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155 Cards in this Set

  • Front
  • Back
Legacy networks—an existing mainframe/minicomputer environment.
- Centralized environment (all processing takes place at central computer)
- Dumb terminals
- Most applications custom built
- Support staff needed
- Incremental growth expensive
Peer to peer (also known as workgroups)
- Each member acts both like a server and workstation. Resource and security handled at individual system level.
- Workstations normally store their own applications (data files)
- Each node talks to all other nodes
- Limited security
- 10 or less nodes
Client/Server
- Application/data files can be stored on server
- Files downloaded to intelligent workstations (clients) for processing
- Results uploaded to server for storage
LAN vs. Mainframe
- LAN’s less expensive to implement
- Supports a wide range of off-the-shelf products.
- Incorporate a modular design that makes incremental expansion possible with ease.
CAN
Campus Area Network (networks in geographically contiguous buildings)
MAN
Metropolitan Area Network (Connects networks that are non-contiguous, but located within a calling area. Local telephone companies or alternate service providers (ASP) supply facilities to link locations together.
WAN
Wide Area Network (links networks that are located in different local calling areas, known as Local Access Transport Areas (LATA’s).
Servers
– network operating systems (NOS) turns personal computers into servers. Some NOS, like Novell Netware, need a dedicated server (cannot be used for anything else).
Workstation
PC that is connected to a network.
Host
any network device that has a TCP/IP address. Can be a server, workstation, or a peripheral device such as a printer, print server, or fax server.
NOS
Runtime version of a NOS is a minimal implementation that provides basic file sharing and network access, along with benefits of a NOS file caching scheme. (Example is a CD server).
Groupware
email package that provides more functionality. Examples are Microsoft Exchange, Novell GroupWise, and Lotus Notes.
Bus topology
- Commonly use coaxial as transmission medium
- Traditionally, Ethernet uses bus topology
Ring topology
- Repeaters at each node repeat the signals.
Star topology
- Hub in center, each node connected to hub.
Mesh topology
- Hybrid of partial mesh is generally used for interconnecting only most important sites with multiple links.
- Advantages: easy to troubleshoot, isolation of network failure is easy, fault tolerance maximized by rerouting traffic around failed links.
- Disadvantages: difficult to install and reconfigure, expensive because of redundant connections and wasted bandwidth.
Planning for a network. A plan provides:
- Method for verifying all business and technical requirements will be met prior to implementation.
- Roadmap for network implementation.
- Historical reference of the network design for future use.
Creating a plan
- Determine what business requirements must be met
- Review current infrastructure, if one exists
- Review new/existing technologies that can meet business needs.
- Determine appropriate infrastructure requirements and changes.
- Document the design
- Review documentation with appropriate technical and business personnel and modify as necessary.
Application layer
provides series of definitions to provide network-wide system management functions for software (file transfer, database, email, etc..)
Presentation layer
translates data into appropriate transmission format. Data encryption and compression. Terminal emulation.
Session layer
responsible for the integrity of logical connection of software session. Provides synchronization.
Transport layer
responsible for accuracy of the data transmission. Handles and recovers from errors.
Network layer
establishes unique network address and manages transport of information packages between networks. Bundles small frames together.
Data Link layer
specifies how devices attached to network gain access to various computing resources. Packages data into frames.
- Logical Link Control (LLC) – 802.2 Provides software controls to manage multiple protocols that are simultaneously accessing network. Acts like umbrella protocol for various MAC sub layers.
- Media Access Control (MAC) – physically defines how devices control access to the network. Defines network adapter interface options, cable types, and access methods. (802.3, 802.4 (token bus), 802.5 (token ring)).
Physical layer
governs how data is transmitted over a media (cable and connectors).
Network adaptor settings
- IRQ (should have its own). 3, 5, 10 commonly used.
- I /O address
- DMA. Some devices need to address system memory directly. ISA/EISA/MCA have 8 DMA channels available.
- ROM address. ROM BIOS must be given unique memory address. If adaptor doesn’t give you ability to change address, you may have to reconfigure existing devices.
MAC address
– 48-bit, 12 hexadecimal number (example: 00-A0-00-E2-8F-FA)
- First 3 portions denote vendor (00-A0-00 in example)
- Last 3 unique hex ID (E2-8F-FA in example)
Boot PROM (programmable read only memory)
- Add on item to a network adaptor that helps a computer to boot entirely from network server.
