The Network Layer Forwarding –Internal path to follow Routing –External path to follow Models –Guaranteed delivery with or without bounded delay –In-order packet delivery –Guaranteed minimal bandwidth –Guaranteed maximum jitter

test

Virtual Circuits Connection Oriented Connection state information Phases –VC Setup –Data Transfer –VC Teardown

Datagram Networks Internet Not connection oriented No guarantee of delivery Faster

Routing Address Interface 0 Address Interface 1 Address Interface 2 Address Interface 3 Address Interface 4

Routers

Router Switching

Queueing Packet Scheduling Quality of Service Active Queue Management

Router Configuration Lookup –Helper addresses Forwarding Queueing Other protocols –IPX/SPX (Novell, Microsoft) –Appletalk (Macintosh) –DECnet (card readers)

Routing on the Internet RIP (Routing Internet Protocol) –Lots of traffic (advertisements) –Not very efficient –Basically obsolete OSPF (Open Shortest Path First) –Flooding –Secure –Multiple same cost paths –Multicast and Unicast capable

Router Monitoring Traceroute (tracert) –Simple routing test USU’s Web site for monitoring: What’s UP

IP Network Communication IPv4 Addressing Network Layer (IP, Layer 3) Protocols are described in RFCs (Request for Comments) Available from nis.nsf.net/internet/documents/rfc TCP/IP Addressing –Class A (1-126).xxx.xxx.xxx –Class B ( ).(assigned).xxx.xxx –Class C ( ).(assigned).(assigned).xxx

Internet Addressing Each address is 4, 8 bit, decimal numbers Like Area Code/Exchange/Subscriber is assigned to USU (domain) 172.xxx.xxx.xxx USU nonroutable 7 is assigned to Computer Science 170 is assigned to PC named java4 Every Internet device must have a number Number to name conversion is done by DNS

IP header Version number (4 bits) –Tells router how to interpret datagram Type of Service –Selects delivery speeds vs. accuracy Datagram Length (16 bits) rarely longer than 1500 bytes Identification, Flags and Fragment offset –Reassembly of a fragmented datagram Time to Live –Router hops, control routing loops Protocol (TCP,ICMP, UDP) Header Checksum Source and Destination IP addresses

VersionLengType of SvcTotal Length IdentificationFlags Frag Offset Time to Live ProtocolHeader Checksum IP Header Source Address Destination Address TCP Header then your data...

IP Fragmentation Not all routing systems utilize 1500 byte packets. PPP (dialup) sizes are 576 bytes. Like TCP frames, IP frames need to be reassembled in order even if one packet is lost.

IP Fragmentation

Subnets Class A Class B –USU uses for subnetting buildings Class C Subnet Masks – /16 – /24

Flat vs. Routed Networks Flat network –Enormous party line –Systems move freely around enterprise –Simple and cheap to implement Routed network –Require subnetting –Control packet flow –Systems must readdress as they move

Subnetting

Obtaining a host address Number Assignment –( –Whois Number registration: Manual configuration –Inserting IP numbers for subnet, router, nameserver Dynamic Host Configuration Protocol –Dynamic versus Static IP addressing –Discussed in next weeks presentation

ICMP Ping Router information

Network Address Translation (NAT) Protects internal systems –Makes internal systems invisible Recycles Internet Addresses (IP) Uses nonroutable IP addresses –10.xxx.xxx.xxx –172.xxx.xxx.xxx –192.xxx.xxx.xxx

IP Version 6

Conversion to IPv6 Addressing –3ffe:ffff:0100:f101:0210:a4ff:fee3:9566 –Compatibility: ::ffff:w.x.y.z Dual Stack Tunneling

IPv6 Extended address capabilities Streamlined header Flow labelling No fragmentation or reassembly No header checksum (redundant) No options

Broadcasting and Multicasting Uncontrolled Flooding –Copy of each packet to all neighbors –Can cause broadcast storms Controlled Flooding –Sequence number controlled flooding –Reverse path forwarding Spanning Trees

Multicasting

Types of Multicast Management Protocols Internet Group Management Protocol Distance-Vector Multicast Routing Protocol Protocol-Independent Multicast protocol

Applications of Multicast Online conferencing (mbone) –Video –Sound System Imaging –Symantec Ghost –Powerquest DriveImage

IP Layer The End Remember Homework 2 from the Website