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Network Glossary

Network terms

CSMA/CD Listen before send, listen while I send, probablistic
CSMA/CA Detect collision and resend packets, probabilistic
10BaseT Standard that uses UTP cable, RJ-45 connectors, transfers up to 10Mbps. Economical / easy to install. Max 330 ft
10Base2 Standard that uses Coaxial / BNC connectors, up to 10Mbps. Max 610.5 ft
10Base5 Original Ethernet using coaxial cable
100BaseTX Standard that uses UTP cable, RJ-45 connectors, transfers up to 100Mbps
100BaseFX IEEE spec for fiber, up to 100 Mbps
802.3 / Ethernet Access method used to connect computers, uses physical cables. Link / physical layer protocol
1000BaseCX IEEE spec for gigabit Ethernet for short-haul copper twinax
1000BaseLX IEEE spec for gigabit Ethernet HDX/FDX fiber at 850nm wavelength
1000BaseSX IEEE spec for gigabit Ethernet HDX/FDX fiber at 1300nm wavelength
802.x Generic designation for IEEE subcommittees responsible for developing specifications for LANs and MANs
IEEE Institute of Electrical and Electronics Engineers
802.3ae Defines a version of Ethernet with a nominal data rate of 10Gbps
802.3af Defines a spec for PoE supporting up to 13.5 watts
802.11x (a/b/d/g/n/ac) IEEE subcommittees responsible for WLAN technologies
802.11a 5.75 Ghz, up to 54Mbps, realistically 20-25Mbps. 150ft. 4, 8, or more channels depending on the country. 40mW, 2.5in band width. 23 channels (12 non-overlapping)
802.11b 2.4Ghz, max 11Mbps, usually 4-6Mbps. 250ft. Interferes with Bluetooth, cordless phones, microwaves, TVs... 3 non-overlapping channels Channels 1, 6, 11 in US 1, 7 13 in EUR 100mW
802.11e QoS support for LAN applications
Guided media Signal is contained within the cable
Unguided media Wireless
UTP Unshielded twisted pair, inexpensive, easy to install Hard to splice, limited distance, affected by EMI
STP Shielded twisted pair
Baseband 1 signal over the cable (ethernet)
Broadband Uses multiplexing to have multiple signals over 1 line (cell phone - internet, voice, gps)
Multimode (fiber) Short to medium distance, 10-1000Mb ethernet over 62.5 micron fiber, uses LEDs
Single mode fiber Long haul comms. (EX. SONET for voice / data transport at speeds up to 140Gbps (on each pair), 10Gb Ethernet, 9 micron core, uses lasers.
Fiber Optics (FO) High-speed, no EMI, can multiplex many channels over 1 cable. No sparks / danger of electrical shock, signal loss much less than metallic media Expensive, difficult to splice
Attenuation Break up of signal over distance
Optical power meter Used to optimize alignment for Maximum Link Robustness, shows signal strength in dBs (decibles)
Copper Inexpensive, ubiquitous, High-speed Baseband, attenuation, EMI, electrical hazard
Coaxial High-speed, broadband, inexpensive EMI, attenuation, electrical hazard
Microwave Up to 45Mbps, cost effective, easy to install / implement licensed freq Limited to LoS, interference from other radio waves, adversely affected by weather
Satellite Comms High transmission rates, simultaneous comms to Earth stations, cost is not distant dependent. Propagation delay .5 to .7 sec, sensitive to sunspots and weather, vulnerable to eavesdropping / interception, interference from microwave, realigning
asynch Asynchronous protocol, data link protocol 1 char / 8-bits at a time
bisynch binary synchronous protocol, data link protocol 1 block (size dependent on media) at a time
protocol rules which govern the way in which computing/network devices communicate
duplicity / duplex simplex - one way communications (listen only / send only) half-duplex - listen or receive but not both at the same time full-duplex - listen and receive at the same time
SDLC Synchronous Data Link Control
HDLC High Level Data Link Control Can send 1-128 frames at the same time, full duplex base of all protocols
block size high failure rate = more retransmissions = small blocks (unreliable media) low failure rate = less retransmissions = large blocks (reliable media)
MTU Maximum Transmission Unit (max frame size) 1500 MTU = 1500 bytes frame size
Data Link Protocol main function Synchronization Framing Control Error Correction
