2. 1 © NOKIA QoS and Mobility Rajeev Koodli, Cedric Westphal and Meghana Sahasrabude Nokia Research Center Mountain View, CA

3. 2 © NOKIA Overview Background Problem scope Current work Discussion

4. 3 © NOKIA The Mobile World In the future, a major part of personal communication - be it voice, data, images or video - will be wireless. The personal mobile device will be the main medium and platform!

5. 4 © NOKIA Applications, platforms, connectivity Music Bluetooth Java Symbian MP-3 Games E-money Streaming Images Sync-ML There will be an explosion of different optimized, personalized products Location Messaging

6. 5 © NOKIA Amount and Types of Mobile Content Will Explode in the Future Types of content: User created(images, videoclips, music etc.) Personal(music, movies, movieclips, games, applications, etc.) Group(family, friends, daughter's soccer team etc.) Community(greyhound owners' image album etc.) Subscribed(Manchester United Multimedia news service etc.) Network provided(location-based weather info etc.) Images MMSsAudio/music Applications Videoclips

7. 6 © NOKIA Applications and Platform Convergence Entertainment Music, Games, Fun! Voice/SMS Calling, Messaging Imaging Multimedia Messaging Media Web Content Consumption Communicator Business Services

8. 7 © NOKIA 2002 QoS and Mobility The challenge for us: how to provide appropriate Quality of Service to applications on mobile devices.

9. 8 © NOKIA QoS and Mobility Pessimist’s view Lots of literature, little understanding Combine the two, there is even more confusion! On the other hand, the relative merits are better understood QoS is mostly Connection Admission Control (CAC) and Scheduling problem (transport issues) Mobility is a routing problem So, transport and routing interplay opens up new issues We will consider the two separately first

10. 9 © NOKIA QoS How do you provide desirable treatment for certain flows (as opposed to others) ? Connection Admission Control decides whether resources can be provided without affecting existing flows generally a hard problem: flow models, flow aggregation, end-to-end resource admission issues SLAs are typically used for exchanging traffic across operator domains; intra-domain CAC is the domain’s problem! Scheduling ensures that packet treatment (Per-Hop Behavior or PHB) is according to the admitted parameters multiple well-known scheduling algorithms, WFQ, WF 2 Q, DRR, CSFQ most vendors support multi-class queues

11. 10 © NOKIA QoS... What does QoS entail then ? Classify an incoming packet Meter (if needed) (Re)Mark the packet for appropriate treatment schedule packet for transmission means state at a router Intserv requires all Intserv-compliant nodes on the end-to-end path to have (soft) state and update it via periodic refresh messages signaling (e.g., RSVP) necessary Diffserv moves all state to the edge while leaving core routers to provide PHBs based on Behavior Aggregates signaling may be necessary at the edge

12. 11 © NOKIA Path of a packet Marker + Packet Classifier Policy Input Incoming packet To output queue Police/ Shape Meter

13. 12 © NOKIA Mobility How to allow transport protocols to use a “fixed” IP address while the device changes subnets ? IP address never changes despite movement across subnets burden on the network to route packets to topologically inconsistent addresses (host based routing) ad hoc network routing is based on host routing IP address changes when subnet prefix changes burden on the Mobile Node (MN) to ensure it receives packets; normal prefix-based routing mobile ip requires a MN to update its home network router (actually a Home Agent) to receive packets

14. 13 © NOKIA Mobility.. On some networks, link layer handles mobility to make subnet mobility transparent GPRS, UMTS Will consider mobility with IP address change in this talk GGSN SGSN PDP context activate PDP Context Update IP network

15. 14 © NOKIA Mobile IP R1 R2 MN CN Internet Visited domain HA MN: Mobile Node HA: Home Agent CN: Correspondent Node

16. 15 © NOKIA Mobility... So, what does mobility involve ? The MN should detect that it has moved to a new subnet typically done through router advertisements fast handovers allow a MN to be notified a priori MN must configure a new topologically correct IP address Inform its home network agent about its new co-ordinates The MN may directly inform its correspondent nodes There is connectivity latency and route update latency

