WIRELESS FORUM IX CONFIDENTIAL A Multicast-based Protocol for IP Mobility Support Ahmed Helmy, Assist. Prof. Electrical Engineering Dept Univ. of Southern California

Multicast-based Mobility - 1 WIRELESS FORUM IX CONFIDENTIAL Outline Problem Statement Mobile IP Overview and Shortcomings Multicast and IP-Mobility Paradigm Shift: Multicast-based Mobility (M&M) Protocol Mechanisms Performance Analysis –Topology Models –Movement Models Results Future Work

Multicast-based Mobility - 2 WIRELESS FORUM IX CONFIDENTIAL Problem Statement Providing efficient IP mobility support, especially for real-time applications Real-time applications are least tolerant to jitter and so are very sensitive to handoff delays Efficiency is measured in terms of –handoff smoothness –routing efficiency (end-to-end delays) –network overhead (bandwidth consumed and links traversed)

Multicast-based Mobility - 3 WIRELESS FORUM IX CONFIDENTIAL Register (HA) Home Agent (HA) Home Network Correspondent Node (CN) Foreign Agent (FA) Foreign Network Mobile Node When mobile node (MN) moves to a foreign network it obtains a care-of-address (COA) from the foreign agent (FA) that registers it with the home agent (HA) COA is used by HA to tunnel packets to MN Solicitation Advertisement (FA,COA) Register Mobile IP Mobile Node Each mobile node has a home network, home address and home agent Packets sent by MN go directly to CN - Triangle Routing in Mobile IP: - HA may be needed to provides location hiding and security - Inefficient in terms of network overhead and end-to-end delays

Multicast-based Mobility - 4 WIRELESS FORUM IX CONFIDENTIAL Related work on Mobile IPv6 Correspondent Node Foreign Agent 2 (FA2) Mobile Node With every move, the mobile node (MN) obtains a care-of-address (COA) and sends a binding update to the HA and the CN Foreign Agent 1 (FA1) Mobile Node Solicitation Advertisement (FA1,COA1)Home Agent (HA) Home Network Binding Update (COA1) Solicitation Advertisement (FA2,COA2) Binding Update (COA2) Binding Update (COA1)

Multicast-based Mobility - 5 WIRELESS FORUM IX CONFIDENTIAL MIP.v6 (router-assisted handoff): Previous Location Approach Correspondent Node Foreign Agent 2 (FA2) Mobile Node With every move, the mobile node (MN) obtains a care-of-address (COA) and sends a binding update to the previous location/FA Foreign Agent 1 (FA1) Mobile Node Home Agent (HA) Home Network Solicitation Advertisement (FA2,COA2) Binding Update (COA2)

Multicast-based Mobility - 6 WIRELESS FORUM IX CONFIDENTIAL Multicast and IP-Mobility Common issues in both paradigms –Location independent communication/addressing –Location discovery/management –Packet forwarding Location Independent Addressing IP-Multicast –Single ‘logical’ multicast group D-class address –Senders do not know receivers –Receivers do not know senders Mobile-IP –Permanent home address –Temp care-of-address(es) –Address mapping done through the home agent

Multicast-based Mobility - 7 WIRELESS FORUM IX CONFIDENTIAL Location Management IP-Multicast –Membership location –Done thru IGMP & routing –Meet through the multicast tree Mobile-IP –Mobile node location –Done thru home agent –Meet thru registration of new address Packet Forwarding IP-Multicast –Multicast forwarding –Tunnel through the multicast tree (e.g., RP) Mobile-IP –Unicast forwarding –Tunnel through home agent

Multicast-based Mobility - 8 WIRELESS FORUM IX CONFIDENTIAL Paradigm Shift: Multicast for Mobility Instead of obtaining a new COA and registering with the new foreign agent (and subsequently with the home agent) and de-registering the old address Use the same logical multicast group address and join/leave the group as you move Potential Advantages Avoiding ‘triangle routing’ problem Avoiding the need for home/foreign agents to continuously tunnel packets to the MN Smooth hand-off using standard join/prune Using shortest path (source-specific trees)

Multicast-based Mobility - 9 WIRELESS FORUM IX CONFIDENTIAL Distribution tree dynamics while roaming CN CN: Correspondent node (sender) Wireless link Mobile Node Multicast-based Mobility (M&M): Architectural Concept

Multicast-based Mobility - 10 WIRELESS FORUM IX CONFIDENTIAL Join/Prune dynamics to modify distribution CN CN: Correspondent node (sender) Wireless link Mobile Node

