¦b¦³ªÅªº®É­Ôµ¹§@ªÌ
   ¨Óe-mail:dvsing@sonicspike.net

2. ­I´º

2.1 ¥²­n±ø¥ó

   ­nÂI: ³o¨Ç¤èªk¾¨ºÞ¨S¦³¦b¨ä¥¦ªºµo¦æª©¤¤¸ÕÅç¹L,§Ú·Q¥¦¥¿±`¤u§@¤j·§¨S¤°»ò
   °ÝÃD.¤U­±¬O¹B¦æªºÀô¹Ò:
     * Red Hat Linux 7.3
     * 2.4.18-5 §¹¥þ¤ä«ù QoS ªº®Ö¤ßª©¥» (¼Ò²Õ¤]¥i¥H) ¥]§t¥H¤Uªºpatches (
       ¸É¤B)(¥i¯à·|³Ì²×¥[¤J¨ì³Ì·sªº®Ö¤ß·í¤¤):
     * HTB queue - [3]http://luxik.cdi.cz/~devik/qos/htb/ ª`·N: Mandrake(
       °Ò¼wµÜ§J8.1, 8.2)ªº®Ö¤ß¦Û 2.4.18-3 °_´N¦³¤FHTB ªº patches.
     * IMQ device - [4]IMQ device - http://luxik.cdi.cz/~patrick/imq/
     * iptables ª©¥»v1.2.6a ©Î§ó·sªº(version of iptables distributed with
       Red Hat 7.3 is missing the length module)

   Note: Previous versions of this document specified a method of
   bandwidth control that involved patching the existing sch_prio queue.
   It was found later that this patch was entirely unnecessary.
   Regardless, the newer methods outlined in this document will give you
   better results (although at the writing of this document 2 kernel
   patches are now necessary. :) Happy patching.)

2.2 §G§½

   ¤ÆÁc¬°Â²,©Ò¦³ªº³]©w¨Ì·Ó¤U­±³o­Ó§G§½¶i¦æ:
       ______________________________________________________________

  <-- 128kbit/s      --------------     <-- 10Mbit -->
  Internet <--------------------> | ADSL Modem | <--------------------
                1.5Mbit/s -->     --------------                     |
                                                                     | eth0
                                                                     V
                                                         -----------------
                                                         |               |
                                                         | Linux Router  |
                                                         |               |
                                                         -----------------
                                                          | .. | eth1..ethN
                                                          |    |
                                                          V    V

                                                       Local Network
       ______________________________________________________________

2.3 Packet Queues(¼Æ¾Ú¥]¶¤¦C)

   Packet Queues¬O¤@­Ó®e¾¹, ·í¼Æ¾Ú¤£¯à³Qºôµ¸³]³Æ¥ß¬J°e¨«ªº®É­Ô, Packet
   Queues ­t³d¼È®É¦¬¯d¥¦­Ì. °£«D³Q³]©w¦¨¥t¥~¤@ºØ¤è¦¡,§_«h¼Æ¾Ú¥]¬O«ö FIFO
   (first in, first out ³Ì¦­¶i¤JQueuesªº¼Æ¾Ú±N³Q³Ì§Öµo°e¨«) ¶i¦æ±Æ¶¤.

  The Upstream(¦V¤W¶Ç¿é)

   ADSLªº±a¼e¥Ñ¤£¹ïºÙªº 1.5Mbit/s downstream(¦V¤U¶Ç¿é)©M128kbit/sec
   upstream(¦V¤W¶Ç¿é)²Õ¦¨. Linux ¸ô¥Ñ¾¹(¥D¾÷)¦PADSL modemªº³sµ²³t²v
   ¦b10Mbits/s¥ª¥k.¦pªG Linux ¸ô¥Ñ¾¹¦P Local Network(¥»¦aºôµ¸) ªº³sµ²³t²v
   ¤]¦b10Mbits/s¥ª¥k,¸ô¥Ñ¾¹©MLocal Network(¥»¦aºôµ¸)ªºQueues(¶¤¦C)´N¤£·|
   ¦s¦b.¦ý¥H10Mbits/s¨ì¹FADSL modemªº¼Æ¾Ú¥]«o­n¥H128kbit/sec ¶Ç¿é
   ¨ìInternet.¦]¦¹¼Æ¾Ú¥]±N¦bADSL modem§Î¦¨Queues,ADSL modem±N¤£¯àÀ³¥I¦Ó²£
   ¥Í¼Æ¾Ú¥]¥á¥¢²{¶H. TCP´N¬O¥Î¨Ó±±¨îÃþ¦ü³o¼Ëªº±¡ªp,¥¦½Õ¾ã¶Ç¿éµ¡¤fªº¤j¤p¥H
   ¹F¨ì§Q¥Î±a¼eªº³Ì¨Î®ÄªG.

   TCP±±¨îQueues(¶¤¦C)¥H§Q¥Î±a¼e. ¸û¤jªºFIFO Queues±N©µªø¼Æ¾Ú¥]ªº¶Ç°e®É
   ¶¡.

   ¥t¤@ºØ¦PFIFO¦³ÂI¬Û¦üªºQueues(¶¤¦C)¬O n-band priority queue, ¥¦¨ú¥NFIFO
   ¥u¦³¤@­Ó¶¤¦Cªº°µªk, ¼Æ¾Ú¥]¤À¯Å§O±Æ¥X¦h­ÓFIFO Queues(¶¤¦C), ¨C¤@
   ­ÓQueues³£¦³Àu¥ý¯Å§Oªº³]©w, Á`¬O±q¯Å§O°ªªºQueues±N¼Æ¾Údequeued(¥X¦C).
   ¨Ï¥Î³oºØ¤èªk,FTP©Mtelnet¦P®É¤W¸ü¼Æ¾Ú¥]ªº®É­Ô, telnetªº¼Æ¾Ú¥]±N±o¨ì§ó°ª
   ªºÀu¥ý¯Å§O.³æ¿Wªºtelnet¼Æ¾Ú¥]±N³Q¥ß¬Jµo°e.