Configuring a network adaptor:
- Jumpers/switches
- Software config
- PnP. Must have PnP BIOS, must report to BIOS what IRQ and I/O address it is using or able to use, and accept commands from BIOS, and must have PnP operating system
- NDIS (Network Device Interface Specification).
o Developed by Microsoft and 3Com
o Industry standard, needs NDIS compliant adaptor driver
o NDIS 3.0 supports unlimited adaptors and protocols bound to each adaptor.
o Associates NDIS protocols with adaptor through “binding”.
- ODI (Open Datalink Interface)
o Unique to Novell Netware
o Needs ODI compliant driver
o Associates ODI protocols with adaptor through “binding”.
802.0 protocol
Executive committee
802.1 protocol
Higher layer interfaces
802.2 protocol
Logical Link Control
802.3 protocol
Ethernet CSMA/CD
802.3z Gigabit Ethernet
802.3ae 10Gigabit Ethernet
802.4 protocol
Token Bus
802.5 protocol
Token Ring
802.6 protocol
Metropolitan Area Network (MAN)
802.7 protocol
Broadband LAN
802.8 protocol
Fiber Optic LAN
802.9 protocol
Integrated voice and data LAN
802.10 protocol
Standards for interoperable LAN security
802.11 protocol
Wireless networks
802.12 protocol
Demand Priority Access LAN, 100baseVG-Anylan
Data Link layer
- MAC layer
o Responsible for delivering error-free data between two computers on a network. Defined by 802 as communicating directly with the network adaptor.
o Functionality defined under 802.3 and 802.5
- LLC (Logical Link Control)
o Defined by 802 as managing data link communications. Also defines use of logical interface points, called Service Access Points that can be referenced by other computers to transfer information from LLC layer to upper OSI layers.
o Functionality defined under 802.2
CSMA/CD
- Carrier Sensing – listens to someone talking
- Multiple Access – all have concurrent access to media
- Collision Detection – if two or more systems transmit at once, system will detect and repeat message after a short interval.
CSMA/CA
- Collision Avoidance
- Does not detect collisions but attempts to avoid it. Alert message notifies nodes of an impending transmission.
10baseT
Baseband, cat 3 or better, 100m max distance, RJ-45
10baseFL
Baseband, fiber optic, 2000m max distance, uses different connectors such as ST or SC. Logical Bus, physical star
100baseTX
baseband, cat 5, 100m, RJ-45
100baseFX
FDDI, baseband, fiber optic, 2000m max distance
1000baseTX
gigabit, cat 5, 100m
1000baseCX
gigabit, STP, 25m max distance
1000baseSX
gigabit, fiber optic, 550m
1000baseLX
gigabit, fiber (book says Cat 5, but it’s wrong), 5000m
10GbaseSR
10 gigabit, multimode fiber optic, 82m max distance, full duplex
10GbaseLR
10 gigabit, single mode fiber optic, 10 kilometers
10GbaseER
10 gigabit, single mode fiber optic, 40 kilometers
Token ring is similar to 802.5 but not identical whats the difference?
- Logical ring wired as physical star
- Transfer rate of 4 to 16mbps
- UTP/STP/fiber optic
- Deterministic (possible to predict passage of token). Good for timing critical and control applications.
describe Token ring passing
- Only one active token on ring at any time
- Tokens travel at thousands of miles per second (fiber)
- Token passes from system to system
- System can attach data to a token when token is free
- Each system receives/regenerates token
token ring Topology
- Each node up to 100m from MSAU using UTP, or 45m with STP. Minimum for both is 2.5m
- Each MSAU can support 72 workstations using UTP, or 260 with STP
- Each ring can have 33 MSAU’s.
what is the token in token ring
Token is a control signal (single bit) that is passed from station to station between transferring of data.
Passing of token. How does it work
- Station takes token, flags it as busy (bit set to 1), loads it with data and passes it on.
- Frame makes it way to receiver, takes data, marks frame as received and passes it on.
- Original sender sees receipt and removes frame, releases new token.
