IS452 Exam2Review

• ○Address Resolution Protocol
• ○ Data traffic is routed using the network addresses
• ○ Data traffic is forwarded over a physical network using MAC addresses
• ○ ARP is a method used in TCP/IP suite to map network addresses to MAC addresses

• unicast
• multicast
• broadcast
• connection oriented
• connectionless oriented

§ Single packet from source to destination

§ Single packet that is sent to a specific subset of nodes

§ Single packet that is sent to all nodes

• -must first establish a connection before sending data
• § Connection Establishment, data transfer, and connection termination
• § Method used for TCP

• - can send the data without the need to establish a connection
• § Transfer can simply send the data without the added overhead
• § Method used for UDP

• ○ A high-speed network that is bounded by a small geographic area
• □ Tends to encompass one broadcast domain
• □ Usually restricted to a building or floor
• □ Operates at the layer 1 and 2 of the OSI model
• □ Interconnected using a hub or switch

• ® Most commonly used
• ® Duplex – full/half
• ® Speed – 10/100/auto

• ○ Segment – Transport layer (Layer 4)
• ○ Packet – Network Layer (Layer 3)
• ○ Frame – Data Link Layer (Layer 2)

• access layer
• distribution layer
• core layer

• ○ This is the bottom layer of the 3 layer network design
• ○ Users are connected at this layer
• ○ Collision domains can be limited through VLANs

• ○ Routing (or at the Core Layer)
• ○ Packet Filtering
• ○ QOS

○ High speed data transfers and reliability

• ○ Cisco switches can be modular in the number of ports they allow or non-modular
• § Non-Modular come in different sizes but the sizes are fixed and cannot be expanded

• ○ A LAN not restricted by physical location
• § Can be developed based on more than physical location

• § Performance
• § Formation of virtual workgroups
• § Easy Administration
• § Cost
• § Security

• § Switch ports are joined to a VLAN based on the workstation’s MAC address
• § Cisco Works 2000 or VLAN Management Policy Server (VMPS) can be used to associate MAC addresses to VLANS
• § Management is a headache in large networks

• § Membership is based on the VLAN that a switch port belongs to
• □ Every port is configured to be belong to a VLAN
• § Static VLANs allow for tighter control of resources and user movement
• § Easy management
• □ No need to maintain large MAC address tables

• § OS loaded on Switches
• § Older OS and Cisco is working to move away from CatOS and to IOS
• □ IOS is used on routers
• § New equipment shipped comes with IOS

• ○ Ethernet has limits of 100 meters
• § Wiring runs longer than 100 meters could cause service failures

• ○ A method to support multiple VLANs that have members on more than one switch
• ○ Switches tag each frame so that the receiving switch knows which VLAN the frame belongs to

• § Cisco Inter-Switch Link (ISL)
• § IEEE 802.1q

• § ISL created before IEEE standardized a trunking protocol
• § ISL is a Cisco proprietary so it can only be used between Cisco switches
• § ISL encapsulates each Ethernet frame with an ISL header and trailer
• □ ISL header is 26 bytes
• ® VLAN number is encoded in header
• □ ISL trailer is 4 bytes CRC

• § Developed in 1998
• § Actual frame is modified or tagged
• □ 4 bytes are added to the original Ethernet header
• ® A field within this header identifies the VLAN number
• § FCS is recalculated

• Dynamic Trunk Protocol (DTP)
• ○ DTP is the process that takes place to determine whether tow connecting devices can create a trunk connection
• § Supports auto-negotiations for both ISL and 802.1q

• • VLAN Trunking Protocol (VTP)
• ○ VTP is a Cisco proprietary messaging protocol that occurs between devices on trunk ports
• § Allows VLAN information to be propagated across your switched network so you have a consistent VLAN configuration
• § Makes management easy
• □ Propagates across mixed media

□ A management domain is a grouping of switches that will be sharing information about VLANs

