Wireless Mobility

Cisco Mobility

Todd LammlePresident, GlobalNet Training, inc

Sybex Author

Chapter 1

Introduction to Mobile Networks

What are Mobile Networks?

MR

Mobile Network

HA

FA

A mobile network is a stub network or subnet that uses a mobile router (MR) to achieve mobility

Nodes on the mobile networks do not need to have a Mobile IP client running

Cisco Mobile Networks -Overview

Enables always on roaming IP connectivity for entire IP networks

Nets and Subnets are mobile without devices on those subnets being aware

Standards-based solution - RFC 3344 Mobile IP and others

Mobile Router registers with Home Agent- through Foreign Agent (FA) routers- connects directly to the HA when home- Co-located Care-of Address (CCOA)

Mobile IP provides an IP node the ability to retain the same IP address and maintain uninterrupted network and application

connectivity while traveling across networks

The Benefit of Mobile IP

True Mobility

Maintaining continuous IP connectivity while crossing network boundaries, e.g. subnets or between networks

InternetHost B

Gateway A171.68.0.0

Gateway C140.31.0.0

Mobile Router171.68.69.0171.68.70.0 Mobile Router

171.68.69.0171.68.70.0

Many Networks Roaming

InternetMobile Routers

MobilityMajor Market Segments

HQ

Public AccessPublic Access

Transportation

Branch Teleworker

Enterprise/SMBEnterprise/SMB

Networks in Motion

Networks in Motion

Public SafetyCellular

Voice/DataCellular

Voice/Data

Hotel

Airports

HospitalityHospitality

ResidentialResidential

SiSi

SiSi

Internet/Service Provider Network

Defense

The Problems & Solutions of Mobility

There are a few possible ways that mobility can be achieved when a node changes links:

Host-specific routing DHCP Release/Renew Dynamic DNS Data Link layer solutions Source Routing

The Routing Table Every router has an IP routing table which it uses

to make forwarding decisions. Each route in the table has a possibility of four

columns: destination network, prefix-length, next hop and interface.

The destination and prefix length fields are used to match a packet trying to be forwarded

Three categories of entries

In a routing table, there can be three basic categories of entries:

Host specific Network prefix Default

Host Based Routes a mobile solution

It is a possible solution, but not scalable When a mobile node moves, host-specific

routes must be added, deleted or modified each time the mobile host changes links.

DHCP Release/Renew

Certainly a solution used widely today Loss of connection (nomadicity)

Dynamic DNS

How do we find a nomadic node when it keeps moving?

Typically, DNS is used to resolve a host name to an IP address

Data Link Layer Solutions

Cellular 802.11

Cellular is a wide area solution and 802.11 is a local area solution. These protocols provide homogenous mobility.

Source Routing

Uses the IP header option called the loose source and record route option

This option lists the actual intermediate destinations that a packet must visit on the path to the destination node.

This would actually be a good solution if

Tunneling (Mobile IP)

Mobile IP is a solution for mobility that is scalable, robust, secure and allows nodes to maintain application connection when changing networks.

Mobile nodes keep their existing IP address when moving from one network to another.

3200 Mobile Access Router

New Cisco IOS Software router platform that extends the IP frontier to Networks in Motion Secure data, voice and video

communications with seamless mobility across wireless networks independent of location or movement

High performance in a compact, rugged design for use in vehicles

Advanced IP services and interoperability through Cisco IOS Software

Seamless Mobility

Cell coverage

Cell coverage

Wireless LAN

coverage

Wireless LAN

coverage

Police Band

coverage

Police Band

coveragePolice

Headquarters

Uninterrupted Access = Coverage + Bandwidth

IETF Proposed Standard

Approved by the Internet Engineering Steering Group (IESG) in June 1996; published proposed standard in Nov. 1996

Mobile IP is an IETF proposed standard solution for mobility at Layer 3 IP

RFC3344 - Mobile IP RFC2003 and RFC2004 - Tunnel encapsulation RFC2005 - Mobile IP applicability RFC2006 - Mobile IP MIB

Associated RFCs RFC1701 GRE Generic Routing Encapsulation RFC3024 - Reverse Tunneling for Mobile IP

Chapter 2

Mobile IP

The Objective

Maintaining continuous IP connectivity while crossing network boundaries, e.g. subnets or

between networks

InternetHost B

Gateway A171.68.0.0

Gateway C140.31.0.0Mobile

Router171.68.69.0171.68.70.0

The Objective (Cont.)