   Linux ¨Ï¥Î¤@ºØ·sªºQueues: Hierarchical Token Bucket (HTB Ķ¬°¤À¯Å«¬¦¡
   ªº¶¤¦C®e¾¹). ¥¦¦³ÂI¹³n-band priority queue, ¦ýn-band priority queue¦b
   ¨C­Ó¯Å§O¤¤¥u¦³­­¨î¼Æ¾Ú³q°Tªº¯à¤O. HTB¦³¤@¶µ§ó¥[¥ý¶iªº¥\¯à:¦b¤w¦³ªº¯Å§O
   ¤§¤W¯à°÷«Ø¥ß¤@­Ó·sªº¯Å§O³q°T.§ó¦hªº¸ê°T½Ð°Ñ·Ó: [5]
   http://www.lartc.org/

  The Downstream(¦V¤U¶Ç¿é)

   ±qInternetµo°e¦ÜADSL modemªº¼Æ¾Ú¥]¤J¯¸©M¼Æ¾Ú¥]¥X¯¸ªºQueues¤j¦Ü¬Û¦P. ¤£
   ºÞ«ç¼Ë, queue ·|¶°¦b±zªºISP¨º¸Ì. ¦]¬°³o¼Ë±z¤j·§¤£¯àª½±µ±±¨î¼Æ¾Ú¥]¦p¦ó
   ±Æ¶¤©Î¥H­þºØ§Î¦¡¤À°tÀu¥ýÅv. ¥u¦³¤@ºØ¤èªk¨ÓÁYµu³o¸Ìªº¤ÏÀ³®É¶¡:´Á±æ¦V±z
   µo°e¼Æ¾Ú¥]ªº®É­Ô¤£­n¤Ó§Ö. ¤£©¯ªº¬O,±zµLªkª½±µ±±¨î¼Æ¾Ú¥]ªº¨ì¹F³t«×. ³o
   ¸Ì¦³¤@¨Ç¤èªk±Nµo°eªÌªº³t«×´îºC:
     * ¬G·N±N¤J¯¸¼Æ¾Ú¥]¥á±ó. TCP is designed to take full advantage of
       the available bandwidth while also avoiding congestion of the
       link. This means that during a bulk data transfer TCP will send
       more and more data until eventually a packet is dropped. TCP
       detects this and reduces it's transmission window. This cycle
       continues throughout the transfer and assures data is moved as
       quickly as possible.
     * ¾ÞÁaadvertised receive window(¼s§i±µ¦¬µ¡)- During a TCP transfer,
       the receiver sends back a continuous stream of acknowledgment
       (ACK) packets. Included in the ACK packets is a window size
       advertisement which states the maximum amount of unacknowledged
       data the receiver should send. By manipulating the window size of
       outbound ACK packets we can intentionally slow down the sender. At
       the moment there is no (free) implementation for this type of
       flow-control on Linux (however I may be working on one!).

3. ¤u§@­ì²z

   ¦³´X­Ó¨BÆJ¥i¥HÀu¤Æupstream bandwidth(¦V¤W¶Ç¿éªº±a¼e).²Ä¤@¬O±NLinux¸ô¥Ñ
   ¾¹¦ÜADSL modemªº¶Ç¿é±a¼e­°§C¨ì ADSL modem¦ÜInternetªº±a¼e¥H¤U.¦b Linux
   ¸ô¥Ñ¾¹§Î¦¨¼Æ¾Ú¥]¶¤¦C.

   ²Ä¤G,¦b¸ô¥Ñ¾¹³]©w¶¤¦CªºÀu¥ýÅv©M²Õ´¤èªk.

   §Ú­Ì±N±qtelnet , ¦h¤H³s½u¹CÀ¸¥H¤Î¥æ¤¬³nÅé¨Ó¦Ò¬d¶¤¦CªºÀu¥ýÅv.

   ¨Ï¥Î HTB ±±¨î¶¤¦C,§Ú­Ì¥i¥H¦P®É³]©w±a¼e±±¨î©M¶¤¦CÀu¥ýÅv,¨Ã¥BÀu¥ý¯Å§O¤£
   ·|¬Û¤¬¨î¬ù.

   ²Ä¤T,³]©w¨¾¤õÀð¨Ï¥Îfwmark°Ï¤À¼Æ¾Ú¥]ªº¦¸§Ç.

3.1 Throttling Outbound Traffic with Linux HTB(¨Ï¥ÎHTB±±¨î¥X¯¸³q°T)

   §Ú­Ì±N¨Ï¥ÎHTP±±¨î¼Æ¾Ú¥]¨ì¹F ADSL modem ªº³t²v, ¬°¤FÁYµu¤ÏÀ³®É¶¡,§Ú­Ì¥²
   »Ý«OÃÒ¤£¦b ADSL modem §Î¦¨­þ©È¬O¥u¦³¤@­Ó¼Æ¾Ú¥]ªº¶¤¦C.

