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-rw-r--r--qos/abstract23
-rw-r--r--qos/ip-qos.mgp395
-rw-r--r--qos/qos-1.eps611
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diff --git a/qos/abstract b/qos/abstract
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+Quality of Service in IP Networks
+
+IP networks were designed some 25 years ago. Networks based on TCP/IP are
+widely deployed, as organization-local Intranets as well as in the Internet
+itself. The usage patterns of those networks change. Especially new
+technologies like voice-over-IP as well as streaming multimedia applications
+have different requirements on the underlying network infrastructure than
+bulk data transfers like ftp/www or interactive traffic like telnet/ssh.
+
+Organizations usually run a mixture of different services on their Internet
+uplinks or on their organization-internal wide area networks. Bandwidth is
+usually a limited ressource, so everybody wants to divide bandwidth between
+different services according to his specific needs.
+
+Linux always had a very strong focus on network functionality and has
+sophisticated means for bandwidth control / QoS since Kernel 2.2.
+
+The presentation is organized in the following parts:
+ Basics of QoS in IP networks
+ How can Linux help with QoS
+ Sample scenarios of Linux-based QoS solutions
+ Overview about advanced conecpts (DiffServ, IntServ, RSVP, ...)
+
diff --git a/qos/ip-qos.mgp b/qos/ip-qos.mgp
new file mode 100644
index 0000000..3960927
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+%include "cnc-style.mgp"
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+%nodefault
+%pcache 1 1 0 1
+%size 7, font "standard", fore "white", vgap 20, back "black"
+%bimage "fundo-cnc.png" 1024x768
+
+%center
+%size 7
+
+
+Quality of Service in IP Networks
+
+%center
+%size 4
+by
+
+Harald Welte <laforge@conectiva.com>
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+Contents
+
+ Definition of QoS
+
+ Why QoS
+
+ IP Networks are not designed for QoS
+
+ How to do the impossible
+
+ What can Linux based systems help
+
+ Advanced Concepts (DiffServ, IntServ, RSVP, ...)
+
+ References / Further Reading
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+Definiton of QoS
+
+ Provide Service Differentiation
+
+ Performance Assurance by
+
+ Bandwitdh guarantees
+ for streaming multimedia traffic
+ priorizing certain important applications
+
+ Latency guarantees
+ for voice over IP
+ for interactive character-oriented applications (ssh,telnet)
+
+ Packet-loss guarantees
+ for unreliable layer-4 protocols
+ to avoid retransmits
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+Why QoS
+
+
+ Decide how and who available bandwidth is devided
+
+ Limit available bandwidth for certain users / applications
+
+ Guarantee bandwidth for certain users / applications
+
+ Divide bandwidth more equally between users / applications
+
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+IP networks not designed for QoS
+
+
+Properties of IP-based networks:
+
+ offer a "best-effort" service
+
+ make NO guarantees about
+ bandwidth
+ latency
+ packet loss
+
+ provide a non-reliable packet transport
+
+Conclusion: IP networks are not suitable for QoS
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+How to do the Impossible
+
+%size 4
+
+As IP Networks including Hardware (Routers, ...) are widely deployed, all QoS efforts have to layer on top of the existing technology.
+
+ There's no real solution to control latency
+ latency widely dependent on routing, which may be dynamic
+
+ There's no real solution to control packet loss
+ packet loss may occurr on any intermediate router
+
+ But we can control bandwidth usage!
+ The sender can limit bandwidth for outgoing streams
+ Intermediate routers BEFORE a bottleneck can control bandwidth usage
+
+%size 5
+
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+What can Linux systems do?
+
+ Bandwidth limiting at the sender application
+ not many applications support it
+ server often out of control (on Internet, ...)
+ server doesn't know what's between him and the client
+
+ Bandwidth control on intermediate router before bottleneck
+ Ideal case because this is where packet loss would occurr
+ Sophisticated queue scheduling on the outgoing queue
+ Variety of different queue scheduling algorithms
+
+ Flow throttling at the Receiver
+ Worst case, because influence is limited
+ Theoretically possible for TCP, no implementation yet.
+ Ingress qdisc might help
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+Bandwidth limiting at server
+
+ Some Internet Servers support bandwidth limiting
+
+ ProFTPd (builtin support)
+
+ Apache (using contributed mod_bandwidth)
+
+
+ Using those features it is easy to limit
+
+ maximum bandwidth used per connection
+
+ maximum bandwidth used per client (IP/network)
+
+ maximum bandwidth used by one virtual host (webserver/ftpserver)
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+Router before bottleneck
+
+%size 4
+
+The router receives more packets on his incoming interface(s) than it can send out on the outgoing interface. It has to build a queue of packets (usually a FIFO one) and starts dropping packets as soon as the queue is full
+
+%image "qos-1.png" 0 100 30
+
+The idea is to change this queue, thus decide
+ which packets get enqueued in which order
+ how many packets get queued
+ which packets get dropped in case of a filling queue
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+The Linux 2.2 / 2.4 Solution
+
+ Packet Scheduling algorithms in the Kernel
+ CBQ - Class Based Queue
+ RED - Random Early Drop
+ SFQ - Stochastic Fairness Queueing
+ TEQL - True Link Equalizer
+ TBF - Token Bucket Filter
+
+ tc command of iproute2 package for configuration
+ almost no documentation
+ very few examples on the internet
+
+ Packet Classification
+ tc builtin classes (route, u23, ...)
