SIP-CONF-PULVER-2001 Telcordia Technologies Proprietary - Internal use only. See proprietary restrictions on title page. SIP-based Mobility Management Scheme for Wireless Internet Presenter: Ashutosh Dutta Research Scientist,Telcordia Technologies, NJ [email protected](Joint work with Toshiba America Research Inc., Toyota Info Technologies., Columbia University)
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SIP-CONF-PULVER-2001Telcordia Technologies Proprietary - Internal use only. See proprietary restrictions on title page.
SIP-based Mobility Management Scheme for Wireless Internet
SIP-CONF-PULVER-2001Telcordia Technologies Proprietary - Internal use only. See proprietary restrictions on title page.
Motivation
Mobility and wireless are 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 wireless mobile users in a SIP signaling and control environment.
Current Wireless Standard efforts using SIP– IETF– 3GPP (Third Generation Partnership Project)– MWIF (Mobile Wireless Internet Forum)– 3GPP2
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Outline
–Objective–Mobility Management Requirement–Existing mobility solutions–SIP based mobility–Performance–Wireless Internet Testbed Implementation–Issues and Summary–SIP Mobility demo
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Why is Mobility Management Difficult ?
Goals of mobility support in Internet:–allow a mobile device to move between different subnets
and domains –preserve an ongoing session between the mobile device
and its counterpart alive while moving–Ability to provide same service irrespective of network
attachment Several protocols and mechanisms have been developed Broadly divided into
Bit rate (indoor) 2 Mb/s 64kb/s 2Mb/sExampleapplications
Video streaming, videoconferencing
Mobile telephony File Transfer (e.g., ftp)to mobile
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State of the Art: Related Work
CellularIP
Uses host based routing 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.
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State of the Art: Related Work
Tele-MIP
TeleMIP is an intra-domain mobility solution– It uses two layers of scoping within a
domain Reduce the latency of intra-domain location
updates Reduce the frequency of global update
messages Reduce the requirement of public addresses
(IPv4)
MIP-LR
HLR can be anywhere (geographicallydistributed)
No tunneling If a VLR runs out of COAs temporarily, it
issues its own IP address as COA tunnelspackets temporarily
Lazy caching, eager caching and tunnelingfrom old foreign agent to the new one
Direct update to CH
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Related Work:
Mobile IP
Simple and scalable global mobility solution. Needs support for fast handoff control, real-time location
tracking, authentication and distributed policymanagement.
Its triangular routing may adversely affect performance ofreal-time services.
Registration and configuration are tied with the mobilityarchitecture.
There are different proposals for using mobile IP in a SIPenvironment.
- SIP based mobility for real-time services and mobileIP for TCP applications (Wedlund, Schulzrinne).
- SIP for location service and Mobile IP for addressbinding (Calhoun, Kempf).
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Qualitative comparison with Mobilityapproaches
QUALITATIVE COMPARISON OF DIFFERENT APPROACHESIntra-domainencapsulation
Inter-domainencapsulation
Changesto end-systems
Trianglerouting
Infrastructurechange
Fasthandoff
MIP Yes Yes No Yes No NoMIP-RO Yes Yes Yes No No NoMIP-RR Yes Yes No Yes No YesMIP-FF Yes Yes No Yes Yes Yes
CIP No Yes No Yes Yes YesHAWAII No Yes No Yes Yes YesMIP-LR No No Yes No No YesTeleMIP Yes Yes No Yes Yes Yes
SIP No No No No No Yes
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Objective
To develop a mobility management scheme for wireless IP networks based on SIP signaling scheme
–Support for all types of mobility–Support global roaming–Independent of underlying wireless technology–Support for real-time and non-real-time multimedia applications (both TCP and UDP/RTP based applications)
–Inter-work with today’s 1G/2G telephony smoothly
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Technical Issues for SIP Mobility
Functions Requirements
Hand-off Should support cell, subnet (intra-domain) anddomain hand-off.
Should utilize the soft hand-off feature of CDMAtechnology, or virtual hand-off
Should be wireless “technology independent”.
Registration Should be completed in less than a fewseconds.
Support Hierarchical Registration
Configuration Should be done in fractions of a second forroaming users (e.g., IP address, DNS server.)