   Note: previous claims in this section (originally named N-band
   priority queuing) were later found to be incorrect. It actually WAS
   possible to classify packets into the individual bands of the priority
   queue by only using the fwmark field, however it was poorly documented
   at the writing of version 0.1 of this document

3.2 Priority Queuing with HTB(¨Ï¥Î HTB ³]©w¶¤¦CÀu¥ýÅv)

   ²{¦b,§Ú­Ì¤´¤£ª¾¦p¦ó§¹µ½©Ê¯à, §Ú­Ì¥u¬O±N¶¤¦C±qADSL modem Âಾ¨ìLinux¸ô
   ¥Ñ¾¹¤W¦Ó¤x. ¦pªG²{¦b¦³100­Ó ¼Æ¾Ú¥]ªº´¶³q¶¤¦C¥X²{¦b·í«eªº³]©w¤¤,§Ú±N¤£
   ´±·Q¹³¥¦ªºµ²ªG, ¦ý³o¥u¬O¤@®Éªº¦M¾÷¦Ó¤x.

   HTB·í¤¤¨C­Ó¬Û¾Fªº¶¤¦C¥i¥H¤À°t¨ì¤@­ÓÀu¥ýÅv.¦b¤£¦Pªº¯Å§O·í¤¤³]©w¤£¦PªºÃþ
   «¬.¦Û±q§Ú­Ì¥i¥H¬°¨C­Ó¯Å§O³]©w¤@­Ó³Ì¤p«OÃÒ­È, §Ú­Ì´N¾Ö¦³¤F±±¨î¼Æ¾Ú¥]ªº
   ¥X¦C©Mµo°e¦¸§Ç¯à¤O. HTB¥i¥H«Ü¦n¦a°µ¨ì³oÂI¨Ã¥B¤£·|ÅýÀu¥ý¯Å¬Û¤¬¨î¬ù..

   ³]©w¤F¯Å§O¥H«á,§Ú­Ì¨Ï¥Î¹LÂo¾¹±N³q«H¶i¦æ¯Å§O¹º¤À.¦³´XºØ¤èªk¥i¥H¹ê²{,¦ý
   §Ú­Ì¥u¤¶²Ð±`¥Îªºiptables/ipchains. §Ú­Ì±N¨Ï¥Îiptables³]©w¤@¨Ç³W«h±N¤£
   ¦Pªº³q«H¹º¤J¨ì¤£¦Pªº¯Å§O·í¤¤.

3.3 ¨Ï¥Îiptables ¹º¤À¥X¯¸ªº³q°T

   Note: originally this document used ipchains to classify packets. The
   newer iptables is now used.

   ³o¸Ì¦³¤@­Ó²³æªº´y­z,¥X¯¸ªº¼Æ¾Ú¥]¦p¦ó±q0x00ªºµ¥¯Å¶}©l,¹º¤J4­Ó¤£¦Pªºµ¥
   ¯Å·í¤¤:
     * ±N©Ò¦³¼Æ¾Ú¥]ªº¯Å§O³]¬°0x03,³o¬O³Ì§Cªº¯Å§O.
     * ±NICMPªº¼Æ¾Ú¥]¯Å§O³]¬°0x00, ·QÅýpingªº¤ÏÀ³§ó§Ö,´N¥²»Ý±o¨ì³Ì°ª¯Å§O
       ªºÀu¥ýÅv.
     * ±N©Ò¦³µo©¹¥Ø¼ÐºÝ¤f¬°25ªº¼Æ¾Ú¥]¯Å§O³]©w¬°0x03,¦pªG¦³½Öµo°eªºe-mail
       ±a¦³¤@­Ó«Ü¤jªºªþ¥ó, §Ú­Ìªº³q°T´N·|¹³³´¤Jªh¿A¤@¼Ë¤o¨BÃø¦æ, ·íµM,§Ú
       ­Ì¨Ã¤£·Q¨º¼Ë.
     * ±N©Ò¦³µo©¹¹CÀ¸ªA°È¾¹ªº¼Æ¾Ú¥]¯Å§O³]©w¬°0x02,³o±Nµ¹¹CÀ¸¤@­Ó¾A¤¤ªº¤Ï
       À³®É¶¡. but will keep them from swamping out the system
       applications that require low latency.
     * ±N©Ò¦³µo©¹¥Ø¼ÐºÝ¤f¬°1024©Î§ó§Cªº¼Æ¾Ú¥]¯Å§O³]©w¬°0x01,ªí¥Ü
       µ¹telnet,SSHµ¥Ãþ«¬ªº¨t²ÎªA°È´£¨ÑÀu¥ýÅv. FtpªººÝ¤f¤]¦b³o­Ó½d³ò¤§¤º.

   ±N¥ô¦ó"¸û¤p"ªº¼Æ¾Ú¥]¯Å§O³]©w¬°0x02,Outbound ACK packets from inbound
   downloads should be sent promptly to assure efficient downloads. This
   is possible using the iptables length module.

   ·íµM,¥¦ÁÙ¥i¥H¨Ì¾Ú±zªº»Ý¨D¨Ó³]©w.

3.4 ÁÙ¥i¥H¦A«õ±¸¤@¤U

   ­n¥[§Ö¤ÏÀ³±z¦Ü¤Ö­n°µ¨â¥ó¥H¤Wªº¨Æ±¡. ­º¥ý, ±N³Ì¤j¶Ç¿é³æ¤¸(MTU)³]©w
   ¦b1500bytes¥H¤U, ­°§C³o­Ó­È´N·|ÁYµu¥­§¡µ¥«Ý®É¶¡, ³o·|´î»´ºôµ¸ªº­t¸ü(«ì
   ´_¤F¹ê»Ú¥i¥Îªº§]¦R¶q),¦]¬°¨C­Ó¼Æ¾Ú¥]¤¤¦³40bytesªºIP©MTCP¸ê°T. ¥t¥~¥[§Ö
   ¤ÏÀ³ªº¤èªk¬O±N¶¤¦Cªø«×ÁYµu¦Ü100¥H¤U,³o¥i¥H¬Ù¥hADSL10¬í¬Û·í©ó²MªÅ¤@
   ­Ó1500byteMTUªº®É¶¡.

