Networking Concepts Lesson 06 - Protocols - Eric Vanderburg

Networking Concepts – Eric Vanderburg ©2005

Chapter 6

Protocols


Communication

Send small piecesLessen impact from errorsMinimize bandwidth usageSupport maximum sending requirements


Packets

HeaderSource/DestinationSequence numberPriority

Data (Payload) – 50b-16kbTrailer

Integrity checking infoPadding


Packet Types

Unicast (one)Point-to-point

Anycast / Broadcast (all)Destination address is broadcast address

Multicast (group)Point-to-multipoint communicationDestination address is multicast addressAll computers with multicast address get

this message


Protocols

Rules of communication Protocol Suite – collection of protocols to operate at multiple

layers Routable protocols – can operate at layer 3.

TCP/IP IPX/SPX DECNet DDP (Datagram Delivery Protocol) – AppleTalk XNS - Xerox

Non-routable protocols NetBEUI DLC (Digital Loop Carrier) – for HP printers & IBM

mainframes LAT (Local Area Transport) DEC


Connection

Connection Oriented (Statefull)More reliableSlower (control & check data)TCP, FTP

Connectionless (Stateless)Less reliableFasterUDP, TFTP, PPPDatagrams


OSI and Protocols

ApplicationApplication Layer (7)Presentation Layer (6)Session Layer (5)

TransportTransport Layer (4)

NetworkNetwork Layer (3)Datalink Layer (2)Physical Layer (1)


Application Protocols

Application to Application services

SMTP (Simple Mail Transport Protocol) FTP (File Transfer Protocol) SNMP (Simple Network Management

Protocol) NCP (NetWare Core Protocol) – client and

redirector AFP (AppleTalk File Protocol) – remote file

management


Transport Protocols

Handle delivery between nodes

TCP (Transmission Control Protocol)SPX (Sequenced Packet Exchange)NetBIOS (Network Basic Input Output

System)


Network Protocols

Provides “Link Services” that address, route, and check for errors

IPv6 (Internet Protocol version 6) IPv4 (Internet Protocol version 4) IPX (Internetwork Packet Exchange) NWLink NetBEUI (NetBIOS Extended User Interface)


Protocol Suites

TCP/IP IPX/SPX NetBIOS / NetBEUI AppleTalk DLC (Digital Loop Carrier) XNS (Xerox Network Systems) DECNet (Digital Equipment Corporation

Network) X.25 – WANS and connects terminals to

mainframes


XNS

IDP (Internet Datagram Protocol) – Layer 2 RIP (Routing Information Protocol) – Layer 3 PEP (Packet Exchange Protocol) – Layer 4 SPP (Sequenced Packet Protocol)


DECNet

RP (Routing Protocol) MOP (Maintenance Operation Protocol) - uploading

and downloading system software, remote testing and problem diagnosis

NSP (Network Service Protocol) - flow control SCP (Session Control Protocol) DAP (Data Access Protocol) – remote file access CTERM (Command Terminal) LAT (Local Area Transport) STP (Spanning Tree Protocol) NIC bridging LAVC (Local Area VAX Cluster)


DECNet


TCP/IP

IP – Connectionless, provides routing and logical addressing

ICMP (Internet Control Message Protocol) – sends error messages, flow control instructions, confirmations Ping command

ARP (Address Resolution Protocol) – associates an IP with a MAC

TCP – fragmentation, reassembly, connection setup & maintenance, sequencing


TCP/IP

UDP – connectionless version of TCP, used by NFS (Network File System) & DNS

FTP (File Transfer Protocol) – upload, download, delete, move files

Telnet – connect and control systems, routers, & switches

SMTP – operates at 3 upper layers, mail


TCP/IP

RIP (Routing Information Protocol) Distance vector – each router sends its routing

table to its neighbors, sends link costs also RIPv2 has better performance than RIP Use on smaller networks

OSPF (Open Shortest Path First) Link-state routing – each router has partial map of

network. LSA (Link State Advertisement) is sent through the network when a link goes up or down.

Better on larger networks Requires more computations on each router


IP Addresses

Class A - 0nnnnnnn hhhhhhhh hhhhhhhh hhhhhhhh First bit 0; 7 network bits; 24 host bits Initial byte: 0 - 127 126 Class As exist (0 and 127 are reserved) 16,777,214 hosts

Class B - 10nnnnnn nnnnnnnn hhhhhhhh hhhhhhhh First two bits 10; 14 network bits; 16 host bits Initial byte: 128 - 191 16,384 Class Bs exist 65,532 hosts

Class C - 110nnnnn nnnnnnnn nnnnnnnn hhhhhhhh First three bits 110; 21 network bits; 8 host bits Initial byte: 192 - 223 2,097,152 Class Cs exist 254 hosts


