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Section 8: TCP/IP Protocol
Suite and Utilities

CSIS 479R Fall 1999

“Network +”

George D. Hickman, CNI, CNE


Objectives


Identify the components of the TCP/IP
protocol suite as they relate to the OSI
and DoD models


Describe distance vector routing with IP


Describe link state routing with IP


List the protocols that comprise TCP/IP

Objectives (Con’t)


Use Windows TCP/IP utilities


Describe the IPX/SPX Protocol Suite and
the OSI reference model


Describe routing with RIP/SAP


Describe the Protocols used in a
Windows NT Network

TCP/IP


TCP


Transmission Control Protocol


Responsible for establishing
communication between two systems


IP


Internet Protocol


Responsible for the transfer of data

DoD Model


Process/Application


Acts as the User Interface; Provides applications that transfer data
between hosts


Host
-
to
-
Host


Maintains data integrity; sets up reliable end
-
to
-
end communication;
ensures error
-
free delivery (proper sequence, no loss or duplication)


Internet


Routing; Foundation of TCP/IP protocol suite


Network Access


Defines physical interconnection between hosts

TCP/IP Suite and OSI Model


See figure 8
-
2 on page 8
-
6



TCP maps to Transport layer



IP maps to Network layer

Routing IP


IP is the portion of the TCP/IP Suite
that provides addressing and
connectionless services for packet
forwarding; packet switching


IP allows an internetwork to be divided
into logical groups called
autonomous
systems

Autonomous Systems


A group of networks administered by a
single authority


IGPs: Interior gateway protocols route
information within an autonomous
system


EGPs: Exterior gateway protocols (or
Border gateway protocols

BGP)
interconnect autonomous systems

Distance Vector Routing with IP


RIP


Routing Information Protocol


Routers advertise a “metric” of how
many hops they are from a network


Can be advertised higher if needed


Costs of a route are 1
-
16 metrics


A route with a cost of 16 is considered
unreachable

Drawbacks of RIP and
Distance Vector Routing


Convergence


The amount of time it takes all routers to
synchronize their databases when a
change occurs to the network


Slow convergence


Also called the
count
-
to
-
infinity problem

Count
-
to
-
infinity problem


Split Horizon


Destinations are not advertised at all to the
interface from which they were learned


Figure 8
-
6 page 8
-
12


Poison Reverse


All routes learned from a network are
advertised back to the network with a cost of
16


Enabling Poison Reverse reduces
convergence time, but increases RIP traffic

RIP and RIP II


RIP routers broadcast their routes every
30 seconds


RIP II routers add support for:


Authentication


Subnet masks


Next Hop Addresses


Multicast Packets


IP multicast address for RIP II is 224.0.0.9

Link State Routing

OSPF


L. S. routing minimizes size of routing tables


Open Shortest Path First Protocol


Build route tables from packets distributed by
other routers


“Hello packets” contain information about a
routers directly connected interfaces and their
costs.


They establish/maintain neighbor relationships
between routers on same segment

OSPF learning routes


1. Identify neighboring routers (“Hello”)


Announces itself (address and mask) to
other routers


Determines router’s neighbors


Establishes interval that routers send hello’s


Identifies DR (Designated Router)


Router with highest priority


Identifies BDR (Backup Designated Router)


Router with second highest priority

OSPF learning routes (Con’t)


2. Synchronizing link state advertisement
databases


All routers create and synchronize their LS
advertisement databases with the DR and
BDR (after DR and BDR elected, neighbor list
created)


Before synchronization routers communicate
in
two
-
way state


After synchronization, routers enter the

full
neighbor state.
Routers then have

adjacency


Selecting Routes


Link State Advertisement DB is OSPF
router’s view of the internetwork


OSPF algorithm determines path(s) and
adds up the cost(s). Lowest cost wins,
and is added to routing table.


Algorithm rebuilds table when change in
LSDB occurs, after a hold
-
down interval


Maintaining Route Information


Link State Update (LSU) packets are
sent when changes occur or every 30
minutes (default)


DR floods packet to local network


Each router compares LSU to it’s DB.
Resets aging timer. Entry dropped if
age=4 times router dead interval


Router sends ACK to original router

OSPF Terms


Autonomous System (AS)


A group of routers that exchange routing
information using a common routing protocol in a
single administrative unit.


Autonomous System Border Router (ASBR)


A router that exchanges routing information with
routers belonging to other AS. ASBRs distribute
routing info about external destinations

OSPF Terms (Con’t)


Area


Large enterprise
-
area networks are logically
divided into smaller contiguous networks.