3.5 Attempting to Throttle Inbound Traffic(±±¨î¤J¯¸ªº³q°T)

   ³q¹L¨Ï¥Î Intermediate Queuing Device (IMQ)¶¤¦C¤¤¶¡¥ó, §Ú­Ì¥i¥H¹³³B²z¥X
   ¯¸¼Æ¾Ú¥]¤@¼Ë±N¤J¯¸¼Æ¾Ú¥]°e¤J¶¤¦C·í¤¤. ³o­Ó®×¨Ò¤¤ªº¼Æ¾Ú¥]Àu¥ýÅv«D±`²
   ³æ. ±N¤£ÄÝ©óTCP½d³ò¤ºªº³q°T¯Å§O³]©w¬° 0x00, ÄÝ©óTCP½d³ò¤ºªº³q°T¯Å§O³]
   ©w¬° 0x01, ¤]¥i¥H±N"¸û¤p"ªºTCP¼Æ¾Ú¥]³q°T¯Å§O³]©w¬° 0x00,§Ú­Ì±N§â¼Ð·Ç
   ªºFIFO¶¤¦C¯Å§O³]©w¬° 0x00 , §Ú­Ì§âRandom Early Drop (RED) ¶¤¦C¯Å§O³]©w
   ¬°0x01 RED±N¦b¼Æ¾Ú¥]¬Ý°_¨Ó¥¢¥h±±¨îªº®É­Ô(¶¤¦C±N­n·¸¥X), ´îºC¶Ç¿é©Î±N¼Æ
   ¾Ú¥]¥á±ó. §Ú­Ì±N³Ì¤j¤Æ¤J¯¸³t²v(³t²v¤p©ó¹ê»Ú¯à°÷¹F¨ìªº).We'll also
   rate-limit both classes to some maximum inbound rate which is less
   than your true inbound speed over the ADSL modem.

3.6 ¬°¤°»ò¤J¯¸ªº³q°T­­¨î¬Ý°_¨Ó¤£«ç»ò¼Ë

   §Ú­Ì¥²»Ý­­¨î¤J¯¸ªº³q°T,¥H¨¾¤îISPªº¶¤¦C¹¡©M, ³o¼Ë¬Û·í©ó½w½Ä5¬íªº¼Æ¾Ú,
   °ÝÃD¬O²{¦b°ß¤@ªº±±¨î³~®|¬O±N¼Æ¾Ú¥]¥á±ó.³o¨Ç¼Æ¾Ú¥]¥H¸g±qADSL modedm¨º¸Ì
   ±o¨ì¤F¤@¨Ç±a¼e. ¦ý¬O³o¨Ç¼Æ¾Ú¥]«o³Q¥á±ó¤F,³o¨Ç³Q¥á±óªº¼Æ¾Ú¥]³Ì²×·|¦Y±¼
   §ó¦hªº±a¼e. ·í§Ú­Ì­­¨î³q°Tªº®É­Ô, §Ú­Ì­­¨î¤F¨Ó¦Û¥»¦aºôµ¸ªº¼Æ¾Ú¥]¶Ç°e¤ñ
   ²v. ¦]¬°¦]¬°§Ú­Ì¥á±óªº¨º¨Ç¼Æ¾Ú¥]©Ò¥H¹ê»Ú¤J¯¸ªº¶Ç°e¤ñ²v¦b¦¹¤§¤W. §Ú­Ì¹ê
   »Ú¤W­­¨îªº¤J¯¸¤ñADSL modem¹ê»Ú¯à¹F¨ìªº¤ñ²vÁÙ­n§C. ¦b¹ê»Ú·í¤¤, §Ú±N¦Û¤v
   ªº1.5mbit/s downstream ADSL ­­¨î¦b700kbit/sec ,¨Ï¥¦¯à¨Ãµo5­Ó¤U¸üªº³s
   µ². TCP·|¸Ü¶V¦h,®ö¶O¦b¥á±ó¼Æ¾Ú¥]ªº±a¼e´N¶V¦h,¨Ã¥B¼Æ²v¤ñ±zªº­­¨îÁÙ­n§C.

   §ó¦nªº³~®|¨Ó±±¨îTCP³q°T¬O¾Þ§@ TCP window, ¦ý¬O³o­Ó¦n¹³Â÷ÃD¤F(§Úª¾¹D¦³
   ¤@ºØ...)