+ all iptables/netfilter matches by using fwmark
+
+Conclusion: Linux is the best suited general-purpose operating system for QoS, but almost nobody is using it because lack of knowledge.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+Available queuing algorithms
+
+ CBQ - Class Based Queue
+ hierarchical bandwidth classes
+ used as basis in almost all cases
+ TBF - Token Bucket Filter
+ really accurate algorithm
+ uses a lot of CPU
+ not possible for high bandwidth links (>1MBit)
+ SFQ - Stochastic Fairness Queueing
+ less accurate algorithm
+ tries to distinguish between individual streams
+ does round robin between those streams
+ TEQL - True Link Equalizer
+ allows to 'bundle' interfaces
+ RED - Random Early Detect / Drop
+ simulates congested link by statistic packet dropping
+ uses almost no CPU
+ recommended for high-bandwidth backbones
+ others (WRR, TCINDEX, DSMARK, ..)
+ WRR not officially included in kernel, similar to CBQ
+ others mostly used for DiffServ
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+The big picture
+
+Overview of the a packet's journey
+
+%size 3
+%font "typewriter"
+ Incoming Packets
+%size 3
+%font "typewriter"
+ |
+%size 3
+%font "typewriter"
+ V
+%size 3
+%font "typewriter"
+ Packet Classification classify
+%size 3
+%font "typewriter"
+ (ipchains/iptables) set nfmark
+%size 3
+%font "typewriter"
+ |
+%size 3
+%font "typewriter"
+ V
+%size 3
+%font "typewriter"
+ Routing decision
+%size 3
+%font "typewriter"
+ |
+%size 3
+%font "typewriter"
+ V
+%size 3
+%font "typewriter"
+ TC filter select classes based on nfmark
+%size 3
+%font "typewriter"
+ / | \
+%size 3
+%font "typewriter"
+ / | \
+%size 3
+%font "typewriter"
+ / | \
+%size 3
+%font "typewriter"
+Different Bandwidth classes bandwidth classes (CBQ)
+%size 3
+%font "typewriter"
+ \ | /
+%size 3
+%font "typewriter"
+ \ | /
+%size 3
+%font "typewriter"
+ \ | /
+%size 3
+%font "typewriter"
+ Enqueuing output queue discipline
+%size 3
+%font "typewriter"
+ |
+%size 3
+%font "typewriter"
+ V
+%size 3
+%font "typewriter"
+ Outgoing packets
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+Example scenario usin CBQ
+
+%size 4
+Let's assume we have a link with 10 MBit maximum available bandwidth.
+We offer two major services to the outside world: Anonymous FTP and a Webserver offering important Information.
+
+FTP Bulk data transfers are using up almost all available bandwidth, thus slowing down accesses to our website :(
+
+We want to have FTP transfers use up to 8MBit and reserve 2MBit for WWW.
+
+Implementation uses CBQ for bandwidth divisions.
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+Example scenario
+
+%size 3
+ attach a CBQ to the device
+%size 3
+%font "typewriter"
+tc qdisc add dev eth0 root handle 10: cbq
+ bandwidth 10Mbit avpkt 1000
+
+%size 3
+%font "standard"
+ create CBQ classes
+%size 3
+%font "typewriter"
+tc class add dev eth0 parent 10:0 classid 10:1 cbq
+ bandwidth 10MBit rate 10MBit allot 1514
+ weight 1Mbit prio 8 maxburst 20 avpkt 1000
+
+tc class add dev eth0 parent 10:1 classid 10:100 cbq
+ bandwidth 10MBit rate 8MBit allot 1514
+ weight 800kbit prio 5 maxburst 20 avpkt 1000 bounded
+
+tc class add dev eth0 parent 10:1 classid 10:200 cbq
+ bandwidth 10MBit rate 2MBit allot 1514
+ weight 200kbit prio 5 maxburst 20 avpkt 1000 bounded
+
+%size 3
+%font "standard"
+ add filter rules
+%size 3
+%font "typewriter"
+tc filter add dev eth0 parent 10:1 protocol ip handle 6 fw classid 10:100
+
+iptables -t mangle -A PREROUTING -j MARK -p tcp --sport 20 --set-mark 6
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+Further optimization
+
+%size 4
+Now we have achieved bandwidth division between two services.
+
+Within one service, however, one individual user with a high bandwith link can still use up most of our bandwidth, slowing down other user.
+
+We can improve this behaviour of changing the scheduling algorithm from it's default (fifo)
+
+%size 3
+%font "typewriter"
+tc qdisc add dev eth0 parent 10:100 sfq quantum 1514b perturb 15
+tc qdisc add dev eth0 parent 10:200 sfq quantum 1514b perturb 15
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+QoS in IP Networks
+Further reading / Links
+
+ Bandwidth limiting on Servers
+ ProFTPd
+ http://www.proftpd.net/
+ Apache mod_bandwidth / mod_bwshare
+ ftp://ftp.cohprog.com/pub/apache/module/mod_bandwidth.c
+ http://www.topology.org/src/bwshare/
+
+ Queue scheduling
+ Advanced Routing HOWTO
+ http://www.ds9a.nl/2.4Routing/
+ Linux QoS HOWTO
+ http://www.ittc.ukans.edu/~rsarav/howto/
+ iproute2+tc
+
+ This presentation
+ Authors Homepage
+ http://www.gnumonks.org/
diff --git a/qos/qos-1.eps b/qos/qos-1.eps
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personal git repositories of Harald Welte. Your mileage may vary