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Mobile IP, or TCP/IP on tour. Distribuerade system, VT2000 [email protected]. Why Mobility? IP routing, very short The need for Mobile IP. Mobile IP - Overview The Gory Details Tunneling. Future: Mobility for IPV6 Open Issues TCP performance (RSVP and Real-Time Traffic) - PowerPoint PPT Presentation
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OutlineWhy Mobility?IP routing, very
shortThe need for Mobile
IP.Mobile IP - OverviewThe Gory DetailsTunneling
Future: Mobility for IPV6
Open Issues TCP performance (RSVP and Real-
Time Traffic) Service Location
Summary and future for Mobile IP
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Mobile IP: A standard for mobile computing and networkingComputers doesn’t
stay put.Change location
without restart its application or terminating any ongoing communication
Example 1: Un-plug at campus, and plug it back at home
Example 2: Un-plug from office, let the wireless network take over
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IP NetworkingProtocol layer
Network Layer Transport Layer
What does IP do moving packets
from source to destination
No ’end-to-end’ guarantees
IP addresses Network-prefix Host portion
IP Routing Packet Header Network-prefix Every node on the
same link has the same network-prefix
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The Need for Mobile IPFig 3.1host Specific Routes (too costly)Node’s IP address (TCP fails)Link layer (Too many standards)
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Mobile IP Solves the following problemsIf a node moves
from one link to another without chnging its IP address, it will be unable to receive packets at the new link; and
If a node changes its IP address when it moves, it will have to terminate and restart any on-going communications each time it moves
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Mobile IP OverviewProposed as a
Standard in November 1996
Solution for Internet Scalable, robust,
secure, maintain communication
Use their permanent IP address
Routing protocol Route packets to
nodes that could potentially change location very rapidly
Layer 4-7, outside Mobile IP, but will be of major interest (TCP, for example)
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Reqiurements for Mobile IP; A node must be able toCommunicate wtih
other nodes after changing its link-Layer attachment to the internet.
Communicate using only its home IP address.
Communicate with other computers not using Mobile IP.
Handle security threats efficiently
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Design goals
Size and and the frequency as small as possible
Simple to implement.Aviod solutions that uses multilpe IP
adresses (Running out of IPv4 adresses
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4.7: Mobile IP Entities and Relationships (Fig. 4-1)Mobile Node (mobilen)Home Agent (Hemagent)Foreign agent (fjärragent)Home link (hemmalänk)Foreign Link (fjärrlänk)care-of-addresses (c/o, besöksadress)
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Home agentA router with an interface on the mobile
node’ home link Node keep the Home agent informed of its current
location (care-of-addresses) Advertises reachability to the network-prefix of
the mobile node’s home adress (Attracting IP adresses)
intercepts packets destined to the mobile node’s home adress and tunnels them to (c/o)
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Foreign AgentA router on a mobile node’s foreign
link which assists the mobile node in informaing its
home agent of its current (c/o) provides (c/o) adress and de-tunnels
packets (sent from the home agent) default router generated by the mobile
node.
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TunnelingAn encapsulating IP packet including a
path and an original IP packetFigure 4-2
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Definitions on ’Home’Home Adress - IP adress permanently
assigned to a mobile node (Does not change)
Home Link - network-prefix of the mobile node’s home address define its home link
Home agent - A router that has at least one interface on the mbile node’s home link
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Definitions on c/oA c/o is specific to the foreign link currently
being visited by a mobile node.A node’s c/o changes every time the mobile
node moves from one foreign link to anotherPackets desitnated to a c/o can be delivered
using existing Internet routing mechanismsA c/o is used as an exit pont of a tunnel from
the home agent toward the mobile node
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4.8: A high Level desription (Fig. 4-3)Home agents and foreign agents advertise their
presence by periodically multicasting (broadcasting) Agent advertisements
Mobile node’s listens to Agent advertisements (I am a home or away)
A mobile node connected to a foreign link acquires a c/o adress
Mobile node registers its c/o address with its home agent
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4.8: A high Level desription (Fig. 4-3) Cont:Home agent adverties reachibility to the netwrok-
prefix of the mobile node’s home link (Attracting packets sent to the mobiles home adress. Intercept these messages and tunnels them to the C/O
At C/O, the original packet is extracted from the tunnel and then delivered to the mobile node
In reverse odirection, packets sent from the mobile node are routed directly to thier destination, without need for tunneling (FA only router)
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5: The gory detailsAgent Discovery
Determines whether it is currently connected to its home link or a foreign link.
Detects whether it has moved from one link to another
obtains a care-of adress when connected to a foreign link
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5.2.1: MessagesAgent advertisements; Used by agents to
announce their capabilities to mobile nodes Agent advertisements are continuously
transmitted (multicast/broadcoast) on a specific link
Allow the mobiles to determine whether any agent is present (gets identities)
Agent solicitations; are sent by mobile that do not have the patience to wait for an Agent advertisment
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5.2.2 How does a mobile node detrmine that is has moved?Using Lifetime: Tells the mobile how soon
it should expect to hear another Agent Advertisment. AA three times faster than Lifetime
Multiple foreign agents
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5.3 What is registration A mobile node
register whenever it detects that it has chnged link from one network to another.
Reregisters when it has not moved, but when it existing registration due to expire.
Mobile IP registration is the process by which a mobile node: requests routing services from a foreign agent or foreign
link informs its home agent of its current care-of-address. Renews a registration due to expire deregisters when it returns to its home link
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5.3.1 Registration scenariosA registration consists of an exchange of a
Registration request and a Registration Reply between a mobile node and its home agent.
Three common scenarios: Using foreign agent c/o Using collocated c/o deregisters upon returning home
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5.3.2 How do nodes Process registrations Se summary
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5.3.3 How can a Mobile learn
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5.3.4. How Does
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5.4: How are the Packets routed
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5.4.6 Why the triangle routing
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5.5 SummaryAgent DiscoveryRegistrationRouting
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Tunneling: 6.1 IP Encapsulation
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Future Topics; Work in progress 12: IPv6 vs IPv4Size adresses: 128 bits vs 32 bits
No real chance of running out of adresses A single newtowrk-prefix route Autoconfigure using very simple
mechanismsLess frequently used fields in IPv4
moved into optionalIPv6 more rigorously defined (more
useful)
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12.2 Relevant to Mobile IP V6Larger adresses - No need for Foreign agents
Collocated C/O is the only one needed, snice there are sufficient IP adresses
New routing Header help Security attack (less options) Very fast forward desicion- not all routers need to
read by every router, Router Discovery Static Address Autoconfiguration -
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12.1.1 HeadersBase: Priority fields, Flow label (Real-time
traffic)Extension headers: Form a chain of
headers
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12.4 How Does it work
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12.5 How does a Mobile ...
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12.6 How Does
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12.8: IP V6 summary
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13: Open Issues. 13.1: TCP Performance and Mobility
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13.1.1: What is TCP
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13.1.2: How does TCP works
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13.1.3: Are TCP’s ..
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13.1.4: How can TCP
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13.2 RSVP and Real-Time Traffic
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13.3 Service Location
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14: SummaryBackgroundTerminologyApplying Mobile IPOpen Issues
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14: The future of Mobile IP