4. °õ¦æ

4.1 Caveats

   ­­¨îµo°e¦ÜDSL modemªº¼Æ¾Ú³t²v¤£¹³¬Ý°_¦üªº¨º»ò²³æ. ¤j¦h¼Æ DSL modems
   ¥H¸g¯u¥¿¦a¦b±zªºISP¹h¹D©M linux box ¤§¶¡«Ø¥ß¤F¶Ç¿é¼Æ¾Úªº¥H¤Óºô¾ô±µ. ¤j
   ¦h¼Æªº DSL modems ¨Ï¥ÎATM§@¬°µo°e¼Æ¾Úªº³s±µ¼h. ATM Á`¬O¥H53bytes/³æ¤¸
   ªº§Î¦¡µo°e¼Æ¾Ú.³o¨Ç¼Æ¾Ú·í¤¤ªº 5bytes ¬O«H®§ÀY ,¾l¤Uªº48bytes¤~¬O¶Ç¿éªº
   ¼Æ¾Ú.¬J¨Ï±zµo°e1byteªº¼Æ¾Ú,¤]±N¦]¬°ATM Á`¬O¥H 53bytes/³æ¤¸ ªº§Î¦¡µo°e
   ¼Æ¾Ú¦Ó®ø¯Ó53bytesªº±a¼e. ³oªí¥Ü±z±Nµo°e¤@­Ó¥Ñ 0 bytes ¼Æ¾Ú + 20 bytes
   TCP ³øÀY + 20 bytes IP ³øÀY + 18 bytes ¥H¤Óºô³øÀY ²Õ¦¨ªºTCP ACK¼Æ¾Ú¥].
   ¹ê»Ú¤W,¬J¨Ï±zµo°eªº¥H¤Óºô¼Æ¾Ú¥]¥u¦³40bytesªº¦³®Ä­t¸ü (TCP and IP
   header), ³Ì¤pªº¥H¤Óºô¼Æ¾Ú¥]¦³®Ä­t¸ü¼Æ¾Ú¬O46bytes,©Ò¥H¥t¥~ªº6bytes¬OªÅ
   ªº­t¸ü. ³o·N¨ýµÛ¹ê»Ú¥H¤Óºô¼Æ¾Ú¥]¥[¤W³øÀY¬O 18 + 46 = 64 bytes. ¦bATMªº
   ³W«h¤¤,¦pªGµo°e64bytesªº¼Æ¾Ú,±z±Nµo°e¨â­ÓÁ`¦@¦û¾Ú106bytes±a¼eªºATM
   cells(³æ¤¸). ³oªí¥Ü¨Cµo°e¤@­ÓTCP ACK ¼Æ¾Ú¥], ±z·|®ö¶O±¼42bytesªº±a¼e.
   ¦pªG Linux ­pºâ DSL modem ¨Ï¥Îªº«Ê¸Ë´N¨S¤°»ò°ÝÃD¤F, ¦ý¬O, Linux ¥u­pºâ
   TCP header, IP header, ©M 14 bytes ªº MAC ¦a§}. (Linux ¤£­pºâ 4 bytes
   ªº CRC ¦]¬°³o¬O¥Î¨Ó±±¨îµwÅé¼hªº). Linux ¤£·|±N¥H¤Óºô¼Æ¾Ú¥]ªº³Ì¤p­È­pºâ
   ¬° 46 bytes, ¤]¤£·|¥h­pºâ©T©wªº ATM ³æ¤¸ªº¤j¤p.

   ³o¨Ç©Ò¦³ªº³£ªí¥Ü±z­­¨îªº¥X¯¸±a¼e¤ñ¹ê»Ú¤Wªº­n§C¤@ÂI.±z¥²»Ý§ä¨ì³Ì¾A¦X±z
   ¦Û¤vªº­­¨î­È. ¦ý¬O·í±z¤U¸ü¤@­Ó¤j¤å¥ó®Éºôµ¸ªº¤ÏÀ³®É¶¡´N·|¼Éº¦¦Ü3¬í¥H¤W.
   ¦]¬°Linux¦b±a¼e®ø¯Ó­pºâªº»~®t, ©Ò¥H³o«Ü¥iµo¥Í.

   I have been working on a solution to this problem for a few months and
   have almost settled on a solution that I will soon release to the
   public for further testing. The solution involves using a user-space
   queue instead of linux's QoS to rate-limit packets. I've basically
   implemented a simple HTB queue using linux user-space queues. This
   solution (so far) has been able to regulate outbound traffic SO WELL
   that even during a massive bulk download (several streams) and bulk
   upload (gnutella, several streams) the latency PEAKS at 400ms over my
   nominal no-traffic latency of about 15ms. For more information on this
   QoS method, subscribe to the email list for updates or check back on
   updates to this HOWTO.

4.2 Script: myshaper

   ¤U­±¬O§Ú¥Î¨Ó±±¨î¦Û¤v¸ô¥Ñ¾¹ªºscript. ¥X¯¸ªº³q°T¨Ì¾ÚÃþ«¬©ñ¤J¦Ü7­Ó¶¤¦C·í
   ¤¤. ¤J¯¸ªº³q°T©ñ¤J¦Ü¨â­Ó»PTCP¼Æ¾Ú(¦pªG¤J¯¸¼Æ¾Ú¶W¥X³t²v,TCP¼Æ¾Ú¥]´N³Q¥á
   ±ó)¦³Ãöªº¶¤¦C¤¤(lowest priority). script ·í¤¤µ¹¥Xªº³t²v¬Ý¤W¥h¤u§@±o«Ü
   ¦n,³o¬O¾A¦X§Ú¦Û¤vªº³]©w,¹ï©ó±z¨Ó»¡µ²ªG¥i¯à¤£¤j¬Û¦P.

