IP Paging

1
IP PagingRRG related issues

• Marco Liebsch
• NEC

2
IP Paging Overview and Motivation

• Trend towards IP mobility management
• Micro-mobility solutions for known reasons
  study in RRG-MM group
• A lot of requirements on local mobility
  management solutions, as addressed in
  ltdraft-irtf-micromobility-requirements-00.txtgt
• Consider a mobile terminal, which is moving fast
  and is not involved in a communication process.
  Now see for example requirement
• 3.4 Bandwidth consumption Inefficient
  bandwidth usage due to superfluous location
  update signaling
• 3.6 Processing power Processing of frequently
  appearing protocol related packets without taking
  advantage of precise location/routing state
  maintenance. Even worse for battery powered
  mobiles!
• 3.7 Protocol states Superfluous frequent
  updating of stateful entities. Dormant mode could
  reduce updating frequency (storage
  access).Further Possibility to shift network
  dormant state to a separate entity (e.g. a Paging
  Agent (could support load sharing / state volume
  distribution).

3
IP Paging Overview and Motivation

• Optimization for nodes that are currentlynot in
  a session might be taken intoconsideration (only
  small fraction outof total population of mobiles
  is active !)
• Entering dormant mode .
• avoids frequent location updating with the
  system
• decreases the preciseness of the networks
  knowledge about individual mobiles location to
  paging areas
• implies, that at some point on an initial data
  packets path from a sender to a dormant mobile
  terminal, routing information is not
  available/up-to-date
• allows reducing interfaces sending- and
  receiving functionality
• Supports
• saving scarce radio bandwidth
• cutting superfluous location updating
• decrease the impact of moving velocity and cell
  size to protocol signaling
• reducing battery energy drainage

4
IP Paging Basic approach paging adormant
mobile terminal
Polling thepaging area
Pagingarea
Routing of initial data packet(s)
2
?
3
1
Re-establishment of routing information
Initial data packet addressing a dormant mobile
terminal
Mobile terminal
No precise routing informationavailable at some
point
5
IP Paging Characteristics

• Benefit of dormant mode and paging support
  depends on multiple parameters
• Cell size
• Mobile terminals moving velocity
• Probability of incoming calls
• Tradeoff for signaling costs w.r.t these
  parameters
• Again requirement 3.4 on bandwidth consumption
• Paging costs have to be taken into consideration
• Paging process can be optimized when appropriate
  paging strategies are deployed, like
• Blanket Polling Flooding the entire paging
  area (high costs, low latency)
• Sequential Paging Polling each location
  sequentially, possibly in decreasing order of
  probability (low signaling costs, latency might
  be large)
• others

6
IP Paging Functional entities

• Prior to optimization, requirements on IP paging
  systems should be taken into account and are
  described in RFC 3154
• RFC 3154 covers requirements and indicates
  basically three functional entities to be
  considered in an IP paging system.
• Dormant Monitoring Agent function (DMA), handles
  User-Plane tasks
• Initial user data packet reception, buffering and
  forwarding after the paging process
• Tracking Agent function (TA), tracks a mobile
  terminals location while it is dormant
• Paging Agent function (PA) handles paging the
  mobile terminal.

7
IP Paging Some routing related issues

• Basically we can distinguish
• Routing issues of control-plane (C-Plane) packets
• Routing issues of user-plane (U-Plane) packets
• U-Plane User data packet capturing buffering
  (at a reasonable location) as well as forwarding
  after routing info has beenre-established
• C-Plane Routing protocol packets for dormant
  registration, paging area updating as well as for
  polling the paging area

8
IP Paging Some routing related issues

• DMA function might be integrated with the home
  mobility agent
• TA function should then also be co-located with
  the mobility agent
• In addition Security association required
  between paging functions co-located with the
  home mobility agent and visited domain paging
  functions
• DMA/TA function might be part of the visited
  domain
• How to cope with additional stateful
  entity/entities?
• Paging process related protocol packet routing
• Multicast (difficult for dynamic paging areas)
• Unicast routing of N paging packets (signaling
  costs!)
• Dormant mode implies that the mobile has no
  global address and routing information available
  - on-link addressing?
• IPv6 Solicited Node Multicast Address
• IPv4 link-layer multicast address
• Deploy link-layer mechanisms when supported

9
IP paging Some U-Plane issues

• Reception vs. capturing of initial user data
  packets at DMA function
• Packet reception
• Advantages Potentially limits performance
  degradation compared to capturing
• Disadvantages
• Explicit DMA registration when being dormant
• Unnatural routing behavior at DMA (?) IP-IP
  encapsulated !
• Static host ID might be found in extension
  headers (routing header, inner IP packets
  destination address, )
• Packet capturing
• Advantages
• No explicit DMA registration required
• In case of MIPv6, static host ID can be found in
  the outer IP header (CoA)
• Disadvantages
• Routing state info at home mobility agent is to
  be maintained (consider mobile to be dormant!) -
  Who keeps the CoA-HoA binding alive?
• Distributed DMAs required
• Protocol (add/release) interfacing distributed
  DMAs and TA/PA required.

10
IP paging Some C-Plane issues

• Protocol signaling between a mobile terminal and
  protocol functional entities
• Direct signaling, then take into consideration
• availability of a mobile terminals address
  (when active/dormant)
• required security associations between the
  entities
• Indirect signaling,
• attendants could be deployed in Access Routers,
  link-local scope addressing possible
• Protocol mapping (!)
• IP paging framework and protocol should allow
  mapping of generic protocol functions to access
  technology specific functions for
• the paging process
• paging area updating

11
IP paging Conclusion

• Quite complex issues to be studied and evaluated
  right NOW.
• Dormant mode and paging most likely supports IP
  (local) mobility management solutions.
• See for further discussion of related issues
• http//www.ietf.org/proceedings/02mar/slides/seamo
  by-1/index.html
• Challenge Tradeoff between complexity and
  flexibility !
• Last, but not least
• Related research items to be studiedwithin the
  framework of the RRG MM groups activities ?