Networking Concepts Lesson 06 - Protocols - Eric Vanderburg

Chapter 6
Protocols

Networking Concepts – Eric Vanderburg ©2005

Communication
 Send

small pieces

 Lessen

impact from errors
 Minimize bandwidth usage
 Support maximum sending requirements

Networking Concepts – Eric
Vanderburg ©2005

Packets
 Header
 Source/Destination
 Sequence

number

 Priority

 Data

(Payload) – 50b-16kb
 Trailer
 Integrity

checking info

 Padding
Vanderburg ©2005

Packet Types
 Unicast

(one)

 Point-to-point

 Anycast

/ Broadcast (all)

 Destination

 Multicast

address is broadcast address

(group)

 Point-to-multipoint

communication
 Destination address is multicast address
 All computers with multicast address get
this message
Vanderburg ©2005

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
Vanderburg ©2005

Connection
 Connection

Oriented (Statefull)

 More

reliable
 Slower (control & check data)
 TCP, FTP
 Connectionless

(Stateless)

 Less

reliable
 Faster
 UDP, TFTP, PPP
 Datagrams
Vanderburg ©2005

OSI and Protocols
 Application
 Application

Layer (7)
 Presentation Layer (6)
 Session Layer (5)
 Transport
 Transport

Layer (4)

 Network
 Network

Layer (3)
 Datalink Layer (2)
 Physical Layer (1)
Vanderburg ©2005

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
Vanderburg ©2005

Transport Protocols
 Handle

delivery between nodes

 TCP

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

Vanderburg ©2005

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)
Vanderburg ©2005

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
Vanderburg ©2005

XNS





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

Vanderburg ©2005

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)
Vanderburg ©2005

DECNet

Vanderburg ©2005

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
Vanderburg ©2005

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
Vanderburg ©2005

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


Vanderburg ©2005

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
 16,384 Class Bs exist
 65,532 hosts
Class C - 110nnnnn nnnnnnnn nnnnnnnn hhhhhhhh
 First three bits 110; 21 network bits; 8 host bits
 2,097,152 Class Cs exist
 254 hosts
Vanderburg ©2005

IP Addresses




Class D - 1110mmmm mmmmmmmm mmmmmmmm
mmmmmmmm
 First four bits 1110; 28 multicast address bits
 Class Ds are multicast addresses
Class E - 1111rrrr rrrrrrrr rrrrrrrr rrrrrrrr
 First four bits 1111; 28 reserved address bits
 Reserved for experimental use

Vanderburg ©2005

IP Addresses


Register an IP




IANA (Internet Assigned Numbers Authority)

Private IP Address Ranges


Class "A" or 24Bit





Class "B" or 20 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..




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




10.0.0.0 - 10.255.255.255/8
Subnet Mask: 255.0.0.0

APIPA (Automatic Private IP Addressing)

Loopback Address 127… (localhost)
Vanderburg ©2005

CIDR
 Classless

Inter-Domain Routing
 Weakens boundaries between address
spaces.
 Specified by number of bits /24 denoting
the bits in the network address

Vanderburg ©2005

Subnetting
 Subnetting

– dividing an IP address
range into smaller networks (subnets)
 Subnet Mask – address that shows
which subnet a host belongs to
 Network

bits are 1’s
 Host bits are 0’s
 Each

network needs an address for the
network address and broadcast address
(all 1’s and all 0’s)
Vanderburg ©2005

Finding Host & Network Address
 Convert

from Decimal to Binary
 Compare Subnet Mask to IP in Binary
 Convert new Binary number to Decimal

Vanderburg ©2005

Subnetting
 Determine

needed hosts and networks
 Add 2 to needed networks
 Find power of 2 that is larger than the #
 Hosts is number of bits left over used in
power of 2 and subtract 2.

Vanderburg ©2005

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.
Vanderburg ©2005

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
Vanderburg ©2005

DHCP
 Dynamic

Host Configuration Protocol
 Gives IP addresses to clients as needed
 Scope, Reservations, & Exclusions
 Lease Length
 After

50% expired, try to renew

 Auto-configured

address used if no
assigned IP, good if DHCP goes down
or if no server is available
Vanderburg ©2005

MADCAP
 MADCAP

(Multicast Address Dynamic
Client Allocation Protocol)
 Gives multicast addresses to clients
 Multicast scope (class D)
 Scope, Reservations, & Exclusions
 Lease Length

Vanderburg ©2005

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

Vanderburg ©2005

DNS (Domain Name Service)

Vanderburg ©2005

DNS


Vendor Products


Windows DNS Server














BIND (Berkley Internet Name Domain)

Server Types




Active Directory Integrated
DDNS (Dynamic Domain Name Service)

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

Vanderburg ©2005

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 IP
hostname IN A IP_Address



PTR (Pointer) – FQDN to IP
owner ttl class PTR FQDN



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



MX (Mail Exchange)

domain IN MX priority mailserver_host

Vanderburg ©2005

Example DNS file

Vanderburg ©2005

Recursive, Iterative, & Caching

Vanderburg ©2005

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

Vanderburg ©2005

NetBIOS Service Codes
Common NetBIOS Names

Service That Registers the Name

<computer name>[00h]

Workstation (your NetBIOS Redirector)


Messenger(listens for messages sent to
your computer)


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)

Vanderburg ©2005

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

Vanderburg ©2005

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
Vanderburg ©2005

NetBIOS Node Types
M-Node(Mixed Node)









NetBIOS Name Cache

H-Node(Hybrid Node)









NetBIOS Name Cache
Vanderburg ©2005

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.

Vanderburg ©2005

Hosts file
Maps

NetBIOS names to IP
Addresses
 Works

on Windows and UNIX
 NT Location: %winroot
%system32driversetc
 Unix Location:- /etc/hosts
 File Name- HOSTS
 # is used for comments
Vanderburg ©2005

Example Hosts file
127.0.0.1 localhost
13.41.85.1 router
13.91.45.121 server1
13.91.45.122 server2
14.33.121.121 mcsunix # Solaris 10 machine
14.33.121.122 mail # Server 2003 Mail Server
189.11.121.11 sunshinemtn.com web # Web server

Vanderburg ©2005

LMHosts file


Maps NetBIOS names to IP Addresses













Location:- %winroot%system32driversetc
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

Vanderburg ©2005

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-1Scriptslmhosts #BEGIN_ALTERNATE #INCLUDE
SERVER-1Scriptslmhosts #END_ALTERNATE

Vanderburg ©2005

SMB
 SMB

(Server Message Block)

 Sends

file lists
 Starts connection for LAN Manager
 Links Redirector and Server software
 Presentation layer

Vanderburg ©2005

IPX/SPX
 Used

on older Netware networks
 Requires all computers to use the same
frame type
 Has network address for communication
between computers

Vanderburg ©2005

NetWare
 Older

versions require IPX/SPX
 NCP (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

Vanderburg ©2005

AppleTalk
 RTMP

(Routing Table Maintenance
Protocol)
 AURP (AppleTalk Update-Based
Routing)
 ADSP (Appletalk Data Stream Protocol)
 ZIP (Zone Information Protocol)
 AFP (AppleTalk Filing Protocol)
Vanderburg ©2005

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)

Vanderburg ©2005

Networking Concepts Lesson 06 - Protocols - Eric Vanderburg

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