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Chapter 6.

Chapter 6. Configuring Queuing to Manage Traffic. Queuing Overview. Prioritizes traffic through router Cisco IOS offers weighted fair queuing,priority queuing, and custom queuing. IPX. SNA. IPX. IP. SNA. IP. The Need for Traffic Prioritization.

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Chapter 6.

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  1. Chapter 6. Configuring Queuing to Manage Traffic

  2. Queuing Overview • Prioritizes traffic through router • Cisco IOS offers weighted fair queuing,priority queuing, and custom queuing IPX SNA IPX IP SNA IP

  3. The Need for Traffic Prioritization • Delay-sensitive applications may require higher priority than others Interactive Traffic File Transfer

  4. Effective Use of Traffic Priorization • Priorization is most effective on bursty WAN links (T1/E1 or below) that experience temporary congestion IPX S0 IP T1/E1 AppleTalk

  5. Establishing a Queuing Policy • Determines which packets get through first • Helps provide acceptable service levels and control WAN costs Traffic Queue IPX IP AppleTalk Bottleneck

  6. Choosing a Cisco IOS Queuing Option Step1 Step2 Step3 Step4 Yes Strict control needed? Yes Yes Yes WAN congested? Custom Queuing Queuing policy? Delay OK? No No No No No need for queuing Determine traffic priorities Use weighted fair queuing Use priority queuing

  7. Configuring Weighted Fair Queuing

  8. Data Stream Classification FIFO Queuing High-Volume Traffic High-Volume Traffic Low-Volume Traffic Low-Volume Traffic

  9. Premium Gets what itneeds. StandardSharesremainingbandwidth Premium Gets what itneeds Standard Sharesremainingbandwidth Weighted Fair Queuing • Discriminates between sessions • Automatically “fairly” allocates bandwidth for each session • Priority users get needed bandwidth • Other users share remaining bandwidth Session 4 Session 3 Session 1 Session 2

  10. Fair Queuing Operation • Messages are sorted into conversations Packets in order of arrival 6 4 1 2 5 3

  11. Fair Queuing Operation (cont.) • Conversations are assigned a channel • Sorts the queu by order of the last bit crossing its channel Packets fair queued Fair queue 3 6 4 1 1 2 5 2 4 5 6 3

  12. Fair Queuing Operation (cont.) • Messages are transmitter in a fair order • High-volume conversations share the link 4 6 1 2 5 3

  13. Weighted Fair Queue Example Frame Relay Network interface Serial1 encapsulation frame-relay fair-queue 128 bandwidth 56

  14. Configuring Priority Queuing

  15. Priority Queuing S0 Packet arrives HIGH MEDIUM Priority List for S0 NORMAL Selects one of these LOW

  16. Priority Queuing Operation Incoming Packet HIGH Packet? No MEDIUMPacket? No Yes Select Queue No NORMALPacket? Yes No LOWPacket? No Yes Place in Queue Queue full? Yes Yes Yes No Dispatch Packet More? Timeout? To Queue selection Queue service WAN

  17. Priority Queuing Configuration Tasks Priority List for S0 HIGH Telnet IPX AppleTalk Default Telnet IPX AppleTalk Default To configure priority queuing perform the following tasks: 1. Create priority list based on protocol or interface 2. Assign a default queue 3. Specify the queue sizes (optional) 4. Assign the priority list to an interface MEDIUM NORMAL LOW S0

  18. Priority List Configuration Commands • Sets queue priority by protocol type Router (config) # Priority-list list-munber protocol protocol-name { high | medium | normal | low} queue/keywordkeyword-value Router (config) # Priority-list list-munber interface interface-typeinterface-number{ high | medium | normal | low} • Sets priority by incoming interface type

  19. Priority List Configuration Commands (cont.) • Assigns a default queue Router (config) # priority-list list-munber default{ high | medium | normal | low} Router (config) # priority-list list-munber queue-limit high-limit medium-limitnormal-limit low-limit • Specifies the queue sizes Router (config) # Priority-group list • Links priority list to an interafce

  20. Priority Queuing Example HIGH priority-list 1 protocol ip high tcp 23 priority-list 1 protocol appletalk medium priority-list 1 protocol ipx medium priority-list 1 protocol ip normal priority-list 1 default low ! Interface serial 0 priority-group 1 MEDIUM NORMAL LOW S0

  21. Configuring Custom Queuing

  22. Custom Queuing • Queues handled in round-robin fashion S0 0 (system) High priority (keepalive) 20 entires Default 1 Deliver x number of bytes per cycle 2 Custom Queue List for S0 3 14 15 16

  23. Custom Queuing Operation S0 Next Queue 1 Custom Queue List for S0 2 Current Queue 3 14 15 Over Service Threshold? Dispatch Packet More ? 16 Yes No To WAN Traffic Filtering Queued Message Forwarding

  24. Custom Queuing Configuration To configure custom queuing perform the following tasks: 1. Set custom queuing filtering for protocols or interfaces 2. Assign a default queue 3. Change queue capacity (optional) 4. Configure the transfer rate per queue 5. Assign the custom queue-list to an interface 1 2 3 4 Default Queue 5 . . . . 14 15 S0 16

  25. Custom Queue Configuration Commands Router(config)# queue-list list-numberprotocolprotocol-name queue-number queue-keyword keyword-value • Sets queue priority by protocol type Router(config)# queue-list list-numberinterface interface-type interface-number queue-number • Sets priority by interface type

  26. Custom Queue Configuration Commands (cont.) Router(config)# queue-list list-numberdefaultqueue-number • Assigns a default queue priority Router(config)# queue-list list-numberqueue queue-numer limit limit-number • Changes the capacity of a queue

  27. Custom Queue Configuration Commands (cont.) Router(config)# queue-list list-numberqueuequeue-number byte-count byte-count-number • Assigns a default queue priority Router(config-if)# custom-queue-list list • Assigns a queue list to an interface

  28. Custom Queuing Example 1 queue-list 1 interface E0 1 queue-list 1 protocol ip 2 queue-list 1 protocol ipx 3 queue-list 1 protocol vines 4 queue-list 1 default 5 ! interface serial 3/2 custom-queue-list 1 1 2 3 4 5 S0

  29. Custom Queuing Example 2 2 datagrams per cycle queue-list 1 protocol ip tcp 20 queue-list 1 protocol ip 2 queue-list 1 protocol ipx 3 queue-list 1 protocol vines 4 queue-list 1 default 5 queue-list 1 queue 1 byte-count 3000 ! interface serial 3/2 custom-queue-list 1 1 2 3 4 5 S0

  30. Queuing Comparison • Weighted Fair Queuing • No queue lists • Low volume given priority • Conversation dispatching • Interactive traffic gets priority • File transfers get balanced access • Enabled by default • Priority Queuing • 4 queues • High queue serviced first • Packet dispatching • Critical traffic gets through • Designed for low-bandwidth links • Custom Queuing • 16 queues • Round-robin serviced • Threshold dispatching • Allocation of available bandwidth • Best suited for high-bandwidth links

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