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CIS 471 (1)
Dr.Mike (1)

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Department
CIS - Computer Information Systems
Course Code
CIS 471
Professor
Dr.Mike

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Straight-through - Connect PC to hub or switch (router to switch or
hub)
Crossover - Connect hub to hub/ switch to switch/PC to PC
Rolled - Console connection for PC to router
Half Duplex Ethernet shares a collision
domain resulting in lower throughput
than Full Duplex Ethernet which
requires a point-to-point link between
two compatible nodes
Causes of LAN congestion - Broadcast
storms, too many hosts with a broadcast
domain, multicasting, low bandwidth,
bottlenecks
Collision domain - Switches/bridges
breakup collision domains, hubs extend
them
Broadcast domains - Routers and
VLANs breakup broadcast domains
Cisco 3-Layer Hierarchical Model
Core - Backbone, common to all users, needs to be as fast as possible
and fault tolerant, avoid ACL, VLAN trunking and packet filtering here.
Distribution - Routing - provides access control policies, filtering, WAN
access and VLAN trunking
Access - Switching - User and workgroup access, segmentation
OSI Model vs. TCP/IP Model
Troubleshooting Steps
1. Ping 127.0.0.1
(Loopback)
2. Ping default gateway
3. Ping remote device
Windows DOS
Troubleshooting
Commands
· ping 127.0.0.1
· tracert
· ipconfig/all
· arp -a
Class Ranges
Class A - 1-126 - network.node.node.node
Class B - 128-191 - network.network.node.node
Class C - 192-223 - network.network.network.node
Private Address Ranges
Class A - 10.0.0.0 - 10.255.255.255
Class B - 172.16.0.0 - 172.31.255.255
Class C - 192.168.0.0 - 192.168.255.255
IP Classes
Application - Identifying and establishing the
availability of intended communication partner
and whether there are sufficient resources
Presentation - Data translation, encryption,
code formatting
Session - Setting up, managing and tearing
down sessions. Keeps application’s data
separate
Transport - Provides end-to-end
transport services - establishes logical
connections between hosts. Connection-
oriented or connectionless data transfer.
Network - Manages logical addressing
and path determination
Data Link - Provides physical
transmission of data, handles error
notification, flow control and network
topology. Split into two sub layers (LLC
and MAC)
Physical - Specifies electrical,
mechanical, procedural and functional
requirements for activating, maintaining
and deactivating a physical link.
OSI Reference Model Process/Application layer
FTP - TCP file transfer service port 20-21
Telnet - Terminal emulation program port
23
TFTP - UDP file transfer port 69
SMTP - Send email service port 25
DHCP Assigns IP addresses to hosts
ports 67 and 68
DNS Resolves FQDNs to IP addresses
port 53
Host-to-Host layer
TCP - Connection-oriented protocol, provides
reliable connections (acknowledgments, flow
control, windowing)
UDP - Connectionless protocol, low
overhead but unreliable
TCP/IP Model Protocol Suite
Internet layer
IP - connectionless protocol, provides
network addressing and routing
ARP - finds MAC addresses from known IPs
RARP - finds IPs from known MAC
addresses
ICMP - provides diagnostics, used by ping
and traceroute
Network Access
Patch Cable Types
255.0.0.0 /8
255.128.0.0 /9
255.192.0.0 /10
255.224.0.0 /11
255.240.0.0 /12
255.248.0.0 /13
255.252.0.0 /14
255.254.0.0 /15
255.255.0.0 /16
255.255.128.0 /17
255.255.192.0 /18
255.255.224.0 /19
255.255.240.0 /20
255.255.248.0 /21
255.255.252.0 /22
255.255.254.0 /23
255.255.255.0 /24
255.255.255.128 /25
255.255.255.192 /26
255.255.255.224 /27
255.255.255.240 /28
255.255.255.248 /29
255.255.255.252 /30
© Copyright 2010 Internetwork Training Although the authors of have made every effort to ensure the information in this document is correct, the authors do not assume and hereby disclaim any liability to any party for loss or damage caused by errors, omissions or misleading information.
CCNA Cheat Sheet
Internetworking Essentials
Segmen
t
bits frame packet
Protocol Data Units (PDUs)
CIDR Notation (Classless Inter-Domain Routing)
Cisco Trace Command & Responses
Router> traceroute 172.15.9.1
* Timed out
!H Router received packet but did not forward it
N Network unreachable
P Protocol unreachable
U Port unreachable
Cisco Ping & Response Codes
Router> ping 172.15.9.1
! Success
. Timed out waiting for reply
U Destination unreachable
| Ping process interrupted
? Unknown packet type
C Congestion-experienced
& Time to live exceeded
General Troubleshooting
Bus Topology
· All devices on a single wire (coaxial)
· A cable fault can bring network down
Ring Topology
· All devices connect to each other in a circle
· A cable fault can bring network down
· Can be configured with a second ring for
redundancy
· Difficult to expand network
Star Topology
· Most common physical topology
· All devices connect to a central hub/switch
· Cable faults don’t bring the whole network down
· Easily expandable
· Requires more cabling than bus or ring
· Hub/switch is a central point of failure
Mesh Topology
· Every device is directly connected to every other
device
· Complete redundancy
· Uses the most cable compared to other topologies
· Expanding the network can be problematic
Physical Network Topologies
Bus (broadcast) logical topology
· Most commonly used logical topology
· Broadcasts data to all nodes on the network
· Contention-based
Logical Topologies
Token (ring) logical topology
· A token is passed from one device to the next
· Devices can only transmit when they have the
token
· Each device checks the token to see if the data
inside is for them
· Slower than logical bus topology
· No longer used
Physical Layer (Layer 1) Devices
These devices extend collision domains, increase traffic problems and reduce network bandwidth.
