Supporting Mobile Wireless Internet Roaming Users in a SIP Environment

Supporting Mobile Wireless Internet Roaming Users in a SIP Environment

An SAIC Company

S. Baba&, J.-C. Chen+, A. Dutta+, N. Nakajima&, H. Schulzrinne*, Y. Shobatake&, and F. Vakil+

+Telcordia Technologies&Toshiba America Research Inc.

*Columbia University

ITSUMOTM : Internet Technology Supporting Universal Mobile Operation

hmmp.ppt– 2Telcordia Technologies Proprietary - Internal use only. See proprietary restrictions on title page.

Outline

Motivation Objective Background End-to-end Architecture HMMP (Host Mobility Management Protocol)

– Built upon SIP signaling scheme Related Work Open Issues & Future work Demo Clip (If time permits) Discussion


Motivation

Mobility is rapidly becoming the rule rather than exception. SIP is gaining acceptance as the signaling protocol for

multimedia conferences and Internet telephony.

It is essential to support mobile users in a SIP signaling and control environment.

Current Wireless Efforts– 3GPP– 3G-IP– MWIF– 3GPP2


Objectives

Present a framework, i.e., host mobility management protocol (HMMP), for supporting roaming users in a mobile wireless Internet whose signaling system is built upon SIP.

Identify possible impacts of mobility on SIP and/or other protocols.

Propose “necessary extensions” for supporting mobility with SIP.


Framework RequirementsSIP based mobility management scheme for wireless IPnetworks would support personal as well as terminal mobility support global roaming support functions such as

– hand-off – registration– configuration– address binding– location management

be independent of underlying wireless technology support real-time and non-real time multimedia applications (i.e.,

both TCP and RTP/UDP based application) inter-work with today’s 1G/2G telephony smoothly


Service Profile for all IP wireless network user

ServicesRequirements

Multimedia Voice Data

Delay Stringent Stringent TolerantLoss/error Tolerant - Stringent Tolerant StringentBit rate (outdoor) Pedestrian 384 kb/s

Vehicular 144 kb/s

64 kb/s Pedestrian 384 kb/sVehicular 144 kb/s

Bit rate (indoor) 2 Mb/s 64kb/s 2Mb/sExampleapplications

Video streaming, videoconferencing

Mobile telephony File Transfer (e.g., ftp)to mobile


The Network Architecture

MS: Mobile Station

BS: Base Station

ERC: Edge Router & Controller

Control messages (i.e., signaling)

Domain Control Agent

Visited Network

Domain Control Agent

Wireline IP backbone network

Home Network

ERC

Internet

Regional IP network Regional IP

network

ERC

Inter-Domain Control Agent

Radio Access Network(RAN)

Radio Access Network(RAN)

BS

BSBS

BS

DCADCA

IDCA

MS

IP


Network Signaling and Control Architecture

Signaling:

Wireline IP backbone network

Internet

Visiting Registrar

3GAccess

SIP

3GAccess

SIP Server

MAAAQ SIP

VR

Regional IP network

Visiting Network

MS

DCA

Home Network

3GAccess

SIP

3GAccess

Regional IP network

SIP Server

MAAAQSIP

HR

Home Registrar

DCA

Inter-Domain Registrar

SIP Server

MAAAQ

IDR

IDCA

SIP UA in mobiles and hosts.


Network Elements

Mobile Station (MS)– User terminal– Adaptive software radios, i.e., full flexibility in the frequency

band– Control and management entity

Radio Access Network (RAN)– Provides MSs with access to the wireline infrastructure.– Set of base stations (BSs) and base station controllers

(BSCs)– Adaptive software radios– May support IP routing and control functions at BSs

Open Issue under study.


Network Elements (contd.)

Edge Router & Controller (ERC)– Comprises two elements

Edge Router (ER) with one or more interfaces to provide multiple subnets

Edge Control Agent (ECA): Control and management entity

– Default router of all MSs behind it Domain Control Agent (DCA)

– connection/session management – means of interaction (i.e., signaling)

between users and network control system, and among network control entities

– MAAAQ, i.e., Mobility management, Authentication, Authorization, and Accounting (AAA), and QoS management


What is HMMP? A protocol (framework) for supporting real-time and non-real-

time multimedia applications on mobile terminals of all IP networks.

