What is Mobility Management?

● Mobility Management involves handling movement of any IP devices in a mobile environment

● Mobility Management can be

Local

Global●

Local Mobility vs Global Mobility

● Access Network An Access Network consists of following three

components: wireless or other access points, access routers, access network gateways which form the boundary to other networks

● Local Mobility Local Mobility is mobility over a restricted area of the

network topology. Local Mobility is when the mobile node moves

between different access routers in Access Network.

Contd ..

● Intra Link Mobility Intra-Link Mobility is mobility between wireless

access points within an IP Link

Is between local mobility and global mobility

● Global Mobility Global mobility involves movements across broader

administrative, geographical, and topological domains

Global mobility is when the mobile node moves from one Access Network to other

Global Mobility Management

● Global Mobility Protocol is a mobility protocol used by the mobile node to change the global, end-to-end routing of packets when movement causes a topology change and thus invalidates a global unicast address on the local IP link currently in active use by the mobile node

● Global Mobility Anchor point A node in the network where the mobile node has its

fixed home address that maintains the mapping between the home address and care-of address

contd..

● Local mobility occurs when a mobile node moves between two access points connected to two different access routers.

● Global mobility protocols allow a mobile node to maintain reachability when a change between access routers occurs, by updating the address mapping between the home address and care-of address at the global mobility anchor point .

● Global Mobility protocols hence can be used for Local Mobility but there are some problems..

Problems● Location Privacy

The change in care-of address as the mobile node moves exposes the mobile node's topological location to correspondents

● Signalling overhead including all the signalling required to configure an IP

address on the new link and global mobility protocol signalling back into the network for changing the home to care-of address mapping

Might have impact on bandwidth & performance● Update Latency

The global mobility update may require a considerable amount of time if distance b/w anchor point and correspondent node is high

Localized Mobility Management

● Localized Mobility Management is a generic term for protocols dealing with IP mobility management confined within the access network

● Localized mobility management can provide a measure of local control, so mobility management can be tuned for specialized local conditions

● Localized mobility management signalling is not routed outside the access network

Scenario's for Localized Mobility Management

● Large Campus with Diverse Physical Interconnectivity Campus wireless LAN deployment in which parts of

the campus are connected by links Campus is divided into separate IP links each served

by one or more access routers This is deployed using wireless LAN switches which

do IP mobility between them and using Localized Mobility Management at the link layer

contd..

● Advanced Cellular Network Next generation cellular protocols such as 802.16e and

Super 3G/3.9G have the potential to run IP deeper into the access network

Interoperable localized mobility management can unify local mobility across a diverse set of wireless protocols all served by IP

A standardized, interoperable LMM protocol can remove the dependence on IP layer localized mobility protocols that are specialized to specific link technologies thus reduction in cost and deployment

IETF Working Group:NETLMM

● Active group in IETF developing protocols for network based localized mobility management

● Framework Mobility anchor points within the backbone network

maintain a collection of routes for individual mobile nodes.

Packets for the mobile node are routed to and from the mobile node through the mobility anchor point

When a mobile node moves from one access router to another, the access routers send a route update to the mobility anchor point.

Contd ..

● No mobile node to network protocol will be required for Localized Mobility Management

● Functions of the protocol Handles routing update when a mobile node moves

from one access router to another within the localized mobility management domain

Handles a new mobile node that powers on or moves from another localized mobility management domain

Need for additional protocol functions might arise

Solutions for LMM

● Proposed Solutions for LMM fall into 3 categories 1) Interoperable IP level protocols that require changes to the mobile

node's IP stack and handle localized mobility management as a service provided to the host by the access network,

2) Link specific or proprietary protocols that handle localized mobility for any mobile node but only for a specific type of link layer, namely 802.11 running on an 802.3 wired network back haul.

3) Use of a standard IGP such as OSPF or IS-IS to distribute host routes, and updating the host routes when the mobile node moves.