Address Binding Should allow a user to maintain a universalidentifier regardless of its point of attachment tothe network.
Location Management Should be up to date, accurate, and confidential.
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SIP Mobility Advantages
– Easier Interaction with associated standard IETF protocols DNS, HTTP, LDAP for location management SLP for service discovery AAA protocol (e.g.;Diameter) for inter-domain mobility DHCP/DRCP for IP address configuration tftp for firware upload SDP for providing session parameters (e.g., change mid-call parameters) RTP/UDP for transport, RTSP for stream control application (e.g., IP Telephony, voice mail, streaming)
– Elimination of triangular routing and IP-IP encapsulation associated with other mobility approaches such as MIP Reduces delay Saves network overhead
End hosts should be equipped with SIP-UA Suitable for real-time multimedia traffic such as voice over IP and/or video
streaming
– Can be used for RTP/UDP based application as is
– SIP extensions for Non-real-time application Complements IPV6 mobility Can co-exist with MIP, Cellular IP and other Micro-mobility approaches
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SIP Mobility Basics
Supports end-to-end mobility by means of application layer signaling
meant for multi-media/multi-party sessions
SIP based mobility can also be termed as Application Layer mobility More than just hand-off
– supports various types of mobility
– provides flexible services
Compensate for lack of Mobile IP deployment Less reliance on underlying transport network of the ISPs Supports application-layer equivalent of Mobile IP registration Fast-handoff Paging
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–SIP Re-invite, RTP SSRC/IP address–Hierarchical proxy and RTP translator for fast hand-off within a
domain–Duration limited multicast between subnet handoff–use of RTSP to control multi-media stream
server
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Mid-session mobility for TCP based application
Mobility problem with TCP applications– TCP socket - bound to source and destination address– One of these addresses change => connection breaks
TCP applications: ftp, telnet, web Application Layer restart and recovery capabilities
– connection: close header into HTTP request– FTP variants (e.g., bullet-proof ftp)
Multi-homing feature of SCTP (IETF) TCP-Migrate Option SIP-eye enabled in the end-hosts - keeps track of the TCP end-points
of SIP
SIP Mobility Proxy (Columbia U.)– an interceptor to forward data
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Basics of SIP Mobility
Personal Mobility
– Use of one logical address to address a single user located at different terminal One address to many potential terminals
– Many addresses reaching one terminal– Use of forking Proxy, a user can be reached at any of the devices
Service Mobility– Allows users to maintain access to their services while moving or changing devices and network service
providers– Maintain speed dial list, address books, buddy lists, incoming call handling (e.g, CPL)– As part of registration message (on a routine basis or upon network change) it conveys
current network address Properties of the device (media supported, call priority etc.) Other configuration elements
Session Mobility– Allow a user to maintain an on going media session even while changing terminals– Use of MGCP/Megaco– Third-party Call control– Refer Mechanism
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SIP Mobility - Mobile IP
CH
HA
FA
Home Network
MN
Tunnelled data
data
data
CH
SIPServer
Home Network
MN
1
2
3
4
5
Plain Mobile IP
CH
SIPServer
Home Network
MNmoves MN
Foreign Network
SIP Pre-session Mobility
SIP Mid-session mobility
1
2
3
4
1. SIP INVITE 2. 302 client
moved3. SIP INVITE
4. SIP OK5. Data
1. MN moves2. MN re-invites
3. SIP OK4. Data
CH
SIPServer
Home Network
MNmoves MN
Foreign Network
SIPServer
CH
When both move
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Evaluation Model for SIP and Mobile IP
Caller’sNetwork
Callee’s Home Network
Callee’s Foreign Network
MHHA
M hops
MHFA
High-speed link
Low-speed link
N hops
CH
P hops
MIP
SIP
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SIP-Mobile IP Transport Delay vs. Packet size
SIP/MIP Latency vs. Packet size
0
10
20
30
40
50
60
70
80
90
100
0 300 600 900 1200 1500
Packet Size in bytes
La
ten
cy
in
ms
ec
MIP-SD
SIP-SD
MIP-D
SIP-D
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Bandwidth Efficiency Gain
SIP/MIP bandwidth gain
0
0.1
0.2
0.3
0.4
0.5
0.6
0 100 200 300 400 500 600
Packet size in bytes
Ban
dw
idth
Eff
icie
nc
y G
ain
SIP b/w efficiencygain
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SIP-Based Mobilityin Military Environment
