TCP/IP Mobility (Network Mobility)

Transcription

1 COMP9336/4336 Mobile Data Networking or ~cs4336 TCP/IP Mobility (Network Mobility) 1

2 Lecture overview This lecture examines protocols and architectures that support mobility of an entire IP subnet. 2

3 Topics to be covered Motivation for network mobility Mobile IP based network mobility (MIP-NEMO) SIP based network mobility (SIP-NEMO) 3

4 What is network mobility? Mobile subnet Fixed subnet Consider a stub subnet Mobile subnet has moved 4

5 Motivation for supporting network mobility Commuters in trains and buses may wish to connect their devices to an onboard LAN similar to connecting to the LAN at work If the onboard LAN could remain connected to the Internet, mobility could be hidden from the commuters no individual mobility management battery power saving by not connecting to a distant outdoor radio tower (low power) 5

6 Implications The onboard IP subnet will change its point of attachment to the Internet Reachability and session continuity must be preserved despite these changes IETF has set up a working group to standardise protocols that can support subnet mobility in the TCP/IP infrastructure 6

7 Solutions We ll study two solutions MIP based or MIP-NEMO [standard from IETF] SIP based or SIP-NEMO [not a standard] Both solutions use the basic mobility standards used for host mobility In both solutions, there is an onboard central entity that manages the mobility of the onboard IP subnet onboard user devices require no action when the subnet changes point of attachment movement of the subnet remains transparent to the onboard devices 7

8 MIP-NEMO overview RFC3963 released in 2005 Onboard router (OR) uses MIP to manage the mobility of the moving subnet Bidirectional tunnel between OR and router home agent (RHA) If onboard mobile device uses MIP as well, we have a recursive MIP fixed onboard devices may not need to use MIP onboard user devices may need to use MIP 8

9 MIP-NEMO Communication with fixed onboard device HAoOR CN FR Fixed Internet FR No tunnel Single tunnel OR Uses MIP with co-located CoA FR Fixed Router Fixed onboard device does not use MIP 9

10 MIP-NEMO Communication with onboard user device HAoOU HAoOR CN Single tunnel FR Fixed Internet FR Double tunnel OR Uses MIP with co-located CoA Onboard user device uses MIP with co-located CoA HAoOU: HA of onboard user device 10

11 Multihoming with MIP-NEMO (RFC4980, Oct 2007) Connect the mobile subnet to the Internet via multiple wireless access networks Example of wireless access networks: cellular networks, WiFi, etc. All wireless interfaces can be used simultaneously Registering multiple CoA with the HA is allowed Improves reliability and robustness of the Internet connectivity 11

12 Multihoming with MIP-NEMO graphical illustration HAoOR Internet bidirectional tunnel OR has 3 CoAs Radio station for a wireless access network moving subnet 12

13 Multihoming with MIP-NEMO load balancing HAoOR Internet load balancing for download traffic OR load balancing for upload traffic moving subnet 13

14 MIP-NEMO advantages and disadvantages Same as MIP-based host mobility Advantage mobility support to upper layers Disadvantages longer route (via HA) tunneling overhead network infrastructure upgrade (HA deployment) 14

15 SIP-NEMO overview Internet Draft [not a standard] Application-layer solution No Mobile IP at network layer required Direct communication between SIP clients No triangular routing Multimedia friendly Because it uses SIP 15

16 SIP-NEMO servers Extends traditional SIP servers into: SIP-NMS (located onboard the moving subnet) SIP-HS (located in home network of SIP-NMS) SIP-FS (located in the Internet access network) Existing SIP clients can roam seamlessly between the existing and network mobility SIP domains see SIP-NEMO architecture next slide 16

17 SIP-NEMO architecture 17

18 SIP-NMS Manages mobility transparently Location and handoff management Registers its current location with SIP-HS location management of moving network Forwards registrations from onboard sip-clients to their respective home SIP servers Location management for moving SIP clients Reinvites all ongoing SIP sessions handoff management 18

19 SIP-FS Supports reinvite compression to address wireless bandwidth problem Compression done using URI lists One reinvite message from SIP-NMS to SIP- FS (wireless link) containing a list of all remote clients involved in ongoing sessions SIP-FS regenerates many reinvites from the single reinvite and sends them over the Internet 19

20 Translation of REGISTER message 20

21 Example of session establishement 21

22 Reading material RFC3963 [Mobile IP based network mobility, 2005] Internet Draft: draft-ming-sipnemo-01.txt [SIP based network mobility, 2006] Huang, Lee, Zheng, A Novel SIP-based Route Optimization for Network Mobility, IEEE Journal on Selected Areas of Communications, Vol. 24. No. 9, 2006 Yang, Huang, Chiu, Design and Implementation of Soft handoff Support for SIP-NEMO, ACM Mobility Conference, 2008, Yilan, Taiwan. 22