Is built on top of existing personal mobility feature of Session Initiation Protocol (SIP).

Supports– domain hand-off (i.e., roaming) and– subnet hand-off (i.e., macro mobility), and– cell hand-off (i.e., micro mobility).

If base stations are not IP based, cell hand-off details are technology dependent.

Supports both real-time and non-real-time application Spoofs constant endpoints for TCP applications of roaming users

and supports TCP as is.


HMMP Overview: Cell hand-off (A --> B)

SIP Server

MAAAQ

SIP

HR

SIP

SIP Server

MAAAQ

VR

InternetRegional IP

networkRegional IP

network

Visiting Network Home Network

BSC 1 BS

BS

ERC 1

BSC 2

BS

ERC 2

ERC 3

BS

BS BSC 3

A

C

B D

Home RegistrarVisiting Registrar

Corresponding HostSIP

207.3.232.10

207.3.232.10

207.3.240.10128.59.10.6

IPch


Cell hand-off (Micro Mobility)

Mobile moves from A to B, BSC 1– Bind the mobile’s MAC address (or CDMA sequence) to port

B– Update the label translation table in BSC 1.– Technology dependent and is done via the link layer control

channels– SIP signaling may be involved to emulate soft hand-off


HMMP Overview: Subnet hand-off (B --> C)

SIP Server

MAAAQ

HR

INFO

SIP Server

MAAAQ

VR

Internet


BSC 1 BS

BS

ERC 1

BSC 2

BS

ERC 2

ERC 3

BS

BS BSC 3

A

C

B D


Corresponding Host

DHCPDHCP

INVITE

• INFO method for address binding.

• DHCP updates the DNS.

IPch

207.3.232.10

207.3.232.10

207.3.240.10128.59.10.6


Subnet hand-off (Macro Mobility - Intra-Domain mobility)

Mobile moves further from B to C, and it is still registered with the network– The mobile asks a new temporary address from DHCP.

either directly or via a SIP registrar The DHCP gives the mobile a temporary IP address, the address of

its default gateway, and the subnet mask, nearest outbound SIP proxy server if needed

– The DHCP updates the domain name system (DNS) simultaneously for the new inbound connections

– mostly for mobile ftp/web applications

In public networks, the network may authenticate the mobile as a protection against fraud (Not a requirement).

The mobile or SIP server re-invites the corresponding host to the temporary address with new SDP parameters


Subnet hand-off (Contd.)– SIP server and network resource reservation scheme should create

a new route with adequate resources between the corresponding host and the mobile. This new route with adequate resources is only created for real-time

applications like voice. The non-real-time applications are allowed to traverse the network hop-

by-hop.

The mobile or SIP server creates a short-lived tunnel between ERC-1 and ERC-2 to reduce loss of the transient data due to hand-off.– Typically needed during hard hand-off– the mobile or SIP server informs ERC-1 to bind the previous address

of the mobile to its current one for a time-out period.This requires SIP user agents at all ERCs, and the address of the most recent ERC which is the most recent default

gateway.

– Tunnel creation is faster when both the interfaces are part of the same ERC.


HMMP Overview: Domain Hand-off ( C --> D)

SIP Server

MAAAQ

SIP

HR

SIP Server

MAAAQ

VR

Internet


BSC 1 BS

BS

ERC 1

BSC 2

BS

ERC 2

ERC 3

BS

BS BSC 3

A

C

B D



DHCPDHCP

INFO

INVITE

• Similar to Subnet hand-off plus AAA.

128.59.10.6

IPch

207.3.232.10

207.3.232.10207.3.240.10

SLA/SA


Domain Hand-off (Roaming)

Mobile moves further to D– The mobile requests for a temporary address and receives

one from DHCP. The DHCP updates the DNS simultaneously. – The mobile re-registers with its temporary address in the

new domain using the SIP REGISTER method. The mobile profile is added to the visiting registrar (VR), i.e.,

– its profile is replicated either through interaction of the VR with the HR or

– by pre-planned profile replications in the neighboring VRs.