IP Addresses

Class D - 1110mmmm mmmmmmmm mmmmmmmm mmmmmmmm First four bits 1110; 28 multicast address bits Initial byte: 224 - 239 Class Ds are multicast addresses

Class E - 1111rrrr rrrrrrrr rrrrrrrr rrrrrrrr First four bits 1111; 28 reserved address bits Initial byte: 240 - 255 Reserved for experimental use


IP Addresses

Register an IP IANA (Internet Assigned Numbers Authority)

Private IP Address Ranges Class "A" or 24Bit

10.0.0.0 - 10.255.255.255/8 Subnet Mask: 255.0.0.0

Class "B" or 20 Bit 172.16.0.0 - 172.31.255.255/12 or /16 255.240.0.0 or 255.255.0.0

Class "C" or 16 Bit 192.168.0.0 - 192.168.255.255/16 or /24 255.255.0.0 or 255.255.255.0

Requires NAT (Network Address Translation) to access the Internet Auto-configured Addresses 169.254..

APIPA (Automatic Private IP Addressing) Loopback Address 127… (localhost)


CIDR

Classless Inter-Domain RoutingWeakens boundaries between address

spaces. Specified by number of bits /24 denoting

the bits in the network address


Subnetting

Subnetting – dividing an IP address range into smaller networks (subnets)

Subnet Mask – address that shows which subnet a host belongs toNetwork bits are 1’sHost bits are 0’s

Each network needs an address for the network address and broadcast address (all 1’s and all 0’s)


Finding Host & Network Address

Convert from Decimal to BinaryCompare Subnet Mask to IP in BinaryConvert new Binary number to Decimal


Subnetting

Determine needed hosts and networksAdd 2 to needed networksFind power of 2 that is larger than the #Hosts is number of bits left over used in

power of 2 and subtract 2.


Supernetting

Combining multiple IP addresses into a larger network to support more hosts than could be achieved separately (synergy)

Find how many binary digits it takes to account for the number of IP’s you have If the number of addresses is not equal to

the binary digit calc, use lower number and some IPs will not be supernetted.


NAT/PAT

NAT Lets an organization use Private IP’s Increases security Translates internal to external IP

PAT (Port Address Translation) Maps internal IP’s to external IP and port number Used by most NATs

Linux VPN Masquerade – essentially NAT services for Linux


DHCP

Dynamic Host Configuration ProtocolGives IP addresses to clients as neededScope, Reservations, & ExclusionsLease Length

After 50% expired, try to renewAuto-configured address used if no

assigned IP, good if DHCP goes down or if no server is available


MADCAP

MADCAP (Multicast Address Dynamic Client Allocation Protocol)

Gives multicast addresses to clientsMulticast scope (class D)Scope, Reservations, & ExclusionsLease Length


IPv6

Aka: IPNG (Internet Protocol Next Generation) July 25, 1994 in RFC 1752, Core Protocols in 1998 128 bit address space instead of IPv4’s 32 bit address space 340,282,366,920,938,463,463,374,607,431,768,211,456

maximum possible addresses Specified in Hex (4 Hex digits and :) in 8 sets Leading 0 is omitted First Set – Public topology (ISP, backbone), 48bits Second Set – Site topology (business), 16bits Third Set – Interface ID, 64bits Security information, sender/receiver verification, & encryption in

each packet Backward compatible


DNS (Domain Name Service)


DNS

Vendor Products Windows DNS Server

Active Directory Integrated DDNS (Dynamic Domain Name Service)

BIND (Berkley Internet Name Domain) Server Types

Primary Server Secondary Server Caching Only Server Forwarding Only Server (Slave)

FQDN (Fully Qualified Domain Name) Zone – Specific DNS namespace, a server or servers can be

responsible for a zone Reverse Lookup Zone – search for FQDN from IP


DNS RRs (Resource Record)

SOA (Start of Authority) – First record, which server manages this zone@ IN SOA source_host email serial#

NS (Name Server) – Lists name servers in a domain. Allows other NS’s to look up records in your zone. Domain @ IN NS nameserver_host

A (Host) – Host to IPhostname IN A IP_Address

PTR (Pointer) – FQDN to IPowner ttl class PTR FQDN

CNAME – provides alternate hostnames (www)alias IN CNAME hostname

MX (Mail Exchange)domain IN MX priority mailserver_host


Example DNS file


Recursive, Iterative, & Caching


NetBIOS, NetBEUI

First used in IBM’s PC-Net & later MS-Net Each computer has 15 character name and

one character for a service code NetBEUI created for OS/2 and LAN Manager

NetBIOS is for upper layers NetBEUI for layers 2-4

Used in early Windows systems as the default protocol


NetBIOS Service Codes

Common NetBIOS Names Service That Registers the Name

<computer name>[00h] Workstation (your NetBIOS Redirector)