CorrespondentHost
SIPServer
LDAPDNS
StreamServer
ACN 1
SIPServer
LDAPDNS
StreamServer
ACN 2
1. Register2. Invite
3. Client moved
5. INVITE Proxy message
7. Re-invite
ServerRe-directServer
ServerServer
On-going MediaSession (RTP)
DRCPDNS
192.4.8.18
MobileNode Pre-session
Move
MN
192.6.10.18
SIP
Domain 1Domain 2
6. Proxy
1B1A
Proxying Registration4. Invite
192.6.11.20MN
Mid-sessionMove
192.4.8.20
Server
CH moves
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SIP mobility for Appliances
UPnPUPnPControllerController
UPnPUPnPControllerController
JiniJiniControllerController
JiniJiniControllerController
LDAP LDAP StoreStore
Location Registries(User & Location)
Web Browser& SIP UA
PocketPC
Webphone
Web serverSIP User AgentMobile Service LogicSIP Proxy
Web serverSIP User AgentMobile Service LogicSIP Proxy
SIP ProxySIP User AgentWatcher
SIP ProxySIP User AgentWatcher
WML
SIP
http
http
SIP
ProvisioningProvisioningSystemSystem
OSGiOSGiGWGW
SIP for AppliancesSIP for Appliances
TalismanTalisman
Wide-area wireless v/dShort-range LAN I/f
Location-sensitive servicesPersonalized services
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SIP Mobility - Handoff -
BS
Correspondent Host (CH)
BS
2. re-INVITE
3. Send Data to New Address
By sending SIP re-INVITE message from new location, CH starts sending its voice packet to the new location and Communication continues seamlessly
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SIP Mobility - Handoff
Corresponding Host at Mobile Host at
IP0SIP signaling
RTP
Invite user@domain
Contact user@IP2
IP1
-> IP2
Mobile Host
SIP UA
RAT
IP2
RTP
SIP signaling
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Faster registration protocol forthe wireless roaming users,variation of DHCP
Local Authentication(Intra-domain)
BURP (Basic User RegistrationProtocol)
Takes care of movement within adomain.
Inter-domain (AAA) Diameter When mobile moves between thedomainsSIP-AAA interaction duringdomain handoff
Location Management SIP based registration scheme Re-registration upon subnethandoff
QoS DSNP Dynamically allocates the QoS
Binding SIP based mobility for real-time applicationMIP for TCP based applicationSIP Eye and Mobility ProxyWork in progress
Supports audio/video/whiteboardapplication as part of mobility
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Backbone
DiameterServer
Home AAA
Diameter Server,
visited AAAHome SIPServer
Diameter Client
BURP Server
DRCP
Server
tari.toshiba.com
Diameter Client
BURP Server
DRCP
Server
Diameter Client
BURP Server
DRCP
Server
Research.telcordia.com
12
Local SIPServer
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NGN Application Server Environment
IP
SCE
WebServer
Rapid creation of new services
Telcordia™ NGN Application Server
End-user devices
SIP
Softswitch
PSTN phone SIP phone
Service Execution
Services
MediaServer
Gateway
3rd PartyApplication Servers
API
SIP
3rd Party SIPApplication Servers
Customer Self-Service
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Services
Java
Java
IP Service Network
Service Enabling Tier
Middle Tier
Application Tier
External
B/OSS and IT
Backend
Infrastructure
InformationContent Tier
SCE
JAIN / Parlay / OSA APIs
Internet Services Gateway
Internet Services Gateway
Open IDL Interface(CORBA)
ISG APIs (Java, CORBA, XML)
ISG APIs
NGN Application Server Architecture
Location & PresenceApplications
Web PortalApplications
EnterpriseApplications
MediaServer
SIP
Open Services Gateway
Open Services Gateway
(CORBA, Java,XML)
LDAP, DIAMETER,MGCP
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Initial/Example SIP-Based Voice Services
Call Distribution / TOD routing Unattended transfer Call forward unconditional Call forward on Busy Call forward on No Answer Single line extension Find-me Call screening Simultaneous ringing Secondary number – In/Out Do not disturb Call waiting Call Hold Consultation hold
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Issues & Discussion
SIP can partially replace or complement existing mobility solutions
Survivability under dynamic network condition–When SIP server/proxy dies
Registration with Local registrar vs. home registrar Both the end hosts moving SIP for Adhoc networking Fast handoff mechanism
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Q/A
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References
www.research.telcordia.com/sip-mobile Application Layer Mobility Using SIP, MC2R
Henning Schulzrinne, Elin Wedlund
Application Layer Mobility Management Scheme for Wireless
Internet, 3G Wireless Conference
Dutta,Vakil, Baba, Chen,Tauil, Schulzrinne
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SIP Mobility Demo for real-time audio
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Morristown, NJ, U.S.A.