Maintaining continuous IP connectivity while crossing network boundaries, e.g. subnets or

between networks

InternetHost B

Gateway A171.68.0.0


Router171.68.69.0171.68.70.0

Mobile Router171.68.69.0171.68.70.0

The Problem with Mobility

InternetHost B

Gateway A171.68.0.0


Router171.68.69.0171.68.70.0

The Problem with Mobility (Cont.)

InternetHost B

Gateway A171.68.0.0


Router171.68.69.0171.68.70.0

Mobile Router171.68.69.0171.68.70.0

Mobile Router171.68.69.0171.68.70.0

InternetHost B

Gateway A171.68.0.0


Router171.68.69.0171.68.70.0

Connect to171.68.69.24

Gateway A replies to Host B with an ICMP unreachable

?


Mobile Router171.68.69.0171.68.70.0

InternetHost B

Gateway A171.68.0.0


Router171.68.69.0171.68.70.0


Gateway C blocks router from joining network

SENDX

?

Gateway A replies to Host B with an ICMP unreachable


Mobile Router171.68.69.0171.68.70.0

InternetHost B

Gateway A171.68.0.0


Router171.68.69.0171.68.70.0


SENDX

Routing Protocol rejects duplicate network advertisements

Where is 171.68.69.0???

?

Gateway C blocks router from joining network Gateway A replies to Host B with an ICMP unreachable


Mobile IP Solution

InternetHost B

Home Agent171.68.60.1

Foreign AgentCOA 140.31.2.1

Mobile Router

171.68.69.0171.68.70.0

Mobile IP Solution (Cont.)

InternetHost B

Home Agent171.68.60.1Mobile

Router171.68.69.0171.68.70.0


Mobile Router171.68.69.0171.68.70.0

InternetHost B


Router171.68.69.0171.68.70.0

Mobility Binding Table:MR CoA171.68.69.1 140.31.2.1



Mobile Router sends Registration Request [RRQ] to Home Agent (HA)

Mobile Router171.68.69.0171.68.70.0



InternetHost B


Router171.68.69.0171.68.70.0




Host B sends information to Mobile Router via its Home Address Mobile Router sends Registration Request [RRQ] to Home Agent (HA)

Mobile Router171.68.69.0171.68.70.0


InternetHost B


Router171.68.69.0171.68.70.0




Home Agent forwards packets to Mobile Router via Care of Address[CoA]

Mobile Router sends Registration Request [RRQ] to Home Agent (HA)

Mobile Router171.68.69.0171.68.70.0

Host B sends information to Mobile Router via its Home Address

Mobile Router (MR) Home Agent (HA) Foreign Agent (FA) [1 Hop Away from MR] Care of Address (CoA) [Tunnel Endpoint] Correspondent Node (CN) Security Association (SA) [SPI/Key] ICMP Router Discovery Protocol (IRDP) [Advertisement] Registration Request (RRQ)

Mobile IP Terminology

MR

HA FA

CNInternet

Mobile Router is a Mobile Node

Detects Agents Registers with HA Authenticated by HA Obtains a Care-of Address

HA

FA

MR

Binding TableHost COA

65.1.1.1 30.30.30.1

65.1.1.1

FA COA 30.30.30.1

100.10.10.1 100.10.10.2

How does HA know about the Mobile Routers mobile networks?