· Transceivers Connect one media type to another e.g. Fiber to copper
· Repeaters Used to extend the reach of a network segment
· Hubs These are multiport repeaters. Used to share a single network segment with many devices. Only one device
can transmit at any one time
Network Devices
Data Link Layer (Layer 2) Devices
Filter traffic on the LAN by MAC (hardware) address. They break up collision domains, increase available bandwidth to
devices and reduce LAN traffic problems.
· Bridges Connect two network segments together and filter data between them
· Switches These work like multiport bridges. Each connected device can transmit simultaneously unlike hubs
· Network Interface Cards (NICs) Allow a device to connect to the network. Contains a unique 48-bit MAC address.
· Access Points These allow devices to connect to the network wirelessly
Network Layer (Layer 3) Devices
Route traffic between networks by logical network addresses. They use path determination to select the best route to a
destination. They break up collision domains and broadcast domains.
· Routers Connect different networks to one another and make routing decisions based on one or more metrics to
decide the best path
Network Media (Cabling)
Coaxial Cable
10Base5 (Thicknet) Original Ethernet cabling media. Up to 500m per segment. Highly resistant to EMI. Uses physical
and logical bus topology with clients connecting using vampire clasps. Data transmission up to 10Mbps. Now obsolete.
10Base2 (Thinnet) Replaced Thicknet because it was lighter and thinner and easier to work with. Up to 185m per
segment. Uses physical and logical bus topology with clients attaching using BNC and T connectors. Data transmission up
to 10Mbps. Now obsolete.
Optical Fiber
100BaseFX Uses 62.5/125-micron multimode fiber. Maximum length 412m. Uses ST or SC connectors.
1000BaseSX Uses 62.5/50-micron multimode fiber. Maximum length 220m 550m.
1000BaseLX Uses 9-micron single-mode fiber. Maximum length between 3 - 10km.
Twisted Pair Cable
10BaseT Uses two-pair unshielded twisted-pair (UTP) wiring. Up to 100m per segment. Uses RJ45 connectors. Physical
star with logical bus topology. Use EIA/TIA category 3 cable. Data transmission up to 10Mbps.
100BaseTX Uses two-pair UTP wiring. Up to 100m per segment. Uses RJ45 MII connectors. Physical star with logical
bus topology. Use EIA/TIA category 5, 6 or 7 cable. Data transmission up to 100Mbps
1000BaseT Uses four-pair UTP wiring. Up to 100m per segment. Use EIA/TIA category 5 or 5e cable. Data transmission
up to 1000Mbps
1000BaseCX Uses copper twisted-pair (twinax). Maximum length 25m.
© Copyright 2010 Internetwork Training Although the authors of have made every effort to ensure the information in this document is correct, the authors do not assume and hereby disclaim any liability to any party for loss or damage caused by errors, omissions or misleading information.
www.InternetworkTraining.com
Free Cisco CCNA Flash Cards
Carrier Sense Multiple Access Collision Avoidance
(CSMA/CA)
· Used in wireless networking
· Proactive algorithm
· High overhead
Carrier Sense Multiple Access Collision Detection
(CSMA/CD)
· Used in wired Ethernet networks
· Reactive algorithm
Straight-through cable - Use 568B pinouts on
both ends of a cable
Crossover cable Use 568A on one end and
568B on the other end of a cable
Remembering colours for 568B:
Only Good Boys Get Brownies”
Orange, Green, Blue, Green, Brown
568A pinouts reverse the orange and green pair.
EIA/TIA 568A and 568B Standards
Assemble a frame
Start
Transmit 1st bit of
frame
Is another device
transmitting?
Yes
No
Collision
detected?
No
Transmission
Finished?
Transmit next
bit of frame
No
End
Yes
Collision recovery
algorithm
Yes
Recovered
Assemble a frame
Start
Transmit RTS
Is the
channel idle?
Yes
CTS Received?
Yes
End
Wait for random
back-off time
Transmit Data
No
No
802.3 (Ethernet)
· Physical bus/star,
logical bus
· Coaxial or twisted
pair
· 10 Mbps
802.3u (Fast Ethernet)
· Physical star, logical
bus
· Twisted pair
· 100 Mbps
802.3ab (Gigabit
Ethernet)
· Physical star,
logical bus
· Twisted pair
· 1000 Mbps (250
Mbps per pair)
LAN Standards
802.3z (Gigabit
Ethernet)
· Physical star, logical
bus
· Twisted pair, optical
fiber, or twinax
· 1000 Mbps
802.4 (Token Bus)
· Physical bus,
logical ring
· Coaxial
· 4 Mbps
802.5 (Token Ring)
· Physical ring, logical
ring
· Twisted pair
· 4 or 16 Mbps
Switch Modes
Cut through Forwards the frame straight after the
destination address has been read. Very fast, but can
forward frames with errors.
