Network – internet – part2  Address at diff. layers  Headers at diff. layers  Equipment at diff. layers

Internet Layers - revision  The Layers:

Comparison of Layers  The TCP/IP layers compared to OSI layers

Addresses at diff. layers  Each layer have its own address

Application Addresses  Port numbers  A number between (16 bit) ( reserved)  E.G.  Web = 80  MAIL = 25  FTP = 21

Transport Addresses  Protocol numbers  A number between (8 bit)  E.G.  TCP = 6  UDP = 17  ICMP = 1

Network Addresses  IP-addresses (version 4)  A number between 1- 4billion (32 bit)  Normally shown in dot-notation i.e. each byte shown in distinct number:  An IP-address consist of a network part and a host part e.g. the address consist of the network part and a host part  A submask are used to parted an IP-address into a network and a host part e.g

Link Addresses  Many network are used so many types of address exist.  Often a LAN is used  Where LAN is used the Address is a MAC- address  A MAC-address is 48 bits long and totally unique impress into the network card  An example: 00-0D-56-3C-7C-B1

Headers at diff. layers  Application Headers  Differentiate from application to application  E.g.  Web (HTTP) (ASCII): “GET /laerer.rhs.dk/peterl/index.htm HTTP/1.1”  Network Management (SNMP) (An Header) …. (this is the encoding of an SNMP-header)

Headers at diff. layers  Transport Headers (UDP)

Headers at diff. layers  Transport Headers (TCP)

Headers at diff. layers  Network Headers (IP)

Headers at diff. layers  Link Headers (Ethernet - LAN)

Equipment - overview  Repeaters  Hubs  Bridges  Switches (layer 2)  Routers  Switches (layer 3)  Probes

Equipment – Layer 1  Repeaters  For Ethernet-cable only  Take the signal and amplified it  i.e. with a repeater it is possible to have the cable 370 m. instead of 185 m.  Hubs  Works like a repeater But in a star-topology  Each PC/device have its own cable into the Hub  Normally RJ-45 connector, with a speed up to 100Mbps

Equipment – Layer 2  Bridges  Divide the LAN into segments (i.e. different broadcast domain)  Uses MAC addresses to decide to forward the frame or not.  An equipment with 2 or a few ports.  Switch (layer2)  Works like a bridge But in a star-topology i.e. many ports  Build in hardware, so the internal speed a high  Possible to build up a virtual LAN i.e. some port are connected but not all.

Equipment – Layer 3  Routers  The real workers in the internet – find paths to IP- packets  Uses IP addresses to decide a route.  For decision are routing tables build up.  Possible to use different kind of network (ATM,LAN,ADSL)  Switch (layer3)  Works like a router can have many ports  Build in hardware and have therefore a high speed.

Equipment – Layer 1-3  Probes  Equipment to find error or performance problems  Gives an analysis of the traffic in the network  Also called traffic-analyser or protocol- analyser

That’s all folks