• □ Server- Responsible for making all VLAN configurations (adds/changes/deletions)
• □ Client- Accepts VTP messages
• □ Transparent- Do not participate in management domain but do forward messages

• § Summary- Generated every 300 seconds to ensure all switches are in sync; -Contains a revision number
• § Request- Generated to acquire VLAN information
• § Subset- Generated in response to a request

• § Allows a switch to make intelligent decisions concerning the forwarding of multicast, broadcast, and unknown destinations across trunk ports
• § Turned off by default
• § Switch must be in Server mode
• § Pruning can be done manually

• • Spanning Tree Protocol (STP)
• ○ A protocol developed to prevent loops
• § Places a port in either blocking or forwarding state
• □ Ports that are in forwarding state can send and receive frames
• § Traffic has to take longer paths

• ○ STP selects a root bridge
• § All interfaces on the root bridge in forwarding state
• ○ All other bridges select a port that has the least administrative cost between itself and the root bridge.
• § This port is called the root port
• ○ Every port is configured to be belong to a VLAN
• ○ All switches send out bridge protocol data units (BPDU) with the following information
• § Root bridge’s ID ID (MAC address+priority)
• □ Default priority is 32768
• § Cost to reach the root
• § Bridge ID of the sender
• ○ Bridge with the lowest ID becomes the root bridge

• § How long a root waits before sending periodic hello BPDUs.
• □ Default is 2 seconds

• § How long a bridge should wait, after beginning to not hear hellos, before trying to change the STP topology
• □ Default is 20 seconds

§ Delay that affects the time involved when an interface changes from blocking state to forwarding state

§ When configured it skips the STP port states and places the port into forwarding state immediately

• ARP (Address Resolution Protocol)
• 1. Host A want to send data to host B
• 2. Host A checks to see if it has the ARP entry for Host B - NO.
• 3. • Host A places the original packet in buffer
• • Host A creates the ARP Broadcast and sends it
• 4. • Host B now processes the ARP request
• ○ Host B first saves the MAC address and IP for Host A in its own ARP table
• 5. Host B now can respond to the ARP request
• 6. • Host A receives the ARP reply and can now complete the original packet
• ○ Host A will save the MAC and IP for Host B in its ARP Table
• 7. Host A now builds the packet with Layer 3 and 2 information to transmit

• • MAC-Address Table
• ○ When this request is sent, the switch saves the MAC Address for Host A and assigns it to Port 1
• ○ When this reply is sent, the switch saves the MAC address for Host B and assigns it to Port 2

• -Cheap and Ubiquitous
• ○ Successor to Category 5, which itself is a successor to Category 3
• ○ Speeds up to 1 Gbps
• ○ Requires 2 pair for 10/100, 4 pair for 1Gb
• ○ Maximum segment length of 100m
• ○ Also used for voice communications in newer building installations
• ○ Power over Ethernet is possible
• ○ Small cable diameter, easy to field terminate

• § Speeds up to 10Gbps
• § Requires 4 pairs
• § Maximum segment length of 100m
• § Much tighter controls on installation standards make field terminations significantly harder
• § More attention is paid to eliminate NEXT (near-end crosstalk), ANEXT (alien near-end crosstalk) and PSNEXT (power-sum near-end crosstalk)

• § Speeds up to 100Gbps at 15 meters, potentially 100 meters as electronics improve
• § Bandwidth up to 1GHz means potential for broadband cable television
• § Individually shielded pairs, as well as shielded cable

• Ride the Light
• ○ Speeds of 10, 40, 100Gbps and higher
• ○ Distances of hundreds of miles or more
• ○ Use highly tuned, single-mode laser optics
• ○ Smaller core size greatly reduces modal dispersion
• ○ Typically used for connections between buildings, and even further distances

• Ride the Light
• ○ Speeds up to 10Gbps
• ○ Distances up to 2km
• ○ Can be used with LEDs instead of lasers, making optics much cheaper
• ○ Larger core size enhances modal dispersion; the signal can become spread in time
• ○ Typically used for connections within a building

