Lecture 8 - CSCE 464 Wireless and Mobile Systems Fall 2016...

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CSCE 464: Wireless and Mobile Systems Fall 2016 Dr. Radu Stoleru
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Outline Routing in Multihop Wireless Networks: Mobile adhoc networks, mesh networks, sensor networks Mobile IP 3/28/17 2
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Mobile IP Section 6.6 in class notes.
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IP (Internet Protocol) is a Network Layer Protocol. IP’s current version is Version 6 (IPv6). It is Orientation 3/28/17 4
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IP: The waist of the hourglass IP is the waist of the hourglass of the Internet protocol architecture Multiple higher-layer protocols Multiple lower-layer protocols Only one protocol at the network layer. 3/28/17 5 Applications HTTP FTP SMTP TCP UDP IP Data link layer protocols Physical layer protocols
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Application protocol IP is the highest layer protocol which is implemented at both routers and hosts 3/28/17 6
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IP Service Delivery service of IP is minimal IP provides an unreliable connectionless best effort service (also called: “datagram service”). Unreliable: IP does not make an attempt to recover lost packets Connectionless: Each packet (“datagram”) is handled independently. IP is not aware that packets between hosts may be sent in a logical sequence Best effort: IP does not make guarantees on the service (no throughput guarantee, no delay guarantee,…) Consequences: Higher layer protocols have to deal with losses or with duplicate packets Packets may be delivered out-of-sequence 3/28/17 7
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IP supports the following services: one-to-one ( unicast ) one-to-all ( broadcast ) one-to-several ( multicast ) IP multicast also supports a many-to-many service. IP Service unicast broadcast multicast 3/28/17 8
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20 bytes ≤ Header Size < 2 4 x 4 bytes = 64 bytes 20 bytes ≤ Total Length < 2 16 bytes = 65536 bytes IP Datagram Format 3/28/17 9 ECN version header length DS total length (in bytes) Identification Fragment offset source IP address destination IP address options (0 to 40 bytes) payload 4 bytes time-to-live (TTL) protocol header checksum bit # 0 15 23 24 8 31 7 16 0 M F D F
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Fields of the IP Header Version (4 bits) : current version is 4, next version will be 6. Header length (4 bits) : length of IP header, in multiples of 4 bytes DS/ECN field (1 byte) This field was previously called “Type-of-Service” (TOS) field. The role of this field has been re- defined, but is “backwards compatible” to TOS interpretation Differentiated Service (DS) (6 bits): Used to specify service level (currently not supported 3/28/17 10
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Fields of the IP Header Identification (16 bits): Unique identification of a datagram from a host. Incremented whenever a datagram is transmitted Flags (3 bits): First bit always set to 0 DF bit (Do not fragment) MF bit (More fragments) Will be explained later Fragmentation 3/28/17 11
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Fields of the IP Header Time To Live (TTL) (1 byte): Specifies longest paths before datagram is dropped Role of TTL field: Ensure that packet is eventually dropped when a routing loop occurs Used as follows: Sender sets the value (e.g., 64) Each router decrements the value by 1 When the value reaches 0, the datagram is dropped 3/28/17 12
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