– The mobile or SIP server re-invites the corresponding host with the new temporary address

– SIP server and network resource reservation scheme should create a new route with adequate resources between the corresponding host and the mobile.


Domain Hand-off (Roaming), …, Continued

HMMP ensures that the transient data is forwarded to the new address– The mobile or SIP server informs ERC-2 to bind the previous

address of the mobile to its current one for a time-out period. This requires SIP user agents at all ERCs, and the address of the most recent ERC which is the most recent

default gateway.


A typical Protocol Map for Inter-Domain mobility

DHCP DHCP

Domain1 Domain2

MT

MT

LocalSIPServer

PublicAAADatabase

LocalSIPServer

Network registration/ configuration

ServiceProfile

LocationDatabase

LAAADatabase

LAAADatabase

UserProfile

UserProfile

UserProfile

PublicSIPServer

1

3

55”

LocationDatabase

ServiceProfile

6’6

9

0

2

11LocationDatabaseService

Profile

10

DHCP+client

SIP client

SIP clientDHCP+

client

Service RegistrationLocation Update

Mobile moves

QoSQoS

SLA

2’

7

8

Home Visitor


Supporting TCP Applications with HMMP

SIP Server

MAAAQ

SIP

HR

SIP Server

MAAAQ

VR

Internet


BSC 1 BS

BS

ERC 1

BSC 2

BS

ERC 2

ERC 3

BS

BSC 3

A

C

B D



DHCPDHCP

SIP_EYE

Ongoing TCPConnections

INFO

INFO

INFO

• Equip MS with SIP_EYE.

IPch

207.3.232.10

207.3.232.10

207.3.240.10

128.59.10.6

IPch1


Supporting TCP Applications with HMMP A TCP connection is identified by a pair of endpoints, and each

endpoint is identified by a pair of integers (host, port).– host is IP address of the endpoint, and port is the TCP port on the host.

TCP applications– ftp, telnet, irc, web

The underlying idea of HMMP support of TCP are– SIP-Eye keeps track of ongoing TCP end-points– The MS informs the corresponding TCP endpoints about its new

address,– The corresponding host(s) bind (binds) the initial IP address of the MS

with its temporary one, and – The CH uses encapsulation to send TCP packets bearing the initial

source and destination addresses to the current location/address of the MS.

– MS does the encapsulation of its previous IP address with the new one and sends to CH


State of the Art: Related Work

CellularIP

Uses Mobile IP for global mobility. For macro-mobility it uses rules similar to HAWAII as far

as border router is concerned. It uses two parallel cache system , routing and paging, for

location update. Handoff is initiated by the mobile host

Hawaii

Proposes a 2-layer method for binding protocol. UsesMobile IP for global mobility.

For macro-mobility it assigns the mobile node an addressassociated with border router.

When moving within the foreign domain, MH retains itscare-of-address.

Base stations are capable of decapsulating packets andforwarding it to the mobile host.

Base station also determines whether to redirect theregistration to special routers in the domain or to the HA.


Related Work: Related Work

Mobile IP

Simple and scalable global mobility solution Needs support for fast handoff control, real-time location

tracking, authentication and distributed policymanagement

trust model to share a SA between 3 mobility entities Its triangular routing may adversely affect performance of

real-time services. Registration and configuration are tied with the mobility

architecture. There are different proposals for using mobile IP in a SIP

environment.- SIP based mobility for real-time services and mobile

IP for TCP applications (Wedlund, Schulzrinne).- SIP for location service and Mobile IP for address

binding (Calhoun, Kempf).


Why HMMP?Pros & Cons

Pros

No triangular routing of information, i.e., lower delay. Supports real-time and non-real-time applications.

- Needs a faster dynamic host configuration protocol. Minimizes the loss of transient data using short-lived

tunnels.- Its complexity – performance trade off require further study.

In principle, it requires no state in the network, tough isflexible enough to allow the network operator todetermine whether to maintain any state in the network.

