terminology and basic structures for lab 1 ©2012 prof. josé maría foces morán

©2012 Prof. José María Foces Morán

Basics of Computer Network technology

Terminology and basic structures for lab 1


Networks by geographic dispersion

LAN: Local Area Network. 10 to 1000 m University campus.

MAN: Metropolitan Area Network. 1 a 10 Km A city

WAN: Wide Area Network. Más de 10 Km A province, a country


Physical transmission media Medios físicos de transmisión Twisted pair cables

Inexpensive, entre 10 y 1000 Mbps (Mega bits per second)▪ STP (Shielded Twisted Pair)▪ UTP (Unshielded)▪ Cat 3 (30 Mbps)▪ Cat 5 (100 Mbps)▪ Cat 6 (1 Gbps)


Physical media

Coaxial cables Single, inner

conductor▪ Thick (2Km max

length, 20Mbps max. frequency)

▪ Thin (RG-58/U) Noise sensitive T Connector, BNC

type Termination

resistors


Physical media

Fiber optics Transmission of light

ray in a light-transmitting material

Immune to electromagnetic radiation

In the order of Gbps, depending on grade

Monomode Multimode Laser and LED drivers


Basic equipment

Network Interface Card (NIC) Provides access to a LAN By using a cable or optical

fibers Connected to a computer by

using a PCI-X bus Associated to a unique level-

2 address ▪ MAC (Media Access Control

address) o LLA (Link Level Address)

▪ A 48-bit number assigned by the IEEE


Basic equipment

Concentrator (HUB) Creates a unique

collision and broadcast domain

All nodes share the physical medium

As though it were a single cable shared by all nodes

Virtually not used today Operates at the

physical level (OSI level 1)


Basic equipment

Conmutador (SWITCH) Supports several

“communications” at the same time

Several two-node pairs may opt to the full bandwidth

Most common case today These devices learn the

MAC addresses of the nodes as they initiate communication

Operates at the level 2


Basic equipment

Switch, basic functions: MAC Address learning▪ Keeps a table that

associates port number and MAC: Content Addressable Memory

Filtering Forwarding


Interconnection of switches

A switched LAN with two segments

Uplink: A special port that

aggregates traffic Higher bandwidth

than the other ports▪ 1000-BASE-T over

CAT6 twisted-pair cables

▪ Gigabit Ethernet over MM (Multi Mode) fiber optics


Interconnection of LANs

IP Router: Works at the

internetwork level (OSI no. 3)

PDU: Forwards IP packets Used to create

internetworks Functions

IP forwarding DHCP server NAT/PAT Firewall


Introduction to IPv4 addressing Each IP address is 32

bits in length Four bytes a.b.c.d:▪ Decimal 0-255▪ Hex 0x0 – 0xff

Hierarchical, two parts:▪ Network number▪ Example/24: 24 bits

▪ Node number:▪ 32 – 24 = 8

Two special cases▪ Broadcast: 255.255.255.255▪ Loopback: 127.0.0.1


Introduction to IPv4 addressing▪ IP address types:▪ Classful

A, B y C, etc.▪ CLASSLESS

CIDR/VLSM▪ Private ranges

For use within an organization

▪ Public For addressing in the

general Internet

▪ We will explain how to calculate the network number, etc


IP and MAC addresses

▪ Each node has two addresses:▪ MAC (Its network interface

card, NIC)▪ IP address

▪ How are these addresses related?▪ Address Resolution Protocol▪ ARP keeps the relation

between the two up-to-date

▪ Play with the arp –a command in your system


Relevant protocols to these labs


Practical work

Discover the network configuration of your system Operating system name IP address This system’s NICs MAC addresses The network mask Our access router (Default router) Arp table Name server


Node name and operating system name and version

Boot your system to Linux Login into your system:

The instructor will provide user/passwd Request a shell (A terminal or command

processor) Which system is this? Type the following

command after the shell prompt: $ uname –a

Linux llull 2.6.26-2-686 #1 SMP Thu Aug 19 03:44:10 UTC 2010 i686 GNU/Linux

The name of this node $ hostnamellull


On-line help

The man command offers you the manual page of the indicated command: $ man uname

Other Unix useful commands: $ ls –l $ pwd $ cat /etc/services $ more /etc/hosts $ exit $ netstat –a | grep SOCK | more


The network interface card (NIC) Your system may have more than one installed $ man ifconfig $ ifconfig

eth0 Link encap:Ethernet HWaddr 90:e6:ba:cd:96:d9 inet addr:192.168.99.202 Bcast:192.168.99.255 Mask:255.255.255.0 inet6 addr: fe80::92e6:baff:fecd:96d9/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:498 errors:0 dropped:0 overruns:0 frame:0 TX packets:418 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:47523 (46.4 KiB) TX bytes:54582 (53.3 KiB) Interrupt:220 Base address:0x2000

What do the different fields mean? Consult the manual page, lookup the following fields: Link encap: Ethernet Hwaddr: inet addr: Bcast: Mask:


The state of this machine’s network module

$ netstat –aActive Internet connections (servers and established)Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 *:nfs *:* LISTEN tcp 0 0 *:afpovertcp *:* LISTEN tcp 0 0 *:swat *:* LISTEN tcp 0 0 *:36938 *:* LISTEN tcp 0 0 *:sunrpc *:* LISTEN tcp 0 0 *:56501 *:* LISTEN tcp 0 0 localhost:ipp *:* LISTEN tcp 0 0 localhost:smtp *:* LISTEN tcp 0 0 *:59514 *:* LISTEN tcp 0 0 *:26 *:* LISTEN tcp 0 0 llull.local:26 10.20.48.88:49699 ESTABLISHEDtcp6 0 0 [::]:netbios-ssn [::]:* LISTEN tcp6 0 0 [::]:www [::]:* LISTEN


State of the Address Resolution Protocol (ARP) module

Ejecutad este comando antes de continuar:

$ PATH=$PATH:/usr/sbin:/sbin

chema@llull:~$ arp -vAddress HWtype HWaddress Flags Mask IfaceTime-Capsule-Augustus-A ether 00:24:36:a2:e4:50 C eth0Entries: 1 Skipped: 0 Found: 1

chema@llull:~$ arp -vnAddress HWtype HWaddress Flags Mask Iface192.168.99.1 ether 00:24:36:a2:e4:50 C eth0Entries: 1 Skipped: 0 Found: 1


Ping: test IP connectivity$ man pingPacket Internet Groper test IP connectivity (OSI

level 3)

chema@llull:~$ ping paloalto.unileon.esPING paloalto.unileon.es (193.146.96.163) 56(84) bytes of data.64 bytes from paloalto.unileon.es (193.146.96.163): icmp_seq=1 ttl=255 time=0.266 ms64 bytes from paloalto.unileon.es (193.146.96.163): icmp_seq=2 ttl=255 time=0.121 ms


Traceroute: Calculate the route to a destination host

llull:/home/chema# traceroute paloalto.unileon.estraceroute to paloalto.unileon.es (193.146.96.163), 30 hops max, 40 byte

packets

1 paloalto.unileon.es (193.146.96.163) 0.400 ms 0.501 ms 0.604 ms

llull:/home/chema# traceroute www.cisco.comtraceroute to www.cisco.com (88.221.8.170), 30 hops max, 40 byte packets

1 Time-Capsule-Augustus-Aurelius.local (192.168.99.1) 0.460 ms 0.542 ms 0.664 ms

2 n096129.unileon.es (193.146.96.129) 3.336 ms 3.366 ms 3.393 ms 3 n111003.unileon.es (193.146.111.3) 3.428 ms 3.439 ms 3.488 ms

4 GE3-0-3-50.EB-Valladolid0.red.rediris.es (130.206.201.45) 4.024 ms 4.159 ms 4.408 ms

5 CAL.SO6-1-1.EB-IRIS4.red.rediris.es (130.206.250.81) 13.692 ms 13.947 ms 14.123 ms


Which IP routes does this node know of?

$ route –a

chema@llull:~$ route -vKernel IP routing tableDestination Gateway Genmask Flags Metric Ref Use Iface192.168.99.0 * 255.255.255.0 U 0 0 0 eth0default Time-Capsule-Au 0.0.0.0 UG 0 0 0 eth0

chema@llull:~$ route -vnKernel IP routing tableDestination Gateway Genmask Flags Metric Ref Use Iface192.168.99.0 0.0.0.0 255.255.255.0 U 0 0 0 eth00.0.0.0 192.168.99.1 0.0.0.0 UG 0 0 0 eth0chema@llull:~$


Network configuration data in UNIX

What’s the purpose of the following files?

(See $ man hosts for example) /etc/hosts /etc/services /etc/networks


Lab exercises

Determine the following network configuration parameters of your system:① Your network access NIC’s MAC address② Your local net’s default router ip address③ Your NIC’s network mask④ Which type if your IP address, A, B or C?▪ Determine the first high order bits of the IP address▪ Class A: MSb is a 0▪ Bit 31 is a 1 and bit 30 is a 0▪ Bit 31 is a 1, bit 30 is a 1 and bit 29 is a 0


Lab exercises

Use your browser to access www.unileon.es, then, discover how this new connection appears in the output of the following command: $ netstat –a | more

Which local and remote ports make up this connection?

http://www.unileon.es/


CN computing infrastructure Required/recommended computing

infrastructure for completing the CN Labs A standard Windows-XP or Windows-7

installation▪ Test basic IP configuration commands▪ Install OpNet Simulator, student version

Ubuntu Linux▪ Basic IP configuration, routing, DNS client▪ Java Compiler and Runtime + IDE▪ Wireshark Network Analyzer

terminology and basic structures for lab 1 ©2012 prof. josé maría foces morán

Documents