Store and forward Reads the entire frame prior to
forwarding. Performs error an check, but adds latency
to transmission. Most new switches use this mode
because it can cater for hosts running at different
speeds.
Fragment Free Forwards the frame after reading the
first 64 bytes to avoid forwarding frames with errors.
© Copyright 2010 Internetwork Training Although the authors of have made every effort to ensure the information in this document is correct, the authors do not assume and hereby disclaim any liability to any party for loss or damage caused by errors, omissions or misleading information.
Catalyst Switch Boot Sequence + Operation
1.) POST (error indicated with amber SYST LED).
2.) Load IOS from Flash.
3.) Configuration file copied from NVRAM to RAM.
4.) Floods all frames it receives out all ports (CAM table
empty).
5.) Begins to populate CAM table (port address table) as it
learns which devices are attached to its ports.
6.) Before forwarding a frame it will check the CAM table, if an
entry exists for the destination address it will forward the
frame out of the port that the destination is connected. If no
entry exists it will flood the frame out of all ports.
7.) Will always flood multicast and broadcast messages,
unicast message are filtered.
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Description
CCNA Cheat SheetOSI Model vs TCPIP ModelInternetworking EssentialsTCPIP Model Protocol SuiteOSI Reference ModelProcessApplication layerGeneral Troubleshooting ApplicationIdentifying and establishing the FTPTCP file transfer serviceport 2021availability of intended communication partner Cisco PingResponse CodesTelnetTerminal emulation programport Troubleshooting Stepsand whether there are sufficient resources23Router ping 1721591TFTPUDP file transferport 69 Success1 Ping 127001 SMTPSend email serviceport 25PresentationData translation encryption Timed out waiting for replyLoopbackDHCPAssigns IP addresses to hostscode formattingU Destination unreachable2 Ping default gatewayports 67 and 68 Ping process interrupted3 Ping remote deviceDNSResolves FQDNs to IP addresses Unknown packet typeSessionSetting up managing and tearing port 53 C Congestionexperienceddown sessions Keeps applications dataTime to live exceededseparateHosttoHost layerWindows DOS Cisco Trace CommandResponsesTCPConnectionoriented protocol provides TransportProvides endtoend nTroubleshooting ereliable connections acknowledgments flow transport servicesestablishes logical mRouter traceroute 1721591tCommandsgcontrol windowingeconnections between hosts ConnectionSUDPConnectionless protocol low Timed outoriented or connectionless data transfer ping 127001overhead but unreliable H Router received packet but did not forward its tracertUt N Network unreachableeD ipconfigallkNetworkManages logical addressingP Protocol unreachablePcaarp aand path determinationpsInternet layer U Port unreachabletinIPconnectionless protocol provides U Data LinkProvides physical network addressing and routingatIP Classeseatransmission of data handles error ARPfinds MAC addresses from known IPsmD alnotification flow control and network RARPfinds IPs from known MAC rfoClass RangesctopologySplit into two sub layers LLC addressesotand MACoICMPprovides diagnostics used by ping rClass A1126networknodenodenodePand tracerouteClass B128191networknetworknodenodePhysicalSpecifies electrical Class C192223networknetworknetworknodestmechanical procedural and functional ibrequirements for activating maintaining Network AccessPrivate Address Rangesand deactivating a physical linkClass A1000010255255255Class B172160017231255255Half Duplex Ethernet shares a collision Cisco 3Layer Hierarchical ModelClass C19216800192168255255domain resulting in lower throughput than Full Duplex Ethernet which CIDR Notation Classless InterDomain RoutingCoreBackbone common to all users needs to be as fast as possible requires a pointtopoint link between and fault tolerant avoid ACL VLAN trunking and packet filtering here two compatible nodes255000 82552552400 20DistributionRoutingprovides access control policies filtering WAN 2551280092552552480 21Causes of LAN congestionBroadcast access and VLAN trunking25519200102552552520 22storms too many hosts with a broadcast 25522400 11AccessSwitchingUser and workgroup access segmentation2552552540 23domain multicasting low bandwidth 25524000122552552550 24bottlenecks2552480013255255255128 2525525200 14Patch Cable Types255255255192 26Collision domainSwitchesbridges 25525400 15255255255224 27breakup collision domains hubs extend StraightthroughConnect PC to hub or switch router to switch or 25525500 16255255255240 28them2552551280 17hub255255255248 292552551920 18CrossoverConnect hub to hub switch to switchPC to PC255255255252 30Broadcast domainsRouters and 2552552240 19RolledConsole connection for PC to routerVLANs breakup broadcast domains Copyright 2010 Internetwork TrainingAlthough the authors of have made every effort to ensure the information in this document is correct the authors do not assume and hereby disclaim any liability to any party for loss or damage caused by errors omissions or misleading information
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