Supports TCP as is.

Cons

Requires modification of the IP stack at hosts, MSs, androuters for encapsulation.

All hosts, MSs, and routers shall have SIP UA. It requires SIP_EYE agents in hosts and MSs.

- SIP-EYE agent can be implemented as part of the SIP-UA oras a separate entity that interacts with SIP-UA.


Possible Impact on other Protocols

It is desirable that – the SIP INFO method provides the means of profile verification

and/or replication, and address binding, – SIP registrar interacts with the AAA entity for inter-domain case– the SIP user agent is either equipped with a SIP_EYE agent or

interact with a SIP_EYE agent that maintains a record of ongoing TCP connections of the mobile, and

– the SIP user agent understands address binding INFO messages and takes necessary actions,

– Needs a faster configuration protocol (e.g., DRCP)

Either – the DHCP interacts with the DNS and updates it dynamically, or – a new protocol is developed to allow applications to use SIP

registrar for name to address and address to name mappings.


Open Issues & Future Work Proper use of the soft hand-off mechanism of the CDMA

technologies. Performance - complexity trade-off of the short-lived

tunneling between current and previous ERCs.– Other possible alternatives being looked into (e.g., SIP<->

multicast agent) Detailed specifications of the SIP_EYE agent and its relation

with the SIP UA.– Compare with other means of encapsulation method (e.g.,

closer to the base station) Interaction of the SIP Registrar with the AAA, if necessary.

– If a variant of DHCP (e.g., DRCP) is used, no interaction between AAA and Registrar is necessary.

Comparison with solutions that combines SIP & Mobile IP. A prototype of HMMP is being implemented now.


References M. Handley, H. Schulzrinne, E. Schooler, J. Rosenberg, “SIP: Session Initiation Protocol, RFC 2543 (Proposed

Standard), IETF E. Wedlund, and H. Schulzrinne, “Mobility Support using SIP” ACM WOWMOM workshop, Seattle, August 1999 F. Vakil, A. Dutta, J.-C. Chen, S. Baba, Y. Shobatake, H. Schulzrinne, “Mobility Management in a SIP Environment

Requirements, Functions and Issues”, Internet Draft March 2000, Work in Progress P. R. Calhoun, and J. Kempf, "Mobility Management and Authentication in an All-IP Network", mwif00.009, January

2000. ITSUMO Group, “ITSUMO’s All IP Wireless Architecture”, mwif00.012, January 14, 2000. A. McAuley, S. Das, and S. Baba, Y. Shobatake, “Dynamic Registration and Configuration Protocol for Mobile

Hosts”, <draft-itsumo-drcp-00.txt>, work in progress, October 1999. F. Vakil, A. Dutta, J.-C. Chen, S. Baba, and Y. Shobatake, “Host Mobility Management Protocol: Extending SIP to

3G-IP Networks”, <draft-itsumo-hmmp-00.txt>, work in progress, October 1999. S. Donavan, “ The SIP INFO Method” <draft-ietf-sip-info-method-03.txt>, March 2000, Work in Progress RFC 2004, IETF, “Minimal Encapsulation within IP” RFC 2002, IETF. “IP Mobility Support” RFC 2131, “Dynamic Host Configuration Protocol” Telcordia Technologies, “Voice Over Packet in Next Generation Networks: An Architectural Framework”, Bellcore

SR-4717, Issue 1, January 1999. ITSUMO Group, “Benchmarking of ITSUMO’s All IP Wireless Architecture”, mwif00.028, January 28, 2000. ITSUMO Group, “A Reference Architecture for All IP Wireless Networks”, 3GPP2-S00 allip-20000106-014, January

6, 2000. ITSUMO Group, “A Signaling Architecture for All IP Wireless Networks”, 3GPP2-S00allip-20000106-016, January 6,

2000. ITSUMO Group, “Evolution of Wireless Telephony towards Voice over 3G-IP”, 3GPP2- P00-19990824-010, to the

August 23, 1999.

Documents

Supporting Mobile Wireless Internet Roaming Users in a SIP Environment