EBCDIC 2^8 ability to represent more special chars than ASCII
Parity bit Used for error checking, odd or even / 0 or 1 depending on if bits sent add up to an even or odd number. 8th bit in the byte
CRC Cyclic Redundancy Check - algorithm for error checking, generates checksum for compare by receiving machine. If receiving machine's checksum doesn't match, it sends a NACK
NAK Negative ACK
Maxout Maximum outstanding frames, max amount of frames in limbo (can be transmitted before ACK is received), unreliable media = set high maxout to get as much across as possible at a time (for synch at endpoint), reliable / fast = low maxout, not overwhelm endp
Piggybacking ACKs Send 1 ACK for multiple frames at a time
Synchronization (data link) maintain synch of frames between sending and receiving
framing (data link) mark beginning and end of each transmission frame
control (data link) sending station capable of identifying receiving station
error detection (data link) error detection and recovery
802.3 af / at PoE spec from IEEE
LAN privately owned geographically limited shared media
*SAN Storage Area Network [EMC] for backing up servers / datacenters without introducing a lot of traffic on the regular LAN
*LLC Logical Link Control Protocol - error detection, framing of low level metadata, interface to higher layer protocols.
MAC Media Access Control, hardware addressing. Assembly of data into a frame with address and error detection fields. Controlled by IEEE
Token Ring Token is passed around, everyone guaranteed access to the network
Bus Topology, all connect to an ethernet turnk
Token Bus 1 cable, multiple NICs, uses Token protocol / access method. Generally used in robotics.
Access method CSMA/CD (probablistic) CSMA/CA Token (deterministic), separate from the topology
Star topology Advantages: centralized control, network management visibility, easier to troubleshoot Disadvantages: Expensive investment in a cable, single point of failure
Ethernet maximum frame size 1500, set MTU to 1376-1380 to provide room for encryption bits. If not, frames will be larger than 1500 bytes and will fragment, causing higher overhead.
Ethernet MAC Address Frame Formats v Ethernet DIX v2 format See slides TYPE v LENGTH
Broadcast Frames go to everyone [printer, network discovery, arp, collision announcement]
Multicast Sent to specific hosts that are subscribed to receive
Unicast Frame goes to a single MAC address
802.11g/b 2.4GHz, up to 54Mbps, 3 non-overlapping channels. 100mW, 6 inches (band width), 150ft diameter cell size
OFDM Orthogonal Frequency-Division Multiplexing modulation
CCK Complementary Code Keying modulation
PBCC Packet Binary Convolutional Coding modulation
802.11i WLAN security standard, describes encryption transmission of data between a and b WLANs. TKIP, AES, channel selection, roaming, transmit power control
802.11k Improve traffic distribution, checks if AP w/ strongest signal is at capacity and connects to another AP if so.
802.11n a/g compatible, 2.4 or 5.75 GHz, multiple-input multiple-output, error detection and correction. Spacial multiplexing - 2 Transmit & 1 Receive antenna
MIMO Multiple Input Multiple Output, Spatial multiplexing
802.15 Standard for WPANs, .1 is based on the Bluetooth spec, .2 working on interference in the 2.4GHz band, .3 wants up to 55Mbps up to 10m, .4 ZIGBEE
Guided v Unguided media Wireless v Cables
EIA/TIA Standards Ethernet wire color codes T568A and B for CAT .5
UTP CAT 3 100 Ohm, UL Level III
UTP CAT 4 100 Ohm Low Loss UL Level IV
UTP CAT 5 / 6 100 Ohm Extended Frequency UL Level V
Solid CAT 5 v Stranded CAT 5 Solid = rigid = long distance, Stranded = flexible = patch cable 10 to 100 Mbps Ethernet, up to 100MHz
CAT5e Up to 1000Mbps, suitable for Gig. Ethernet, less near-end crosstalk
NEXT Near End Crosstalk
CAT 6 Incorporates a longitudinal separator that isolates each pair from the others. Supports 10Gb Ethernet, up to 250MHz
Plenum Cabling rated for use in air ducts that does not emit toxic fumes when melted
Geosynchronous orbit turns at same orbit as Earth, 22,500 miles up, requires 3 to 4 degree space between geosync. satellites to prevent interference. Must be realigned every month.