Areas act like an AS, so OSPF routers do not
have to maintain LSDB on other areas


Reduces LS Acknowledgements (LSA) sent


Reduces size of DB on each router


Reduces amount of time to recompute routes
following a change to the internetwork

OSPF Terms (Con’t)


Backbone


A logical area to which all other areas are
connected. Address is always 0.0.0.0


Stub area


An area with only one ABR


Transit area


Areas with more than one ABR


See page 8
-
23

OSPF vs. RIP


OSPF is considered superior to RIP


Support for large Internetworks


RIP Metric <= 16; OSPF Metric <= 65535


Variable Length Subnetting


LSA’s include subnet mask information about
networks. Different segments can have
different subnets


Rapid Convergence


No count
-
to
-
infinity problem


Reduced Internetwork Traffic


RIP broadcasts DB every 30 seconds; OSPF
only when changes occur

Protocols in the TCP/IP Suite


Internet Layer Protocols


IP


ICMP


Address resolution Protocols


ARP


RARP


BOOTP

Protocols in the TCP/IP Suite


Host
-
to
-
Host layer Protocols


TCP


UDP


Process/Application layer Protocols


FTP / TFTP


HTTP


SMTP


POP3


SNMP

Internet Layer Protocols


Primary purpose is to route packets
between hosts, often through many
routers


Internet layer performs routing and
packet switching


IP


Provides specifications that allow routing,
fragmentation, and reassembly to occur


Provides connectionless, non
-
guaranteed
delivery of transport layer packets (TPDU)


IP can fragment TPDU into smaller parts
for transmission and reassemble them
later

ICMP


Internet Control Message Protocol


Works with IP to provide internetwork error
and other control info to TCP and other
upper
-
layer protocols


ICMP messages are sent when


A packet cannot reach destination


A packets TTL expires


IP header problem


To notify internetwork of congested/failed links


Etc.

Address Resolution Protocols


ARP/Reverse ARP


Maps 4
-
byte software
-
based IP addresses to
6
-
byte hardware
-
based Data Link addresses


RARP retrieves IP address from hardware
address. Used by diskless workstations


BOOTP


BOOTP servers keep MAC and IP addresses


Newer, more commonly used than RARP

DHCP


Dynamic Host Configuration Protocol


Provides configuration parameters to IP hosts


Automatic allocation


Permanent address assigned to host


Dynamic allocation


Address leased to host for a limited time


Manual allocation


DHCP delivers manually assigned numbers


TCP


Transmission Control Protocol


Transport Protocol


Accepts messages of any length from
UPLs,


Provides full
-
duplex, acknowledged,
connection
-
oriented, flow controlled,
transport to a TCP peer

UDP


User Datagram Protocol


Transport Protocol


Not connection oriented


No acknowledgements


UDP just accepts and transports datagrams
from a ULP


UDP has lower overhead, so is faster than
TCP

FTP


File Transfer Protocol


Move files between hosts


Allows login, directory inspection, file
manipulation, command execution


Uses virtual circuits to establish a reliable
path between hosts


TFTP Trivial FTP


No password, directory listings. Good for
downloads


Runs on UDP

not as reliable

HTTP


Hyper Text Transfer Protocol


Language of the WWW portion of
Internet


Establishes connection with a server
and sends a request


URL: Uniform Resource Locators

SMTP


Simple Mail Transfer Protocol


A standard for exchanging mail
between workstations


Relies primarily on TCP to route
messages between network hosts


Does not provide user interface

POP3


Post Office Protocol 3


Standard Mail server


Provides message store


Users connect and retrieve all pending
messages and attachements at once


Uses SMTP messaging protocol

SNMP


Simple Network Management Protocol


Allows management of a network from a
“SNMP manager” workstation


Each host has a Management Information Base
(MIB) that holds data about itself


When a threshhold is reached, a “trap”
message is sent to the management console


Example: router sends SNMP trap when an
interface goes down

Windows TCP/IP Utilities


ARP.EXE


Diagnostic utility for ethernet TCP/IP


ARP stores a cache of host IP addresses and
physical addresses


FTP .EXE


IPCONFIG.EXE (WinNT) WINIPCFG (Win9x)


Shows IP settings on local machine



Windows TCP/IP Utilities


NBTSTAT.EXE


Displays statistics and existing TCP/IP
connections using NetBIOS over TCP/IP


NETSTAT.EXE


Identifies status of TCP/IP connections and
provides statistics on them

Windows TCP/IP Utilities


PING.EXE


Packet InterNet Groper


Determine if a host is available; quality of the
connection


TELNET.EXE


Remote Terminal Connection


TRACERT.EXE


Traces a connection route to a host and its hops

IPX/SPX


Novell’s protocol suite based on Xerox
Network System (XNS) protocol suite


IPX gets packets through internetwork


SPX offers connection
-
oriented
guaranteed delivery of packets.

IPX Addressing


Network Address


8 digit hexadecimal number assigned to wire


Internal Network Address


8 digit hexadecimal number assigned to server


MAC or Node Address


12 digit hexadecimal number assigned to NIC


Socket number


Determines destination within a device (RIP,
SPX)

RIP/SAP Routing


RIP is IPX distance vector


Uses hop and tick counts to determine cost


SAP is Service Advertising Protocol


Advertise services of all known servers on the
network


Periodic SAP Information broadcasts (60 seconds)


SAP Service Inquiries


SAP Service Responses


SAP traffic needs to be filtered to avoid
bandwidth problems

Windows NT Protocols


NetBEUI


NetBIOS Extended User Interface


Not Routable


NWLink IPX/SPX Compatible Transport


NDIS
-
compliant version of Novell IPX/SPX


Others


Apple Talk


DLC Protocol


IBM Mainframes and AS/400


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