1. Sept 23, 2004CS573: Network Protocols and Standards1 802.1D – Expedited Traffic Network Protocols and Standards Autumn 2004-2005

2. Sept 23, 2004CS573: Network Protocols and Standards2 Expedited Traffic Preview Traffic types Network Control Voice Video Controlled Load Excellent Effort or CEO Effort Best Effort Background

3. Sept 23, 2004CS573: Network Protocols and Standards3 Traffic Types Problem: Different applications with varying data communication requirements Solutions: Design a network according to given requirements Differentiate between traffic classes For different applications, IEEE enumerated traffic types in a typical LAN environment

4. Sept 23, 2004CS573: Network Protocols and Standards4 Traffic Types: Network Control Network Control Characterized by “must get there” requirement Maintain and support the network infrastructure Placed above “voice” Meaningless to require that the [voice] traffic be delivered with a maximum delay when the correct [network] infrastructure is absent …

5. Sept 23, 2004CS573: Network Protocols and Standards5 Traffic Types: Voice Interactivity is the desired feature End-to-end delay of 100ms to 150ms What about the delay on a single LAN? 10ms is specified Data Rates are several kb/s to few tens kb/s

6. Sept 23, 2004CS573: Network Protocols and Standards6 Traffic Types: Video Interactivity may not be the required feature Specifications for Interactive video such as Video Conferencing aren’t too different from the voice specifications For non-interactive video High data rates (1Mb/s to 8Mb/s) Achieving 10ms delay is difficult LAN delay of 100ms is specified

7. Sept 23, 2004CS573: Network Protocols and Standards7 Traffic Types: Controlled Load Important business applications subject to some form of “admission control” Critical but no delay requirements Some biz applications might be more appealing if the response is better As if a user is using the network alone!!! Load on the network is fairly controlled More control on the “other” traffic Idea came from IntServ

8. Sept 23, 2004CS573: Network Protocols and Standards8 Traffic Types: Excellent Effort Excellent Effort or CEO best-effort Applicable to data traffic Requirements are traditionally not very stringent File transfer will happen… when? Some important people in a company might need faster data transfers without having to wait for long

9. Sept 23, 2004CS573: Network Protocols and Standards9 Traffic Types: Best Effort LAN traffic as we know today The default traffic class

10. Sept 23, 2004CS573: Network Protocols and Standards10 Traffic Types: Background Bulk transfers Other activities permitted on the network but should not impact the use of network by other applications Example: backups

11. Sept 23, 2004CS573: Network Protocols and Standards11 How Many Types? Every switch is not able to handle all types of traffic How many traffic types should be used? Initial answer: 2 High and Low People came up with other applications and scenarios Finally 8 levels were specified Only 7 traffic classes have been uniquely identified so far

12. Sept 23, 2004CS573: Network Protocols and Standards12 Traffic Type to User Priority Mapping User PriorityAcronymTraffic Type 1BKBackground 2--Spare 0 (default)BEBest Effort 3EEExcellent Effort 4CLControlled Load 5VIVideo 6VOVoice 7NCNetwork Control All manufacturers should agree to this mapping…

13. Sept 23, 2004CS573: Network Protocols and Standards13 User Priority Regeneration On an incoming port of a bridge, you would like to maintain the priority Not all MAC layer frame formats include priority field in their headers IEEE 802.5 token ring defines 8 priority levels Ethernet, IEEE 802.3 do not include a priority field For maximum flexibility, user priority for frames received on a given port may be regenerated according to information that is preset by management procedures

14. Sept 23, 2004CS573: Network Protocols and Standards14 Traffic Type to User Priority Mapping User PriorityDefault Regenerated Priority Range 000-7 11 22 33 44 55 66 77 User priority value for the outgoing frame should be either the value received in the frame itself (by default!) or mapped to some value in the range 0—7 (preset for that port!).

15. Sept 23, 2004CS573: Network Protocols and Standards15 Example H1 sends voice to D1 H2 sends controlled load to D2 H3 sends best effort to D2 What should Bridge B1 do?