- Option called early token release permits transmitting station to release token after transmitting ending delimiter of frame
whar is token ring active monitor
- First station that powers up on ring. All others on standby. Next is chosen by highest address. Active monitor sends signal every 7 seconds or less to announce its presence.
o Responsible for verifying token is detected on ring and generates new one if it’s missing.
o Removes continuously recirculating frames.
what is Beaconing
- Used for hard errors. When detected, a station transmits beacon frames. Beacon frame is used to define failure domain. Failure domain includes station reporting failure, nearest active upstream neighbor (NAUN), and everything in between.
- After it’s identified, NAUN removes itself from ring and begins self test. If successful, it reconnects. It not, beaconing station removes from ring and self tests. If ring doesn’t recover, manual intervention is necessary.
FDDI
- Uses double fiber ring, runs at 100mbps. Typically used as backbone connecting buildings on a campus or wider area, up to 60 miles apart.
- Two complete rings, secondary is for redundancy.
ATM (Asynchronous Transfer Mode)
- Can reach throughput of 10000Mbps, but more commonly used for 622mpbs or 155 mpbs.
- Small packets (cells) of fixed size. 48 bytes of data with 5 byte header
- Does not use routing like ethernet, but ATM switches (point to point connections).
- 802.11
o Up to 2mbps, FHSS/DSSS 2.4 Ghz
- 802.11a
o Up to 54mbps, OFDM, 5 Ghz
- 802.11b
o Up to 11mbps, DSSS, 2.4 Ghz
- 802.11g
o 11/54 Mbps, OFDM (backwards with 802.11a), DSSS (backwards with 802.11b)
FHSS (Frequency Hopping Spread Spectrum)
- Data transmitted on a single frequency at any given time. However, signal hops from frequency to frequency. Pattern may seem random, but actually generated by a computation known to both sender and receiver, to reduce interference from other nearby transmissions.
DSSS (Direct Sequence Spread Spectrum
- Data being transmitted is spread over multiple frequencies, allowing faster throughput.
OFDM (Orthogonal Frequency Division Multiplexing)
- Radio signal is split into smaller, multiple signals, and then transmitted at the same time, at different frequencies. Operates at 5 Ghz and signal distance is shorter.
Bluetooth
- Uses FHSSS and interferes with 802.11x
Infrared
- Up to 10-20 feet, up to 4mbps
Connectionless protocol
- Typically for data less than 1kb
- Acknowledgement of each receipt not necessary
Connection Orientated
- For larger files, uses packet sequence numbers to verify packet order and acknowledge receipt of each packet
NetBEUI
- Small networks (20-200 nodes), good error protection, connectionless and connection-orientated
- Non routable
- Uses SMB (server message block) to share resources
NetBIOS
- Application interface operating at session layer, rather than a protocl
IPX/SPX
- IPX runs under network layer, provides connectionless services
- SPX runs under transport layer. Provides connection-orientated.
o Controls protocol error checking, windowing, flow control
- Uses two different frame types (802.2 & 802.3)
o Cannot communicate with each other
o 802.3 used by Netware 3.1x and earlier
o 802.2 used by Netware 4.x and later

o Win 95, Win 98 and Win NT/2000 automatically configure IPX/SPX protocol to use the frame type first received by network on boot. This works well when there is only one version of Netware running. When more than one version of Netware (different versions) is running, you may have some problems with conflicting frame types:
 An incorrect frame type may or may not see some netware servers, or unable to see any Netware servers but browse other network resources.
 To remedy this problem, use network property sheet for IPX/SPX protocol and manually select correct frame type
NWNBLink (NetBIOS over IPX
- Can be used to communicate and share files between systems on any windows-based network
- Fully routable protocol.
TCP/IP
- IP is unreliable connectionless protocol. Sole function of IP is to transmit TCP/IP
- TCP provides acknowledged, connection orientated, and guaranteed delivery.
o Retransmits on error
o FTP depends on TCP
- UDP (user datagram protocol)
o Designed for connectionless, unacknowledged communications.
o Uses IP as underlying protocol
o UDP adds information about source and destination socket ID’s.
o TFTP (trivial file transfer protocol) depends on UDP
Gateways
- Connects incompatible networks by translating protocols
Remote Access Protocols - SLIP (Serial Line Internet Protocol)
o Defines a sequence of characters that frame IP packets over serial line
o Originally in the 3COM UNET TCP/IP implementation
o Slow communications (less thank 19.2k)
o Lack of error detection and correction, lack of compression, inability to provide packet addressing and packet ID information.