   ³o­Ó script ¬O¦b ADSL WonderShaper ªº°ò¦¤W¼g¥X¨Óªº,½Ð°Ñ·Ó: [6]LARTC
   website.
       ______________________________________________________________

#!/bin/bash
#
# myshaper - DSL/Cable modem outbound traffic shaper and prioritizer.
#            Based on the ADSL/Cable wondershaper (www.lartc.org)
#
# Written by Dan Singletary (8/7/02)
#
# NOTE!! - This script assumes your kernel has been patched with the
#          appropriate HTB queue and IMQ patches available here:
#          (subnote: future kernels may not require patching)
#
#       http://luxik.cdi.cz/~devik/qos/htb/
#       http://luxik.cdi.cz/~patrick/imq/
#
# Configuration options for myshaper:
#  DEV    - set to ethX that connects to DSL/Cable Modem
#  RATEUP - set this to slightly lower than your
#           outbound bandwidth on the DSL/Cable Modem.
#           I have a 1500/128 DSL line and setting
#           RATEUP=90 works well for my 128kbps upstream.
#           However, your mileage may vary.
#  RATEDN - set this to slightly lower than your
#           inbound bandwidth on the DSL/Cable Modem.
#
#
#  Theory on using imq to "shape" inbound traffic:
#
#     It's impossible to directly limit the rate of data that will
#  be sent to you by other hosts on the internet.  In order to shape
#  the inbound traffic rate, we have to rely on the congestion avoidance
#  algorithms in TCP.  Because of this, WE CAN ONLY ATTEMPT TO SHAPE
#  INBOUND TRAFFIC ON TCP CONNECTIONS.  This means that any traffic that
#  is not tcp should be placed in the high-prio class, since dropping
#  a non-tcp packet will most likely result in a retransmit which will
#  do nothing but unnecessarily consume bandwidth.
#     We attempt to shape inbound TCP traffic by dropping tcp packets
#  when they overflow the HTB queue which will only pass them on at
#  a certain rate (RATEDN) which is slightly lower than the actual
#  capability of the inbound device.  By dropping TCP packets that
#  are over-rate, we are simulating the same packets getting dropped
#  due to a queue-overflow on our ISP's side.  The advantage of this
#  is that our ISP's queue will never fill because TCP will slow it's
#  transmission rate in response to the dropped packets in the assumption
#  that it has filled the ISP's queue, when in reality it has not.
#     The advantage of using a priority-based queuing discipline is
#  that we can specifically choose NOT to drop certain types of packets
#  that we place in the higher priority buckets (ssh, telnet, etc).  This
#  is because packets will always be dequeued from the lowest priority class
#  with the stipulation that packets will still be dequeued from every
#  class fairly at a minimum rate (in this script, each bucket will deliver
#  at least it's fair share of 1/7 of the bandwidth).
#
#  Reiterating main points:
#   * Dropping a tcp packet on a connection will lead to a slower rate
#     of reception for that connection due to the congestion avoidance algorith
m.
#   * We gain nothing from dropping non-TCP packets.  In fact, if they
#     were important they would probably be retransmitted anyways so we want to
#     try to never drop these packets.  This means that saturated TCP connectio
ns
#     will not negatively effect protocols that don't have a built-in retransmi
t like TCP.
#   * Slowing down incoming TCP connections such that the total inbound rate is
 less
#     than the true capability of the device (ADSL/Cable Modem) SHOULD result i
n little
#     to no packets being queued on the ISP's side (DSLAM, cable concentrator,
etc).  Since
#     these ISP queues have been observed to queue 4 seconds of data at 1500Kbp
s or 6 megabits
#     of data, having no packets queued there will mean lower latency.
#
#  Caveats (questions posed before testing):
#   * Will limiting inbound traffic in this fashion result in poor bulk TCP per
formance?
#     - Preliminary answer is no!  Seems that by prioritizing ACK packets (smal
l <64b)
#       we maximize throughput by not wasting bandwidth on retransmitted packet
s
#       that we already have.
#

# NOTE: The following configuration works well for my
# setup: 1.5M/128K ADSL via Pacific Bell Internet (SBC Global Services)

DEV=eth0
RATEUP=90
RATEDN=700  # Note that this is significantly lower than the capacity of 1500.
            # Because of this, you may not want to bother limiting inbound traf
fic
            # until a better implementation such as TCP window manipulation can
 be used.

#
# End Configuration Options
#

if [ "$1" = "status" ]
then
        echo "[qdisc]"
        tc -s qdisc show dev $DEV
        tc -s qdisc show dev imq0
        echo "[class]"
        tc -s class show dev $DEV
        tc -s class show dev imq0
        echo "[filter]"
        tc -s filter show dev $DEV
        tc -s filter show dev imq0
        echo "[iptables]"
        iptables -t mangle -L MYSHAPER-OUT -v -x 2> /dev/null
        iptables -t mangle -L MYSHAPER-IN -v -x 2> /dev/null
        exit
fi

# Reset everything to a known state (cleared)
tc qdisc del dev $DEV root    2> /dev/null > /dev/null
tc qdisc del dev imq0 root 2> /dev/null > /dev/null
iptables -t mangle -D POSTROUTING -o $DEV -j MYSHAPER-OUT 2> /dev/null > /dev/n
ull
iptables -t mangle -F MYSHAPER-OUT 2> /dev/null > /dev/null
iptables -t mangle -X MYSHAPER-OUT 2> /dev/null > /dev/null
iptables -t mangle -D PREROUTING -i $DEV -j MYSHAPER-IN 2> /dev/null > /dev/nul
l
iptables -t mangle -F MYSHAPER-IN 2> /dev/null > /dev/null
iptables -t mangle -X MYSHAPER-IN 2> /dev/null > /dev/null
ip link set imq0 down 2> /dev/null > /dev/null
rmmod imq 2> /dev/null > /dev/null

if [ "$1" = "stop" ]
then
        echo "Shaping removed on $DEV."
        exit
fi

###########################################################
#
# Outbound Shaping (limits total bandwidth to RATEUP)

# set queue size to give latency of about 2 seconds on low-prio packets
ip link set dev $DEV qlen 30

# changes mtu on the outbound device.  Lowering the mtu will result
# in lower latency but will also cause slightly lower throughput due
# to IP and TCP protocol overhead.
ip link set dev $DEV mtu 1000