16. Sept 23, 2004CS573: Network Protocols and Standards16 Example

17. Sept 23, 2004CS573: Network Protocols and Standards17 Example - Bridge B1 sets priority of incoming frames on port 2 (traffic type to user priority mapping) - Bridge B1 places all the frames in the outgoing queues (user priority to traffic class mapping)

18. Sept 23, 2004CS573: Network Protocols and Standards18 User Priority to Traffic Class Mapping For a given bridge, there may be more than one traffic class specified, thus one transmission queue for each traffic class Frames are assigned to the transmission queues on the basis of their user priority, using the traffic class table that is part of the state information associated with that port

19. Sept 23, 2004CS573: Network Protocols and Standards19 Recommended Traffic Type to Traffic Class Mapping #QueuesDefining Traffic Type 1BE 2 VO 3BECLVO 4BKBECLVO 5BKBECLVIVO 6BKBEEECLVIVO 7BKBEEECLVIVONC 8BK--BEEECLVIVONC

20. Sept 23, 2004CS573: Network Protocols and Standards20 Recommended User Priority to Traffic Class Mapping Number of Available Traffic Classes (Queues) 12345678 User P R I O R I T Y 000111112 100000000 200000001 300111223 401122334 501123445 601234556 701234567

21. Sept 23, 2004CS573: Network Protocols and Standards21 Example User Priority to Traffic Class Mapping The number next to the queues represents the priority class for that queue; higher values represent higher priority. The next step is to determine the frame selection and the outgoing priority of the frame Consider the previous example:

22. Sept 23, 2004CS573: Network Protocols and Standards22 Selection of Frames for Transmission According to IEEE 802.1D (portion of new 802.1D that was previously 802.1p), selection of frames for transmission is based on highest priority first Frames are selected from a given transmission queue if all the queues corresponding to numerically higher values of traffic supported by that port are empty at the time of selection Other algorithms as selected by the management may also be supported

23. Sept 23, 2004CS573: Network Protocols and Standards23 Outbound Access Priorities User Priority Outbound Access Priority for different MAC methods 8802-38802-48802-5 (usual) 8802-5 (alter) 8802-6802.9a8802-12FDDI 000040002 101141000 202242001 303343003 404444044 505555045 606656046 707667046

24. Sept 23, 2004CS573: Network Protocols and Standards24 Example Frame Selection and outbound Priority Mapping

25. Sept 23, 2004CS573: Network Protocols and Standards25 Conclusions Expedited Traffic Capabilities Not intended to provide guaranteed quality of service Allows the transmission of time critical data to be expedited when it is in competition with other non time critical data

26. Sept 23, 2004CS573: Network Protocols and Standards26 Selective Multicast: Preview Part of IEEE 802.1D standard Reasons of Selective Multicast Broadcasting of multicast traffic overloads slower links Even for high speed links, transmitting something that no one will use is not a good idea Solution Allow users to explicitly indicate their interest in receiving traffic on given multicast addresses

27. Sept 23, 2004CS573: Network Protocols and Standards27 Use of FDBs Bridges maintain filtering databases for unicast addrresses Static Entries Explicitly configured by management Dynamic Entries Automatically entered into the FDB by the normal operation of the bridge Each entry (static or dynamic) consist of: A MAC address specification A port map specifying the filtering state for that MAC address

28. Sept 23, 2004CS573: Network Protocols and Standards28 Basic Filtering Services A bridge must support these services Allow the specification of: For individual MAC addresses Static entries Dynamic entries For a specific group MAC address Static entries No static entry  Broadcast

29. Sept 23, 2004CS573: Network Protocols and Standards29 Extended Filtering Services Add the following capabilities For individual addresses Static entries may contain a value which indicates that the dynamic filtering information should be used For a specific group MAC address Static entries may contain a value which indicates that the dynamic filtering information should be used Group registration entries that are created and maintained through the use of GMRP protocol Entries corresponding to all group addresses which may not have a specific group MAC address entry OR unregistered group addresses