Transponder Core of satellite transmission system, usually 24-48 transponder spaces for sending and receiving data, each divided into subchannels. Receives weak signal from Earth, amplifies it, changes freq, and retransmits. Send and receive on different freqs.
Footprint Area of the earth where the signal may be received, several hundred to thousand km. Narrower footprints = stronger signal. Ku-band satellites tend to be narrower than C-band
Modulo Number of frames that can be outstanding before sender must wait for an ACK from receiving stations
Wireless - RF / Infrared Speed, cost effective, easy to install /implement Distance / cell size, interference, transmission insecure
Free Space Optics (FSO) + Beams only a few m in diameter at a km, close spacing of links w/o interference, secure, efficient energy, more than 8km possible Rapid installation w/o construction, direct connection to end user, bypasses building owner, no interference, unlicensed
FSO - Environmental factors, need clear and calculated LoS
Multiplexing In telecommunications and computer networks, multiplexing (sometimes contracted to muxing) is a method by which multiple analog message signals or digital data streams are combined into one signal over a shared medium.
Analog Waves, continuous
Digital Discrete, 1s and 0s
TDM Time Division Multiplexing, each device has a time slot to send, if it has nothing to send it's wasted bandwidth. Aggregate line speed has to be at least equal to aggregate of all connecting line speeds
STDM Statistical Time Division Multiplexing, aggregate line speed is less than aggregate speeds of each line that connects to it.
MUX Multiplexer
Polling Asks every device if they have something to send, one at a time.
DWDM Dense Wave Division Multiplexing - separate the signal using prisms, OC-192 can support 40Gb. 1,000 different colors over 1 line at the same time, each color has a 40Gb link
Contention methods Allow sharing of media, CSMA/CD or CA, polling, token passing
Token passing Talking stick method, free or taken tokens, devices can fill free tokens with what they want to send and pass it on, deterministic
NIC Addressing, translates from network (serial) to CPU (parallel) and back
Intelligent wire hubs Port is occupied or busy / transmits data
ARIN American Registry for Internet Numbers (ARIN) - allocated IP addresses
IANA The Internet Assigned Numbers Authority (IANA) is responsible for the global coordination of the DNS Root, IP addressing, and other Internet protocol resources.
ICANN The Internet Corporation for Assigned Names and Numbers (ICANN /ˈaɪkæn/ eye-kan) is a nonprofit organization that is responsible for coordinating the maintenance and methodologies of several databases...
DIX Digital Intel Xerox, proprietary Ethernet
Licensed Freq Leased from the FCC
IP Address v4 Dotted decimal system, 32 bits, 4 octets
Class A -
Class B -
Class C -
IETF Internet Engineering Task Force - implement new protocols / modifications
RFC 1917 / 1918 Introduced ability to have public / private IP ranges
Class D -
Class E -
IP packet [version][IHL][Type-of-service][Total length] ...
Subnet mask 255 determines network portion of ip address, rest is host portion
Analog has inherent noise, when re-amplified, noise is also re-amplified. Digital will always have more throughput.
Hub Fastest, nothing to process, just re-broadcast. Layer 1 device 1 collision domain
Flooding How routing device build ARP / bridge tables for routing between network initially
Bridge connect layer 2 networks together, forwards, not routes Forwards all frames based on learned topology Can propagate broadcast storms
Switch connect layer 2 devices together CAM table (instead of bridge table)
Spanning Tree Protocol Block loops in bridged / switched networks, useful on intermediate nodes - devices that pass traffic
Root bridge determined by lowest MAC address (or configurable), put it in the middle of topology in order for low amount of recalculating paths
Layer 2 v Layer 3 broadcast storm Affects everyone v Affects local
Adjacenty Router next to you
Route table Only network addresses to port numbers, number of route tables = number of interfaces x number of supported protocols (AppleTalk, DECnet, Novel...)