<computer name>[03h] Messenger(listens for messages sent to your computer)

<computer name>[20h] Server (Shares your resources to the network)

<user name>[03h] Messenger (listens for messages sent to your logon ID)

<domain name>[1Dh] Master Browser

<domain name>[1Bh] Domain Master Browser

Name Cache (nbtstat –c)


NBT

NBT (NetBIOS over TCP/IP)

Allows NetBIOS names to be translated to IP addresses so that they can be routed across the network

Check the box to enable NBT


NetBIOS Node Types

B-Node (Broadcast Node) Broadcast mode uses broadcasts only. NetBIOS Name Cache Broadcast a NetBIOS Name Query Checking the LMHOSTS file Checking a HOSTS file Checking with a DNS server

P-Node(Peer-to-Peer Node) NetBIOS Name Cache Asking a NetBIOS Name Server HOSTS file DNS


NetBIOS Node Types

M-Node(Mixed Node) NetBIOS Name Cache Broadcast a NetBIOS Name Query Checking the LMHOSTS file Asking a NetBIOS Name Server Checking a HOSTS file Checking with a DNS server

H-Node(Hybrid Node) NetBIOS Name Cache Asking a NetBIOS Name Server Broadcast a NetBIOS Name Query Checking the LMHOSTS file Checking a HOSTS file Checking with a DNS server


Nbtstat switches

-n Lists the NetBIOS name registered by the client

-c Displays NetBIOS name cache.-R Manually reloads the NetBIOS name

cache using entries in the LMHOSTS file with a #PRE parameter.


Hosts file

Maps NetBIOS names to IP AddressesWorks on Windows and UNIXNT Location: %winroot%\system32\drivers\

etc Unix Location:- /etc/hosts File Name- HOSTS # is used for comments


Example Hosts file

127.0.0.1 localhost 13.41.85.1 router 13.91.45.121 server1 13.91.45.122 server214.33.121.121 mcsunix # Solaris 10 machine 14.33.121.122 mail # Server 2003 Mail Server 189.11.121.11 sunshinemtn.com web # Web server


LMHosts file

Maps NetBIOS names to IP Addresses Location:- %winroot%\system32\drivers\etc File Name- LMHOSTS

#PRE - A #PRE tag tells the computer to pre-load the entry to the name cache during initialization or after the NBTSTAT -R command has been issued at the command prompt. Entries of #PRE are static in the cache.

#DOM:[domain_name] - Indicates the computer is a domain controller. #NOFNR - Avoids using NetBIOS name queries on older LAN manager

for UNIX environments. #INCLUDE - Directs the system to the location of the central LMHOSTS

file #BEGIN_ALTERNATE - Used in conjunction with the #INCLUDE file .

This entry marks the begining of entries that are alternative locations for the central LMHOST file. If the first entry is unavailable.

#END ALTERNATE - End of alternative locations statement. #MH - Multihomed computers that have more than one entry


Example File

141.8.2.1 WKS-1 141.8.2.2 WKS-2 #PRE 141.8.2.3 PDC-1 #PRE 156.34.2.9 BDC-1 #PRE 141.8.2.10 Gateway-1 #MH 156.34.2.4 Gateway-1 #MH 156.34.2.7 Server-1 #PRE #INCLUDE \\PDC-1\Scripts\lmhosts #BEGIN_ALTERNATE #INCLUDE\\SERVER-1\Scripts\lmhosts #END_ALTERNATE


SMB

SMB (Server Message Block)Sends file listsStarts connection for LAN ManagerLinks Redirector and Server softwarePresentation layer


IPX/SPX

Used on older Netware networksRequires all computers to use the same

frame typeHas network address for communication

between computers


NetWare

Older versions require IPX/SPXNCP (NetWare Core Protocol) - file &

print services for NetWare (similar to Microsoft’s SMB)

LIP (Large Internet Protocol) - negotiates the largest packet size that can be used


AppleTalk

RTMP (Routing Table Maintenance Protocol)

AURP (AppleTalk Update-Based Routing)

ADSP (Appletalk Data Stream Protocol)ZIP (Zone Information Protocol)AFP (AppleTalk Filing Protocol)


AppleTalk


Channel Access Methods

*Done at Layer 2 MAC sublayer Contention

CSMA/CD – check to see if anyone is using the line. If so, wait random interval and try again. (Ethernet)

CSMA/CA – Send packet to tell other computers you are going to send data. (reduces speed)

AppleTalk Wireless

Switching – Data sent to same MAC at same time. Some computers can be given higher priority (server)

Token Passing Demand Priority – each asks intelligent hub for permission to

send data (raise hand) Polling – allows priority, asks if there is data to send, same

limitations and advantages of token passing (IBM SNA networks)

Technology

Networking Concepts Lesson 06 - Protocols - Eric Vanderburg