• Wireless
• The Standard We All Know and Love

• § Introduced in 1999
• § Bit rates of 1-11 Mbps
• § 11 20MHz channels in the 2.4GHz band
• § Three non-overlapping channels (1, 6, 11)
• § Lower frequency means greater range, can traverse solid objects easier
• § Interference issues (microwave ovens, Bluetooth devices, wireless keyboards/mice)

• § Introduced in 1999
• § Bit rates of 6-54 Mbps
• § 21 20MHz channels in the 5GHz band
• § 21 non-overlapping channels
• § Higher frequency is more susceptible to absorption by surrounding objects
• § Fewer interference issues

• § Introduced in 2003
• § Bit rates of 6-54 Mbps
• § 11 20MHz channels in the 2.4GHz band
• § 3 non-overlapping channels
• § Same strengths and weaknesses as 802.11b
• § Cheaper manufacturing costs make this standard a commodity

• § Drafted in 2007, ratified 2009
• § Bit rates of 300Mbps and higher with channel bonding
• § 3 20MHz channels in the 2.4GHz band, 21 20MHz channels in the 5GHz band
• § 24 non-overlapping 20MHz channels
• § MIMO (multiple in-multiple out) uses multiple antennas for higher bandwidth and more recently beamforming
• § Multiple antennas cost more, and many manufacturers only implement the 2.4GHz standard, keeping the same limitations as 802.11b and 802.11g.

• § Still in draft status, anticipated ratification in 2014
• § Single stream bit rates of up to 866Mbps
• § Up to 8 spatial streams instead of 4 in 802.11n
• § 3 20MHz channels in the 2.4GHz band, 21 20MHz channels in the 5GHz band
• § 24 non-overlapping 20MHz channels
• § MIMO (multiple in-multiple out) uses multiple antennas for higher bandwidth
• § Uses more dense 256-QAM modulation, over 64-QAM used in 802.11n
• § Gigabit wireless to multiple users possible

• § Very high frequencies, very high potential bandwidth
• § Expensive to deploy, frequency licensing may be an issue
• § Limited to point-to-point links
• § Links can be dozens of miles apart

• § Uses lasers to transmit data, very high (up to 10Gb) bandwidth
• § Expensive to deploy, costly equipment
• § Limited to point-to-point links, can be affected by weather
• § Links can be miles apart

• § Also uses light to transmit data, but bandwidth is not as high
• § Cheaper to deploy
• § Limited to point-to-point links
• § Links have limited distance

• § HSPA+ (most commonly used by AT&T and T-Mobile)
• □ Theoretical throughput capacity of 672 Mbps
• § LTE (most commonly used by Verizon, and now by Sprint Nextel and AT&T)
• □ Theoretical throughput capacity (with LTE-Advanced update) of 1Gbps

• § Primarily used to create (relatively) low data speed personal area networks
• § Also used for wireless keyboards, mice, headsets

• -Other IEEE Standards; What’s to Come
• ○ Drafted in 2001, ratified in 2004, currently in use as 802.16-2009
• ○ Also known as WiMAX or WirelessMAN, it is meant to operate at microwave frequencies (10-63GHz)
• ○ Speeds up to 128Mbps for mobile and 1Gbps for fixed stations but at a much greater range, up to 50 miles

• -Other IEEE Standards; What’s to Come
• ○ Published in 2008
• ○ Also known as MBWA (mobile broadband wireless access), it is meant to provide up to 80Mbps access to clients moving up to 250km/h
• ○ Operates in licensed frequencies below 3.5GHz

• -Other IEEE Standards; What’s to Come
• ○ Published in July, 2011
• ○ Also known as WRAN (wireless regional area network), aims to use white spaces in current television broadcast spectrum
• ○ Can be used to help get access to people still too far from traditional broadband technologies (DSL, cable, etc.)