Mobile Networks statically configured on home agent

OR sent to HA in RRQ Mobile Networks injected into home

agents routing table Routes redistributed to rest of

network Home agent tunnels packets to

mobile router via foreign agent

HA

FA

MR

65.1.1.1

FA COA 30.30.30.1

100.10.10.1 100.10.10.2

100.10.10.0/24 network can

be reached by me!

3 Steps in Operation of Mobile IP

Step 1 Agent Discovery Step 2 Registration Request Step 3 Routing

Step 1: Agent Discovery

MR1.1.1.7

FA HA

MR1.1.1.7

Step 1: Agent Discovery (Cont.)

FA HA

SolicitationSolicitation

Src AddrMR addrSrc AddrMR addr

Dest Addr224.0.0.2

Dest Addr224.0.0.2MR

1.1.1.7MR

1.1.1.7

MR sends out advertisement request (Solicitation) to all router multicast address 224.0.0.2

Step 1: Agent Discovery (Cont.)

AdvertisementIncludes COAAdvertisementIncludes COA

Src AddrFA Intfc Addr


Dest AddrMR Addr

Dest AddrMR Addr

FA HA

SolicitationSolicitation

Src AddrMR addrSrc AddrMR addr

Dest Addr224.0.0.2

Dest Addr224.0.0.2MR

1.1.1.7MR

1.1.1.7

MR sends out advertisement request (Solicitation) to all router multicast address 224.0.0.2

FA also advertises periodically

FA responds with unicast advertisement to MRResponse includes Care-of Address

Step 2: Registration Request

1.1.1.7MR

FA

1.1.1.7

HA

RRQIncludes COA from FA


Dest Port434

Src AddrMR AddrSrc AddrMR AddrSrc PortrandomSrc Portrandom

Dest AddrFA Intfc Addr

MR retrieves CoA from Advertisement and sends in RRQ

Step 2: Registration Request (Cont.)

1.1.1.7MR

FA

1.1.1.7

HA



Dest Port434

Src AddrMR AddrSrc AddrMR AddrSrc PortrandomSrc Portrandom

Dest AddrFA Intfc Addr

RRQ Includes COA

RRQ Includes COA

Dest Port434



Src Port434

Src Port434

Dest AddrHA Addr

MR retrieves CoA from Advertisement and sends in RRQ

FA checks requested services and either rejects and replies or forwards the RRQ to HA

Step 2: RRQ Reply

Home Agent HA authenticates MR Sends RRQ Reply Proxy ARPs for MR Brings up tunnel and adds

host route

RRQ ReplyRRQ Reply

Dest AddrFA

Dest AddrFA

Dest Port434

Dest Port434

Src AddrHA Intfc Addr


Src Port 434

Src Port 434

1.1.1.7MR

FA

1.1.1.7

HA

Home Agent HA authenticates MR Sends RRQ Proxy ARPs for MR Brings up tunnel and adds host

route

RRQ ReplyRRQ Reply

Dest AddrFA

Dest AddrFA

Dest Port434

Dest Port434



Src Port 434

Src Port 434

RRQ ReplyRRQ Reply

Dest AddrMR Addr

Dest AddrMR Addr Dest PortOrig PortDest PortOrig Port



Src Port 434

Src Port 434

Foreign Agent FA sees MR is

authenticated Forwards RRQ to

MR Brings up tunnel

1.1.1.7MR

FA

1.1.1.7

HA

Step 2: RRQ Reply (Cont.)

Cisco MobilityChapter 1What are Mobile Networks?MobilityMajor Market SegmentsThe Problems & Solutions of MobilityThe Routing TableThree categories of entriesHost Based Routes a mobile solutionDHCP Release/RenewDynamic DNSData Link Layer SolutionsSource RoutingTunneling (Mobile IP)Seamless MobilityChapter 2MobileIP TerminologyMobile Router is a Mobile NodeHow does HA know about the Mobile Routers mobile networks?3 Steps in Operation of Mobile IPStep 2: Registration RequestStep 2: Registration Request (Cont.)

Documents

Wireless Mobility