6610-l13- - 1 Mobile IP Puzzle 2 Who killed the white queen...

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Unformatted text preview: 1 Mobile IP Puzzle 2 Who killed the white queen? 3 Mobile IP Basics Same as the post-office analogy Two other entities – home agent (old post-office), foreign agent (new post-office) Mobile host registers with home agent the new location Home agent captures packets meant for mobile host, and forwards it to the foreign agent, which then delivers it to the mobile host 4 Reverse path? Same as in the post-office analogy Packets originating from the mobile host go directly to the static corresponding host … HA SH MH FA MH • Hence the name triangular routing 5 Mobile IP Problems? Triangular routing overhead What is the worst case scenario? Registration latency and associated problems Ingress filtering and consequences Infrastructure required for mobile IP support? Firewalls 6 Mobile IP Optimizations Route optimization Smooth hand-offs 7 Route Optimizations Enable direct notification of the corresponding host Direct tunneling from the corresponding host to the mobile host Binding cache maintained at corresponding host Management of cache not stipulated (e.g. least used entry replacement) 8 Route optimizations (contd.) 4 types of messages Binding update Binding request Binding warning Binding acknowledge 9 Binding Update When a home agent receives a packet to be tunneled to a mobile host, it sends a binding update message to the corresponding host When a home agent receives a binding request message, it replies with a binding update message Also used in the the smooth-handoffs optimization 10 Binding Update (Contd.) Corresponding host caches binding and uses it for tunneling subsequent packets Lifetime of binding? Corresponding host that perceives a near-expiry can choose to ask for a binding confirmation using the binding request message Home agent can choose to ask for an acknowledgement to which a corresponding host has to reply with a binding ack message 11 Binding warning When a foreign agent receives a tunneled message, but sees no visitor entry for the mobile host, it generates a binding warning message to the appropriate home agent When a home agent receives a warning, it issues an update message to the corresponding host What if the foreign agent does not have the home agent address (why?) ? 12 Illustration Home Agent Foreign Agent Corresponding Host Mobile Host BU BW BW BR BA 13 Smooth Hand-offs When a mobile host moves from one foreign agent to another … Packets in flight to the old FA are lost and are expected to be recovered through higher layer protocols (e.g. TCP) How can these packets be saved? 14 Smooth Hand-offs Make previous FA forward packets to the new FA Send binding updates to the old FA through the new FA Such forwarding will be done for a pre-specified amount of time (registration lifetime) Update can also help old FA free any reserved resources immediately Why better? 15...
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This note was uploaded on 12/14/2009 for the course ECE 6610 taught by Professor Staff during the Fall '08 term at Georgia Tech.

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6610-l13- - 1 Mobile IP Puzzle 2 Who killed the white queen...

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