# add HTB root qdisc
tc qdisc add dev $DEV root handle 1: htb default 26

# add main rate limit classes
tc class add dev $DEV parent 1: classid 1:1 htb rate ${RATEUP}kbit

# add leaf classes - We grant each class at LEAST it's "fair share" of bandwidt
h.
#                    this way no class will ever be starved by another class.
Each
#                    class is also permitted to consume all of the available ba
ndwidth
#                    if no other classes are in use.
tc class add dev $DEV parent 1:1 classid 1:20 htb rate $[$RATEUP/7]kbit ceil ${
RATEUP}kbit prio 0
tc class add dev $DEV parent 1:1 classid 1:21 htb rate $[$RATEUP/7]kbit ceil ${
RATEUP}kbit prio 1
tc class add dev $DEV parent 1:1 classid 1:22 htb rate $[$RATEUP/7]kbit ceil ${
RATEUP}kbit prio 2
tc class add dev $DEV parent 1:1 classid 1:23 htb rate $[$RATEUP/7]kbit ceil ${
RATEUP}kbit prio 3
tc class add dev $DEV parent 1:1 classid 1:24 htb rate $[$RATEUP/7]kbit ceil ${
RATEUP}kbit prio 4
tc class add dev $DEV parent 1:1 classid 1:25 htb rate $[$RATEUP/7]kbit ceil ${
RATEUP}kbit prio 5
tc class add dev $DEV parent 1:1 classid 1:26 htb rate $[$RATEUP/7]kbit ceil ${
RATEUP}kbit prio 6

# attach qdisc to leaf classes - here we at SFQ to each priority class.  SFQ in
sures that
#                                within each class connections will be treated
(almost) fairly.
tc qdisc add dev $DEV parent 1:20 handle 20: sfq perturb 10
tc qdisc add dev $DEV parent 1:21 handle 21: sfq perturb 10
tc qdisc add dev $DEV parent 1:22 handle 22: sfq perturb 10
tc qdisc add dev $DEV parent 1:23 handle 23: sfq perturb 10
tc qdisc add dev $DEV parent 1:24 handle 24: sfq perturb 10
tc qdisc add dev $DEV parent 1:25 handle 25: sfq perturb 10
tc qdisc add dev $DEV parent 1:26 handle 26: sfq perturb 10

# filter traffic into classes by fwmark - here we direct traffic into priority
class according to
#                                         the fwmark set on the packet (we set
fwmark with iptables
#                                         later).  Note that above we've set th
e default priority
#                                         class to 1:26 so unmarked packets (or
 packets marked with
#                                         unfamiliar IDs) will be defaulted to
the lowest priority
#                                         class.
tc filter add dev $DEV parent 1:0 prio 0 protocol ip handle 20 fw flowid 1:20
tc filter add dev $DEV parent 1:0 prio 0 protocol ip handle 21 fw flowid 1:21
tc filter add dev $DEV parent 1:0 prio 0 protocol ip handle 22 fw flowid 1:22
tc filter add dev $DEV parent 1:0 prio 0 protocol ip handle 23 fw flowid 1:23
tc filter add dev $DEV parent 1:0 prio 0 protocol ip handle 24 fw flowid 1:24
tc filter add dev $DEV parent 1:0 prio 0 protocol ip handle 25 fw flowid 1:25
tc filter add dev $DEV parent 1:0 prio 0 protocol ip handle 26 fw flowid 1:26

# add MYSHAPER-OUT chain to the mangle table in iptables - this sets up the tab
le we'll use
#                                                      to filter and mark packe
ts.
iptables -t mangle -N MYSHAPER-OUT
iptables -t mangle -I POSTROUTING -o $DEV -j MYSHAPER-OUT

# add fwmark entries to classify different types of traffic - Set fwmark from 2
0-26 according to
#                                                             desired class. 20
 is highest prio.
iptables -t mangle -A MYSHAPER-OUT -p tcp --sport 0:1024 -j MARK --set-mark 23
# Default for low port traffic
iptables -t mangle -A MYSHAPER-OUT -p tcp --dport 0:1024 -j MARK --set-mark 23
# ""
iptables -t mangle -A MYSHAPER-OUT -p tcp --dport 20 -j MARK --set-mark 26
# ftp-data port, low prio
iptables -t mangle -A MYSHAPER-OUT -p tcp --dport 5190 -j MARK --set-mark 23
# aol instant messenger
iptables -t mangle -A MYSHAPER-OUT -p icmp -j MARK --set-mark 20
# ICMP (ping) - high prio, impress friends
iptables -t mangle -A MYSHAPER-OUT -p udp -j MARK --set-mark 21
# DNS name resolution (small packets)
iptables -t mangle -A MYSHAPER-OUT -p tcp --dport ssh -j MARK --set-mark 22
# secure shell
iptables -t mangle -A MYSHAPER-OUT -p tcp --sport ssh -j MARK --set-mark 22
# secure shell
iptables -t mangle -A MYSHAPER-OUT -p tcp --dport telnet -j MARK --set-mark 22
# telnet (ew...)
iptables -t mangle -A MYSHAPER-OUT -p tcp --sport telnet -j MARK --set-mark 22
# telnet (ew...)
iptables -t mangle -A MYSHAPER-OUT -p ipv6-crypt -j MARK --set-mark 24
# IPSec - we don't know what the payload is though...
iptables -t mangle -A MYSHAPER-OUT -p tcp --sport http -j MARK --set-mark 25
# Local web server
iptables -t mangle -A MYSHAPER-OUT -p tcp -m length --length :64 -j MARK --set-
mark 21 # small packets (probably just ACKs)
iptables -t mangle -A MYSHAPER-OUT -m mark --mark 0 -j MARK --set-mark 26
# redundant- mark any unmarked packets as 26 (low prio)

# Done with outbound shaping
#
####################################################

echo "Outbound shaping added to $DEV.  Rate: ${RATEUP}Kbit/sec."