Remote Access Protocols - PPP (Point to Point Protocol) consists of 3 main components
o Methodology for encapsulating multiprotocol datagrams
o Link Control Protocol (LCP) for establishing, configuring, testing data link connection
o Family of Network Control Protocols (NCP) for establishing, configuring different network layer protocols
 PPP supports multiple transport protocols, therefore it allows compressions, link quality monitoring, security features, error detection and correction, and encryption
Remote Access Protocols - PPTP (Point to Point Tunneling protocol)
o Allows secure communication through virtual private networks
Remote Access Protocols - RDP (Remote Desktop Protocol)
o Part of Windows NT terminal server and Windows 2000/Server 2003 terminal server
o Default port is 3389
o Operates on application layer
Security Protocols - IPSec
o Actually a suite of protocols used to encrypt packets.
o Transport mode – only data portion of packet is encrypted, not header
 Less secure than tunnel mode
o Tunnel mode – both data and header are encrypted
-Security Protocols L2TP (Layer 2 tunneling protocol)
o Extension to PPP
o Enhanced tunneling protocol used in VPN. Optimized to work with Ipv6 and IPSec
o Operates at Data Link of OSI layer
Security Protocols - SSL (Secure socket layer)
o Developed by Netscape.
o A private a public key system (RSA) is used to encrypt/decrypt data
 Messages encrypted using receiver’s public key, then decrypted with receiver’s private key
Passing of token. How does it work
- Station takes token, flags it as busy (bit set to 1), loads it with data and passes it on.
- Frame makes it way to receiver, takes data, marks frame as received and passes it on.
- Original sender sees receipt and removes frame, releases new token.
- Option called early token release permits transmitting station to release token after transmitting ending delimiter of frame
whar is token ring active monitor
- First station that powers up on ring. All others on standby. Next is chosen by highest address. Active monitor sends signal every 7 seconds or less to announce its presence.
o Responsible for verifying token is detected on ring and generates new one if it’s missing.
o Removes continuously recirculating frames.
what is Beaconing
- Used for hard errors. When detected, a station transmits beacon frames. Beacon frame is used to define failure domain. Failure domain includes station reporting failure, nearest active upstream neighbor (NAUN), and everything in between.
- After it’s identified, NAUN removes itself from ring and begins self test. If successful, it reconnects. It not, beaconing station removes from ring and self tests. If ring doesn’t recover, manual intervention is necessary.
FDDI
- Uses double fiber ring, runs at 100mbps. Typically used as backbone connecting buildings on a campus or wider area, up to 60 miles apart.
- Two complete rings, secondary is for redundancy.
ATM (Asynchronous Transfer Mode)
- Can reach throughput of 10000Mbps, but more commonly used for 622mpbs or 155 mpbs.
- Small packets (cells) of fixed size. 48 bytes of data with 5 byte header
- Does not use routing like ethernet, but ATM switches (point to point connections).
- 802.11
o Up to 2mbps, FHSS/DSSS 2.4 Ghz
- 802.11a
o Up to 54mbps, OFDM, 5 Ghz
- 802.11b
o Up to 11mbps, DSSS, 2.4 Ghz
- 802.11g
o 11/54 Mbps, OFDM (backwards with 802.11a), DSSS (backwards with 802.11b)
FHSS (Frequency Hopping Spread Spectrum)
- Data transmitted on a single frequency at any given time. However, signal hops from frequency to frequency. Pattern may seem random, but actually generated by a computation known to both sender and receiver, to reduce interference from other nearby transmissions.
DSSS (Direct Sequence Spread Spectrum
- Data being transmitted is spread over multiple frequencies, allowing faster throughput.
OFDM (Orthogonal Frequency Division Multiplexing)
- Radio signal is split into smaller, multiple signals, and then transmitted at the same time, at different frequencies. Operates at 5 Ghz and signal distance is shorter.
Bluetooth
- Uses FHSSS and interferes with 802.11x
Infrared
- Up to 10-20 feet, up to 4mbps
Connectionless protocol
- Typically for data less than 1kb
- Acknowledgement of each receipt not necessary
Connection Orientated
- For larger files, uses packet sequence numbers to verify packet order and acknowledge receipt of each packet
NetBEUI
- Small networks (20-200 nodes), good error protection, connectionless and connection-orientated
- Non routable
- Uses SMB (server message block) to share resources
NetBIOS
- Application interface operating at session layer, rather than a protocl
IPX/SPX
o Win 95, Win 98 and Win NT/2000 automatically configure IPX/SPX protocol to use the frame type first received by network on boot. This works well when there is only one version of Netware running. When more than one version of Netware (different versions) is running, you may have some problems with conflicting frame types:
 An incorrect frame type may or may not see some netware servers, or unable to see any Netware servers but browse other network resources.