TARI & Telcordia
ITSUMO Outdoor Experiment
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ITSUMO Outdoor Experiment
Purpose: Under the quasi-real environment
-Mobility Test
-Total system feasibility check
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ITSUMO Outdoor Experiment
Base Station-Emulating cdma2000 by using WaveLAN
-Mobility test by using the eight radio cells
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ITSUMO Outdoor ExperimentDriving route
300 m
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ITSUMO Outdoor Experiment
Driving Experiment-Evaluation of the IP mobility
in terms of Micro, Macro and Global Mobility
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Mobile IP
Mechanism developed for the network layer to support mobility Originally intended for travelers with laptops over wired
networks Later adopted by the wireless community Maintains active TCP connections and UDP port bindings A mobile host is associated with a fixed IP address (home IP
address) When a mobile host connects to a different network other than
the one its IP address belongs, the home network forwards packets to it
A router (home agent) on the user’s home network delivers the packets to the mobile host
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Mobile IP
HomeHomeAgentAgent
ForeignForeignAgentAgent
CorrespondentHost
Home Network
Foreign Network
MobileHost
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Optimizations and Extensions to Base Mobile IP
Triangular routing causes additional delays and wastes bandwidth If the correspondent host knows where the mobile host is, it can send
packets directly to the care-of address of the mobile host Route optimization:
– binding updates sent from a home agent upon request, or – sent upon receiving a warning from a foreign agent if the mobile host
changes location during a communication session Smooth handoff:
– former foreign agent will keep forwarding packets to the new one until the correspondent host updates its mobility binding cache
Theoretically triangular routing avoided, but correspondent host must be able to encapsulate packets - not possible without changing the operating system of the correspondent host
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Optimizations and Extensions to Base Mobile IP (contd.)
Firewalls reject to forward packets coming from topologically incorrect addresses (host’s IP address does not match the network
Reverse tunneling: all packets from a mobile host go through the home agent– triangular routing again !
A mobile host registers with home agent each time it changes care-of address signaling delay for long distances
Regional registration: locally register within a visited domain– hierarchical structure of foreign agents– local foreign agents under a gateway foreign agent (GFA)– home agent registers the GFA’s address as the care-of address
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Optimizations and Extensions to Base Mobile IP (contd.)