17. 16 © NOKIA QoS and Mobility problem Since QoS implies state at a router and mobility means routing path change, how is the QoS state re-established due to mobility ? Possible approaches to solving the problem End-to-end state re-establishment (for Intserv) Only access link state re-establishment (for Diffserv) hybrid of the above two

18. 17 © NOKIA End-to-end state re-establishment Needs signaling RSVP the most well-known end-to-end QoS signaling protocol mobility-unaware; does not necessarily know that handover has happened latency before the messages are even sent mobility-blind; i.e, if an IP address changes, the flow is new end-to-end signaling admission control unable to make use of localized mobility management extensions possible; e.g., use Home Address or a ‘session- id’ in addition to the standard flow classifier nice analysis in draft-thomas-seamoby-rsvp-analysis

19. 18 © NOKIA End-to-end.. R1 R2 MN CN Signaling, data

20. 19 © NOKIA End-to-end... Mobile IP extension when a MN configures a new IP address (due to handover), it sends a Binding Update message to its Correspondent Node provides a natural point to initiate QoS signaling piggyback on Binding Update fast initiation of signaling an existing flow needs to be identified by a mobility invariant attribute such as a “session-id”, “flow-label” provides ability to make use of localized mobility signaling confined to nodes affected by mobility state re-use provides performance benefits compared to RSVP “A Framework for QoS Support in Mobile IPv6”, draft-chaskar-mobileip-qos- 01.txt, IEEE Wireless BB Summit, 2001 “QoS-Conditionalized Binding Update in Mobile IPv6”, draft-tkn-mobileip- qosbinding-mipv6-00.txt, A. Festag et al.

21. 20 © NOKIA End-to-end…. R1 R2 MN CN Signaling, data LMM domain signaling

22. 21 © NOKIA Access Link state establishment An Access Router ensures that the flow entering into the network is conformant The state at the AR may be by RSVP, ICMP or by link layer- specific mechanisms During handover, state is re-established by requiring the MN to re-initiate signaling state is transferred from an AR to another

23. 22 © NOKIA Access Link.. R1 R2 MN CN Access link signaling Context Transfer

24. 23 © NOKIA Context Transfer Mobile Nodes establish network state at their access routers AAA, QoS, Header Compression, IPSec State needs to be re-established at the new access router Transferring state during handovers saves signaling overhead over the air interface provides performance benefits for transport protocols makes handovers “seamless” “Fast Handovers and Context Transfers in Mobile Networks”, R. Koodli and C. E. Perkins, ACM CCR, October 2001 “A Context Transfer Protocol for Seamless Mobility”, draft-koodli-seamoby- ct-03.txt

25. 24 © NOKIA QoS CT QoS state established via access link signaling QoS context = {QoS Profile Type, QoS Profile} QPT = Diffserv, Intserv, Best-Effort QoS Profile = attribute values corresponding to a QPT packet classifier, meter, marker Link-specific Profile Types could also be defined “Context Relocation of QoS Parameters in IP Networks”, draft- westphal-seamoby-qos-relocate-00.txt

26. 25 © NOKIA Performance Improvement with QoS CT

27. 26 © NOKIA CT and Signaling CT works when state is restricted to an access router (or a single node) When state needs to be re-established along multiple nodes, signaling is necessary CT across access routers and signaling upstream may be useful saves air interface signaling overhead when accomplished “sufficiently in advance”, all the relevant nodes could have the state end-to-end signaling not ideal for seamless handovers

28. 27 © NOKIA Open problems New router interface capability dissemination extrapolating this at the previous router ? What should be the QoS given ? E.g., should TCP be allowed to continue with the rate before handover ? QoS authorization during handovers; how does the new router know it is allowed to support QoS for the MN ? QoS accounting state transfer

29. 28 © NOKIA QUESTIONS?? http://people.nokia.net/~rajeev,~cedric