 To remedy this problem, use network property sheet for IPX/SPX protocol and manually select correct frame type
- IPX runs under network layer, provides connectionless services
- SPX runs under transport layer. Provides connection-orientated.
o Controls protocol error checking, windowing, flow control
- Uses two different frame types (802.2 & 802.3)
o Cannot communicate with each other
o 802.3 used by Netware 3.1x and earlier
o 802.2 used by Netware 4.x and later
NWNBLink (NetBIOS over IPX)
- Can be used to communicate and share files between systems on any windows-based network
- Fully routable protocol.
TCP/IP
- IP is unreliable connectionless protocol. Sole function of IP is to transmit TCP/IP
- TCP provides acknowledged, connection orientated, and guaranteed delivery.
o Retransmits on error
o FTP depends on TCP
- UDP (user datagram protocol)
o Designed for connectionless, unacknowledged communications.
o Uses IP as underlying protocol
o UDP adds information about source and destination socket ID’s.
o TFTP (trivial file transfer protocol) depends on UDP
Gateways
- Connects incompatible networks by translating protocols
Remote Access Protocols - SLIP (Serial Line Internet Protocol)
o Defines a sequence of characters that frame IP packets over serial line
o Originally in the 3COM UNET TCP/IP implementation
o Slow communications (less thank 19.2k)
o Lack of error detection and correction, lack of compression, inability to provide packet addressing and packet ID information.
-Remote Access Protocols PPP (Point to Point Protocol) consists of 3 main components
o Methodology for encapsulating multiprotocol datagrams
o Link Control Protocol (LCP) for establishing, configuring, testing data link connection
o Family of Network Control Protocols (NCP) for establishing, configuring different network layer protocols
 PPP supports multiple transport protocols, therefore it allows compressions, link quality monitoring, security features, error detection and correction, and encryption
-remote protocol PPTP (Point to Point Tunneling protocol)
o Allows secure communication through virtual private networks
-remote protocol RDP (Remote Desktop Protocol)
o Part of Windows NT terminal server and Windows 2000/Server 2003 terminal server
o Default port is 3389
o Operates on application layer
Security Protocols
- IPSec
o Actually a suite of protocols used to encrypt packets.
o Transport mode – only data portion of packet is encrypted, not header
 Less secure than tunnel mode
o Tunnel mode – both data and header are encrypted
-Security Protocols
L2TP (Layer 2 tunneling protocol)
o Extension to PPP
o Enhanced tunneling protocol used in VPN. Optimized to work with Ipv6 and IPSec
o Operates at Data Link of OSI layer
-Security Protocols
SSL (Secure socket layer)
o Developed by Netscape.
o A private a public key system (RSA) is used to encrypt/decrypt data
 Messages encrypted using receiver’s public key, then decrypted with receiver’s private key
Security Protocols
- WEP
o Uses a single, manually configured static key for data encryption that is shared by a client or WAP
o Part of 802.11b, operates at physical and data link layers
Security Protocols
- WPA
o More secure that WEP
o Data encryption is more secure through use of Temporal Key Integrity Protocol (TKIP)
 Keys scrambled with hashing algorithm, and integrity checking mechanism is employed.
Security Protocols
- 802.1x
o Standard that uses EAP.
o Steps involved:
 A client requests access to wireless network from an authenticator (access point)
 After request is received, changes supplicant’s client software state to unauthorized
 Authenticator then requests user ID data, which is sent to a central authentication sever
 Authentication changes supplicant’s status to authorized or unauthorized
Baseband
- Entire capacity of cable is taken up in a single transmission.
- Uses change in electric flow to represent bits of data
- Ethernet /w coaxial uses baseband
Broadband
- Communications use different frequencies to separate messages for others by using the same media at the same time
Firewire
- Each bus (port) can support up to 63 devices
- Up to 1024 buses can be linked together
- Max 15 feet distance, but can be extended with repeaters, up to 225 feet
- 4 or 6 wire for firewire 400
- 9 pin for firewire 800
- Supports asynchronous and isochronous communications
Fiber optic cable
- Supports data rates up to 46Gbps over distances of 2-25km.