ISSUES

● Fast Handover and latency● Security● Scalability

Latency AND Handover

● Latency arises when Mobile Node signals its peers for valid IP-Mobile Bindings,so Round Trip Time(RTT) increases and when it crosses particular delay threshold then LMM will insert some latency

● This delay in latency might account for some packet loss during communication

● Protocol operation during Mn's handover from one AR to new AR involve link switching delay,movement detection and IP Address configuration.

Types of Delay

• Propagation delay

• Link layer delay Movement detection Link resource allocation

• Network layer delay Movement detection IP address configuration Security association Location update

Proposed Solution

● The above mentioned latency can be reduced using Fast HandOver Mechanism(FHO)

● In FHO a protocol enhancement is done to allow the MN uses the previous COA(Care Of Address) until it gets registered with the new COA on its new AR

Fast Handover

● FHO mechanism involves 3 stages Handover Initialization Tunnel Establishment Packet Forwarding

Scalability

● There is a constant need for the increase in number of Mobile nodes due to increase in mobile services. So LMM function must allow for incremental development

● This requires even distribution of LMA's over a domain topology such that high concentration MN's under a single LMA (hot-spot) is prevented

● Extraneous forwarding load and routing state must be controlled through appropriate LMA selection

Topological changes

● The LMM function must be able to adapt to topological changes arising within the domain

● introduction of new LMA's within an expanding network domain is also a manifested as a topological change.

● By definition core LMA involves a single point failure because the IP-LMM involves a point of indirection.

● Can be addressed by link replication mechanisms,but it introduces additional complexities

● Dynamic anycast routing was proposed as a solution to deal with these problems

Extent of LMM Function

● An LMM mechanism ideally must not inject any additional LMM functionality to MN because this places additional complexities

● The MN must afford extra functionality to manage regional IP state

● So mobile node might need functional extensions,however LMM mechanism should refrain from involving MN from routing operations

Routing State

● Minimal routing state is important for a scalable LMM function implosion of routing state due to extraneous state maintained for the purposes of mobility protocols/optimizations simply guarantees unscalable mobility management

● Currently, routing state for the purposes of mobility management entails base IP mobility binding cache entries

● LMM-specific routing state must scale linearly with the number of registered MN, while confined only within LMA involved in implementing the LMM function.

Auto Configuration

● Mobile network operators and Internet service/content providers seek to minimize their total cost of ownership of their network domain

● To minimize this cost it is essential that the configuration task of the LMM function can adapt to topological changes with minimal (or no) human intervention

● A self-organising LMA constituency that caters for dynamic discovery, configuration and management while embracing resiliency with respect to state consistency or failure can address successfully meet scalability requirements.

Security

● Security is of paramount importance in any network,LMM scheme should cater for authentication mechanisms that prevent malicious deflection of traffic to a legitimate MN

● Involvement of the LMM function into end-to-end security semantics between the MN and its peers is beyond the functional scope of the protocol extension.

● Thus security associations between the MN and its peers must be considered transparent for the LMM

Contd ..

● There are two kinds of security issues involved in network-based localized mobility management

Security between the mobile node and the network

Security between network elements that participate in the network-based localized mobility management protocol

Security between the mobile node and the network

● There are two kind of threats

Localized mobility management protocols that have signalling between the mobile node and network require a security association between the mobile node and the network entity that is the target of the signalling

● Attacks :DOS Attacks

Second threat is related to Location Privacy i.e in the context of IP Mobility is not to reveal the geographical location of the mobile user

● Attacks : Man in Middle Attack

Security between Network Elements

● Basic threat is an attempt by an unauthorized party to signal a bogus mobility event

● This requires proper bidirectional authentication and authorization of network elements that participate in the network-based localized mobility management protocol

More Attacks

● Message Replay Signals that are sent by the MN can also be captured

and replayed by malicious nodes towards the LMA Thus LMA must ensure that such signals are

authenticated or have a restricted lifetime

● Denial Of Service It is possible that the LMA may receive signals that

incur redundant processing at the LMA and as a result, deprive other MN's from LMM services

The LMM function must ensure that malicious nodes are excluded from further communications with the LMA