# uncomment following line if you only want upstream shaping.
# exit

####################################################
#
# Inbound Shaping (limits total bandwidth to RATEDN)

# make sure imq module is loaded

modprobe imq numdevs=1

ip link set imq0 up

# add qdisc - default low-prio class 1:21

tc qdisc add dev imq0 handle 1: root htb default 21

# add main rate limit classes
tc class add dev imq0 parent 1: classid 1:1 htb rate ${RATEDN}kbit

# add leaf classes - TCP traffic in 21, non TCP traffic in 20
#
tc class add dev imq0 parent 1:1 classid 1:20 htb rate $[$RATEDN/2]kbit ceil ${
RATEDN}kbit prio 0
tc class add dev imq0 parent 1:1 classid 1:21 htb rate $[$RATEDN/2]kbit ceil ${
RATEDN}kbit prio 1

# attach qdisc to leaf classes - here we at SFQ to each priority class.  SFQ in
sures that
#                                within each class connections will be treated
(almost) fairly.
tc qdisc add dev imq0 parent 1:20 handle 20: sfq perturb 10
tc qdisc add dev imq0 parent 1:21 handle 21: red limit 1000000 min 5000 max 100
000 avpkt 1000 burst 50

# filter traffic into classes by fwmark - here we direct traffic into priority
class according to
#                                         the fwmark set on the packet (we set
fwmark with iptables
#                                         later).  Note that above we've set th
e default priority
#                                         class to 1:26 so unmarked packets (or
 packets marked with
#                                         unfamiliar IDs) will be defaulted to
the lowest priority
#                                         class.
tc filter add dev imq0 parent 1:0 prio 0 protocol ip handle 20 fw flowid 1:20
tc filter add dev imq0 parent 1:0 prio 0 protocol ip handle 21 fw flowid 1:21

# add MYSHAPER-IN chain to the mangle table in iptables - this sets up the tabl
e we'll use
#                                                         to filter and mark pa
ckets.
iptables -t mangle -N MYSHAPER-IN
iptables -t mangle -I PREROUTING -i $DEV -j MYSHAPER-IN

# add fwmark entries to classify different types of traffic - Set fwmark from 2
0-26 according to
#                                                             desired class. 20
 is highest prio.
iptables -t mangle -A MYSHAPER-IN -p ! tcp -j MARK --set-mark 20              #
 Set non-tcp packets to highest priority
iptables -t mangle -A MYSHAPER-IN -p tcp -m length --length :64 -j MARK --set-m
ark 20 # short TCP packets are probably ACKs
iptables -t mangle -A MYSHAPER-IN -p tcp --dport ssh -j MARK --set-mark 20    #
 secure shell
iptables -t mangle -A MYSHAPER-IN -p tcp --sport ssh -j MARK --set-mark 20    #
 secure shell
iptables -t mangle -A MYSHAPER-IN -p tcp --dport telnet -j MARK --set-mark 20 #
 telnet (ew...)
iptables -t mangle -A MYSHAPER-IN -p tcp --sport telnet -j MARK --set-mark 20 #
 telnet (ew...)
iptables -t mangle -A MYSHAPER-IN -m mark --mark 0 -j MARK --set-mark 21
       # redundant- mark any unmarked packets as 26 (low prio)

# finally, instruct these packets to go through the imq0 we set up above
iptables -t mangle -A MYSHAPER-IN -j IMQ

# Done with inbound shaping
#
####################################################

echo "Inbound shaping added to $DEV.  Rate: ${RATEDN}Kbit/sec."
       ______________________________________________________________

5. ´ú¸Õ

   ³Ì²³æªº¤èªk¬O¥Î low-priority ªº³q°T¨Ïupstream¹¡©M.³o¨Ì¾Ú±zªº¯Å§O³]©w.
   ¤ñ¦p,±Nping©Mtelnet³q°T³]©w¬°³ÌÀu¥ý¯Å§O(lower fwmark). ¦pªG±zÅýFTP¤W¸ü
   ¹¡©M upstream ªº±a¼e, ±z¥u­nÃö¤ßping©¹¹h¹Dªº®É¶¡(on the other side of
   the DSL line) ¼W¥[¤@¨Ç¼Æ¶q¦P¨S¦³¶¤¦Cªº±¡ªp¬Û¤ñ¸û.Ping ªº¤ÏÀ³¦b 100ms
   ¥H¤U(¨Ì¾Ú±zªº³]©w). ¦pªG¦h¥X1,2¬í ,ªí¥Ü¦³¨Ç¦a¤è¤£¹ï«l.

6. OK It Works!! Now What?

   ±µ¤U¨Ó, ±µ¤U¨Ó´N¨Ï¥X±z¯à·Q±o¨ìªº¦UºØªá©Û¨Ó"¨É¨ü"¥¦±a¨Óªº¦n³B§a!

   Now that you've successfully started to manage your bandwidth, you
   should start thinking of ways to use it. After all, you're probably
   paying for it!
     * Use a Gnutella client and SHARE YOUR FILES without adversely
       affecting your network performance
     * Run a web server without having web page hits slow you down in
       Quake

References

   1. http://www.tldp.org/
   2. http://jared.sonicspike.net/mailman/listinfo/adsl-qos
   3. http://luxik.cdi.cz/~devik/qos/htb/
   4. http://luxik.cdi.cz/~patrick/imq/
   5. http://www.lartc.org/
   6. http://www.lartc.org/