ARP table Only IP (host) addresses to MAC Addresses
RIP Routing Information Protocol Distance vector, based on vectors (number of hops) between routes.
(E)IGRP (Enhanced) Interior Gateway Routing Protocol Two routers within an autonomous system are called interior
Autonomous system (AS) All devices under a single administrative control
IGP Interior Gateway Protocol used for routing within networks within an AS
OSPF Open Shortest Path First
BGP Peering Point (NAP) Where all internet peering connects, what ISPs use to talk to other ISPs
Routing algorithm metrics bandwidth delay smallest MTU (Max size transmission unit) reliability load hops cost (of a hop)
Router Redundancy Clients with Host Router Discovery Protocol enabled will choose the best gateway / whichever one is up or best based on metric
Static routes For routers that do not speak common protocols
Asymmetrical routing Can be horrible slow, mismatch between speeds can kill connections
BGP routing used for exterior routing
Default paths Hosts have default gateways Routers have default networks
Distance vector v hop count v link state table (updates every 30 sec) v decrementing hops v up / down Convergence (link recovery) is faster with link state change
latency any kind of delay
jitter variation in latency
components of response time (server / client) processor, utilization, network interface (speed / drivers), RAM, protocol
(network) autodiscovery generally not a good idea in huge environments, operates with broadcast, can disable a network
2.4GHz channels 1, 6, 11 to avoid co-channel interference
WPAN - Wireless Personal Area Networks Ex. Nike shoes sensor communicated with a Fitbit
Different wireless protocols at the physical layer for signal FHSS, DSSS, HR DSSS, OFDM, MIMO, OFDM
WLAN Service Set Logical grouping of devices
SSID - Service Set Identifier Network ID
IBSS - Independent Basic Service Set adhoc (No AP), does have SSID, must be configured
BSS Requires AP (only one)
ESS (Extended) Multiple APs, same SSID - 1 subnet, roaming layer 2
Co-Channel Interference Interference on overlapping channels
802.11 Beacon clients send probe request frame on every channel it an see containing info about the client station
Lower freq = longer dist 2.4 has longer distance
WLAN Controller (LWAPP AP) Dynamic APs, expand and contract cell size based on ambient RF. Controller view channel and power of each AP connected to it and looks at what signals each AP sees from the other APs. Adjusts power and cell size for efficiency
DHCP Option 43 Used by WLAN Controllers to configure connected APs (like DHCP) such as power and channel per AP
Power level how far you can transmit v. interference introduced
Antennas Coverage pattern / coverage distance. Omni - generates circular pattern, has 'doughnut effect' of being too close / in the eye of the signal.
5.75 GHz 12 channels, smaller channel size
Channel Bonding Combining channels as pairs, combining their sub-frequencies, for faster speeds (more bandwidth), can only combine adjacent frequencies, in patterns, keep adjacent frequencies in non-adjacent cells
AIT Automation Identification Technologies (umbrella of RFID), bar codes, matrix codes
RFID Use RF to transmit data, improve error recovery, increase velocity, reduce process errors. Push data to data warehouse for central access and management. Logistics, tracking, identification
Backscatter (passive) RF pattern that emanates from a chip
Active RFID Have a battery, 300ft range, 802.11 has a MAC address, great for triangulation - tracking things not near readers. Could be used to track legitimate (tagged) versus rogue (untagged) devices
Passive RFID 900MHz, 3m range, powered by RF from reader
EPC tag Can be read by anyone, can read / generate any frequency. Different countries operate RFID at different freq. so EPC reader is essential
Enterprise WLAN AP Can double as a RFID reader
RSSI Relative Signal Strength Indicator
TDO Time Difference of Arrival
Exciter Foreces tags in a specific range to chirp (their MAC), location reported. Helps save battery life by activating RFID when needed.
SNMP pt 1 an IP standard for managing devices on TCP/IP networks. Devices that typically support SNMP include routers, switches, servers, workstations, printers etc.