Multicast-based Mobility - 11 WIRELESS FORUM IX CONFIDENTIAL Obtaining MN’s multicast address A corresponding node (CN) obtains the multicast address of the MN through: –DNS lookup similar to getting the unicast (home) address of the MN requires update of DNS after allocation of multicast addresses to MNs –Startup phase CN sends packets to home address Home agent encapsulates packets in multicast packets sent to the MN MN decapsulates these packets and sends a binding update to the CN with its multicast address

Multicast-based Mobility - 12 WIRELESS FORUM IX CONFIDENTIAL multicast Startup scenario Correspondent Node Mobile Node On first move, the mobile node (MN) sends a binding update to the CN Mobile Node Join Home Agent (HA) Home Network Join Binding Update (MN’s multicast address)

Multicast-based Mobility - 13 WIRELESS FORUM IX CONFIDENTIAL Main Protocol Mechanisms Mobile Node (MN) –Join/Leave- Movement Detection –Binding Updates- Care-of-address –Decapsulation (during start-up phase) Base Station (BS) or first hop router –Join/Leave- Caching and forwarding –Sending beacons- Election (for robustness) Correspondent Node (CN) –Binding update reception Home Agent (HA) –Encapsulation (start-up)- Election (for robustness)

Multicast-based Mobility - 14 WIRELESS FORUM IX CONFIDENTIAL Performance Evaluation: Route-based Analysis Performance metrics –Network overhead –End-to-end delay –Handoff delay The model –Topology model –Movement model –Multicast simulation (ns using centralized PIM-SM)

Multicast-based Mobility - 15 WIRELESS FORUM IX CONFIDENTIAL Topology Models Synthesized topologies –random, transit-stub using GT-ITM and Tiers topology generators –real topologies: 2 Mbone, AS, ARPA maps –21 topologies with nodes, with various avg. degrees

Multicast-based Mobility - 16 WIRELESS FORUM IX CONFIDENTIAL Movement Models If MN is visiting node n, then node n+1 is chosen according to one of the following movement patterns –Random –Neighbor: next node to visit is randomly picked from nodes directly-connected to the currently visited node –Cluster: next node is randomly picked from one of 6 nodes likely to fall within the same cluster as the current node For each movement pattern –100 movement steps in each simulation run, and 10 runs with random selection of HA and CN

Multicast-based Mobility - 17 WIRELESS FORUM IX CONFIDENTIAL - Network overhead is proportional to total number of links traversed - for Mobile IP =  (A + B), for M&M =  C - we measure ‘  (A + B) /  C’ for all simulation runs - End-to-end delay is proportional to number of links traversed in each simulation run - we define the ratio ‘r’= (A+B)/C Performance Metrics

Multicast-based Mobility - 18 WIRELESS FORUM IX CONFIDENTIAL As the MN moves from node 1 to 2, the number of added links ‘L’ is 3 and the number of links to previous location ‘P’ (shown in dashed lines) is 2. As it moves from 2 to 3 there are no added links (L=0), and P is 2. Performance Metrics (contd.)

Multicast-based Mobility - 19 WIRELESS FORUM IX CONFIDENTIAL Total links traversed.  (A + B) /  C = 1.8 Overall Network Overhead

Multicast-based Mobility - 20 WIRELESS FORUM IX CONFIDENTIAL Ratio ‘r = (A+B)/C’. Average ‘r = 2.11’. End-to-end Delay

Multicast-based Mobility - 21 WIRELESS FORUM IX CONFIDENTIAL Handoff Latency M&M: proportional To ‘L’ Mobile IP: proportional B MIPv6: proportional C Previous location: proportional P Define handoff latency ratios: – ‘B/L’, ‘C/L’ and ‘P/L’

Multicast-based Mobility - 22 WIRELESS FORUM IX CONFIDENTIAL Added links ‘L’. Average L = 2.5 Links. Handoff Latency for M&M

Multicast-based Mobility - 23 WIRELESS FORUM IX CONFIDENTIAL Average B/L, C/L and P/L ratios Handoff Latency Ratios

Multicast-based Mobility - 24 WIRELESS FORUM IX CONFIDENTIAL Conclusion M&M is quite simpler than Mobile IP (MIP) protocols. It re-uses many existing multicast mechanisms M&M performs better than MIP and is more efficient (i.e. MIP was the beginning) Extensive simulations show that on average, compared to MIP –M&M incurs ~1/2 network overhead –M&M incurs 1/2 end-to-end delay –M&M incurs less than 1/2 handoff delay

Multicast-based Mobility - 25 WIRELESS FORUM IX CONFIDENTIAL Issues and Future Work Multicast address allocation Security State overhead of the multicast tree Applicability requires ubiquitous multicast More detailed packet-level analysis (in progress) M&M for intra-domain mobility?! –Easier to manage/deploy –Per-domain authentication –Gains? Handoff performance!