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ROAM Design

Figure: Upon changing its address from $R$ to $R'$, a receiver needs only to update its trigger. This change is transparent to the sender.

In this section, we describe ROAM, which provides an end-to-end architecture for Internet host mobility on top of $i3$.

Achieving host mobility using $i3$is straightforward. A mobile host that changes its address from $R$ to $R'$ as a result of moving from one subnetwork to another can preserve end-to-end connectivity by simply updating each of its existing triggers from $(id, R)$ to $(id,
R')$, as shown in Figure 3.

ROAM exhibits the following desirable properties:

Efficient routing. ROAM takes into account the mobility pattern of the end-hosts to improve $i3$'s ability to provide low latency stretch (see Section 4.1).

Efficient handoff. ROAM implements fast handoff and multicast-based handoff to reduce packet loss during handoffs (see Section 4.2).

Fault tolerance. Since triggers are periodically refreshed, ROAM recovers gracefully from server failure. If a server fails, the triggers stored at that server are inserted at another server the next time they are refreshed.3 Section 7.1.4 evaluates ROAM's robustness through simulation.

Simultaneous mobility. The sending and receiving hosts can move simultaneously while $i3$serves as an anchor point for the two sides of the communication channel.

Location privacy. ROAM allows end-hosts the flexibility of choosing triggers to not reveal any location information. Section 4.3 discusses the tradeoffs between location privacy and routing efficiency.

Personal/session mobility. Unlike Mobile IP, ROAM allows a user to redirect a new session or migrate an active one from one application or device to another when a better choice becomes available (see Section 4.4).

Next, we describe efficient routing, efficient handoff, location privacy, and personal/session mobility in more detail. The key to achieving these properties is the ability of end-hosts to control the location of a trigger in $i3$. Since fault tolerance and simultaneous mobility follow directly from $i3$'s properties, we do not discuss them here.

next up previous
Next: Efficient Routing Up: Host Mobility Using an Previous: Implementation
Shelley Zhuang 2003-03-03