Network Assisted, Mobile and Network Controlled (NAMONC) handoff:– Faster handoff for real-time applications– Network informs mobile host that a layer 2 handoff is anticipated– Uses simultaneous bindings (multiple registrations at a time),
sends multiple copies of the traffic to potential movement locations
Network Initiated, Mobile Terminated (NIMOT) handoff:– Foreign agents use layer 2 triggers to initiate a pre-registration
prior to receiving a formal registration request from the mobile host
Both methods assume considerable involvement of information from layer 2
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Limitations and Inefficiencies of Mobile IP
Encapsulation of packets adds between 8 or 12 bytes and 20 bytes of overhead
Although triangular routing is avoided with route optimization, with reverse tunneling it becomes a fact again
With route optimization, changes are necessary in the operating systems of the correspondent hosts
With regional registration, reliability an important issue (failure of a GFA will bring the whole hierarchy down
Processing time needed to encapsulate and decapsulate packets each time they traverse a home agent/foreign agent is not negligible especially for real-time sessions
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Cellular IP (Columbia University, Ericsson)
HomeHomeAgentAgent
CorrespondentHost
Internet(with Mobile IP)
BS
BS
BS
BS
GatewayGateway
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Cellular IP
Base stations snoop actual data packets from mobile hosts to gateway to cache the path taken by them
To route packets from the gateway to the mobile host, base stations use the reverse of this path
Hosts that have not transmitted packets for a while are removed from the routing cache of the base stations
Idle hosts send infrequent paging-update packets to the gateway– coarsely maintaining the position of idle hosts (passive connectivity)
Active hosts’ exact locations are known If an active mobile host moves to another base station during a call
– it sends a route-update packet back to the gateway– new base station(s) record this path accordingly
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HAWAII (Bell Labs)
Internet
Domain Root Domain Root RouterRouter
Domain Root Domain Root RouterRouter
BSBS
R R
R R R
BS
R R
R R
Domain 1Domain 2
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HAWAII
The path (route) between the mobile host and the domain root router is specific to that host– established (during power-up) and updated (during movement) for that
mobile host in the domain root router and intermediate routers This information is refreshed periodically by the mobile host Different path setup schemes possible to re-establish path states during
handoff– forward packets from the old base station to the new base station for a
short period (until the relevant routers update their entries for the specific host)
– do not forward packets; either bi-cast them to two base stations or unicast them for hosts that can simultaneously listen to two base stations.
HAWAII requires all routers in a domain to be augmented with mobility support so that they are able to handle host-specific path setup messages
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TeleMIP (Telcordia)
TeleMIP is an intra-domain mobility solution– It uses two layers of scoping within a domain
Reduce the latency of intra-domain location updates by specifying an intra-domain termination point (Mobility Agent or MA). – Intra-domain updates only up to the MA, which provides a
globally valid COA to mobile host. Reduce the frequency of global update messages
– Since the MA is located at a higher hierarchy than that of subnets, global updates (to HA, CHs etc.) only occur for inter-domain mobility.
Reduce the requirement of public addresses (IPv4)– By promoting a two-level addressing scheme, it promotes the
use of private (locally-scoped) addresses for handling intra-domain mobility.
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TeleMIP’s Architecture Layout
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Mobile IP with Location Registers (MIP-LR) (Telcordia, US Army)
Foreign Network: j.k.l
VLR
Mobile Host: a.b.c.d
1: Registration:COA=j.k.l.m
2: Query3: COA
4: Bindingcache (COA)
5:Un-Encapsulateddata packets sentdirectly to COA
HLR
CH
Home Network: a.b.c
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MIP-LR
HLR can be anywhere (geographically distributed) No tunneling After a mobile host moves:
– if it was registered at some other foreign VLR, the new VLR deregisters it at the old VLR.
If a VLR runs out of COAs temporarily, it issues its own IP address as COA tunnels packets temporarily
After a mobile host moves:– correspondent host will have an outdated mobility binding– a mechanism is required to update the cache on the
correspondent host: Lazy caching, eager caching and tunneling from old foreign
agent to the new one
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DHCP Enhancements for Mobile Wireless
Requirement:– Rapid client configuration(milliseconds rather than seconds)
– Automatic client reconfiguration (independent of lease time)
– Efficient use of scarce wireless bandwidth
– Allowing clients to be routers
– Enhanced registration (e.g., user identification and security)
– Flexible proxies that can act both as relay/server
– Message exchange without broadcast
How to achieve:– Shrink message size
– Minimize messages in transactions
– Minimize use of broadcast
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DRCP
DRCPDISCOVER
DRCP ADVERTISEMENT(?)
DRCPOFFER
DRCPACCEPT
ServerClientClient Server
DISCOVER
OFFER
REQUEST
ACK
ARP CHECK
ARP REPLY
15 Sec.
DHCP
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DRCP Message Flow
Client Server
ADVERTISEMENT
DISCOVER
OFFER
ACCEPT/DECLINE
Time axis
ServerClient
REQUEST/RELEASE
ACK
Client moves to a new Domain Extending the lease
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