SNMP pt 2 is used in net. mgmt systems (NMS) to monitor devices for conditions that require admin attention, it consists of a set of standards for network management, including an application layer protocol, a database schema and a set of data objects (MIBs)
SNMP pt 3 An SNMP managed network consists of three key components: managed devices, agents, and network-management systems (NMSs).
Managed device A managed device is a network node that contains an SNMP agent and resides on a managed network. Managed devices collect and store management information and make this information available to NMSs using SNMP.
MIB A Management Information Base (MIB) is a collection of information that is organized hierarchically. MIBs are accessed using a network-management protocol such as SNMP. They are comprised of managed objects and are identified by object identifiers.
Managed object A managed object (sometimes called a MIB object, an object, or a MIB) is one of any number of specific characteristics of a managed device. Managed objects are comprised of one or more object instances, which are essentially variables.
Managed objects pt 2 Two types of managed objects exist: scalar and tabular. Scalar objects define a single object instance. Tabular objects define multiple related object instances that are grouped together in MIB tables.
Managed device commands Managed devices are monitored and controlled using four basic SNMP commands: read, write, trap, and traversal operations.
spectrum analyzer Analyzing freqs that others are using, signal strengths.
Distributed application troubleshooting tracert, ping, spectrum analysis / wireless survey, protocol sniffers
Switch Each port is it's own collision domain, devices still listen for uni, multi, and broadcast traffic. Bridge table full of MAC addresses to port mappings, bridge / switch topology. No ACL for performance on layer 2.
FastForward Low latency, no error checking - fast!
FragmentFree low latency, checks for colisions
Store and Forward High latency, full error checking
VLAN Identification Using IEEE 802.1Q Unique ID in the header of each frame for what VLAN the frame belongs to
LAN Switch & troubleshooting Hard to t-shoot between VLANS, can only see traffic on own VLAN
Port mirroring Configure the switch to monitor all ports, span all ports - good for IDS, good for network visibility, good for attackers
Blocking v non-blocking LAN switches Blocking - all interfaces are 1GB but backplane speed is 1.5GB. Not giving wire speed for every port as advertised.
VLAN Broadcast domain
QoS Traffic types Best effort traffic - text, graphics = bursty, intolerant of errors Interactive Real Time Prioritize UDP(real time services) over TCP
802.1X Uses X.509 certificates to assign users to VLANs that they are assigned to originally, prevents users from plugging into the wrong VLAN
VLAN tag number in MAC frame that distinguishes what VLAN a frame belongs to, headers added to MAC frame that identify what VLAN traffic is coming from / going to
VLAN trunk Connects network devices, allows multiple VLANS to connect.
Use of MIB Collect information on AP connections, etc.
QoS Allows for prioritization of traffic to avoid latency situations
AS in routing protocols -under single admin control, everyone chooses the same AS number and can exchange route info within their AS
AAAA Net Security Policy Access, Authentication, Authorization, Audit: control physical access, knowing you are who I think you are, limiting access to specific resources, maintaining logs of unauthorized access attempts.
Session persistance Session doesn't timeout
Why are networks important to security All security devices collect, monitor, analyze, or block network traffic
Encryption != Secure connection What about data sent that is malicious and encrypted
LAN MAC layer protocols == frames, layer 2
Flooding in transparent learning bridge First time building bridge table, flood traffic out every interface to construct table by noting where responses come from and on what ports
IP aggregation - variable lane subnet masking (advanced subnetting) For backbone / links - use small subnet designations for links and large subnets for nodes. Aggregation = combine subnets to make one big one.
Link state metrics can be hops, utilization, bandwidth, etc. up to 7 etrics
Spanning tree eliminates redundant links between layer 2 devices (loops)
CDN (akami) Caches stuff locally at all ISPs for speedy retrieval of content
Local and global load balancer Multiple instances of the same application running (locally at the same datacenter) or replicated at another datacenter somewhere else (for redundancy / content delivery)
Net Mgmt System NMS collects data from the agent by collecting the MIB
MIB database of info on networked devices
Aggressive roaming v non-agressive Limited RF v a lot of RF
Security perimiter All devices that do analysis, collection, etc.
X.509 certificates Digital certificates used for MFA to access a network
Created by: cartmansav