- Multimode fiber (MMF)
o Uses LED’s.
o Light travels down the core in many rays
o 50 and 62.5 micron core
- Single mode fiber (SMF)
o Uses laser light (single ray)
o 9 micron size
Fiber optic connectors - FSD
o Fixed shroud device
-Fiber optic connectors ST
o Frequently used connector. Keyed BNC style
-Fiber optic connectors SC
o International standard push/pull
o Better than ST because it has both transmit/receive fibers in a single duplexed chip
-Fiber optic connectors LC
o Developed by Lucent technologies
o Small connector designed to save space
-Fiber optic connectors MTRJ
o Another small form factor connector
o Can be used with MMF or SMF
-Fiber optic connectors SMA
o Threaded connector, no longer used
Passive hub
- Takes incoming electric signals on one port and passes them onto other ports.
- Nodes see signal like a physical bus topology
Active hub
- Also repairs weak signals by resending data with proper voltage/current
- Essentially acts as a repeater
- May also resynchronize data
Switching hub
- Looks at destination hardware address and send to appropriate port
- Also can make changes to transmission speeds
Intelligent hub
- Offers more flexibility than switching hub
- No defined standard
Token Ring devices
- UTP transmission at 4 mbps
- STP transmission at 16 mbps
- Each MSAU supports up to 8 nodes
- Maximum of 12 MSAU’s per ring
- Local ring hub permits 4 node connections on one MSAU port cable
- 64-72 max nodes recommended per ring for optimal performance
- Maximum distances
o Station to MSAU – 45 m
o MSAU to MSAU – 120 m
o MSAU to repeater – 600 m
o Maximum network length – 750 m (typical cable)
o MSAU to fiber optic repeater – 1.5km
Transceiver
- Provide a connection between one media type and another without changing channel access method
- For example, transceiver can connect a 10Base5 backbone to twisted pair hub o Change in media but both are ethernet
- Transceivers referred to as media filters in token rings
Internetworking components
- Internetworking can be defined as technology and devices by which computers can communicate across different types of networks
Repeater
- Operates at physical layer of OSI
- Boosts electronic signal from one network segment to another of the same media
- In addition to amplifying signal, it also amplifies noise, which means only a limited number of repeaters can be used
o Intelligent repeaters will regenerate the digital signal, and won’t have noise amplification
- Repeaters extend baseband networks and are typically used on bus networks
- Introduces time delay which may cause time-out errors, reduced signal quality, node limitations, and network traffic not filtered
Bridges
- Operates at MAC sublayer of Data Link
- Clean signal is sent out
- Transparent to higher level protocols
- Segments connected through bridge remain part of same logical network
- Can filter traffic based on addresses. Thus, bridges can reduce traffic between segments and improve security by selecting packets that can pass
- Heterogeneous (translating) bridge
o Can connect networks of different types (such as ethernet and token ring)
- Encapsulating bridge
o A bride packages frames of one format into another
 For example, token ring frames can be encapsulated in ethernet frames and passed out into ethernet network across to another token ring network
o Encapsulating is faster than translation, but requires appropriate bridge to de-encapsulate
- Learning (transparent bridges)
o Capable of automatically ID’ing devices on segments they connect
o Listens to each of the attached cable segments and creates a table of addresses originating on each segment
- Local bridge
o When a bridge has LAN link directly on each side
- Remote bridge
o When a bridge must link a local network across a wide area segment
Spanning tree routing algorithm
- Able to communicate with other bridges and negotiate which bridge will remain in blocking mode (not forwarding packets) to prevent formation of loops
Source routing algorithm
- Found on IBM’s token ring networks
- Workstations determines the routes to other workstations with which it wants to communicate by transmitting an all routes broadcast frame that’s propagated on the network. The second station’s reply to the broadcast includes route that the original frame took. That route is taken from that point on.
Layer 2 switches
- Generally a more modern term for multiport bridge.
o Also known as data switch, or just switch.
- Operates at data link layer (just like bridges)
- Implements more advanced filtering techniques to optimize performance
- VLAN
o Computers connected to different segments appear and behave as if they’re on the same segment
o Port based grouping
 Certain ports assigned to specific VLAN. Packets kept local to VLAN