Ensuring Network Availability Flashcards
Software that reproduces text input and output for a given command shell or OS
Terminal emulator
Application protocol supporting secure tunneling and remote terminal emulation and file copy. SSH runs over TCP port 22.
Secure Shell (SSH)
Application protocol supporting insecure terminal emulation for remote host management. Runs over TCP port 23.
Telnet
Application protocol for operating remote connections to a host using a graphical interface. The protocol sends screen data from the remote host to the client and transfer mouse and keyboard input from the client to the remote host. It uses TCP port 3389.
Remote Desktop Protocol (RDP)
Application protocol allowing machines to synchronize to the same time clock that runs over UDP port 123.
Network Time Protocol (NTP)
Measurement of a value affecting system performance such as CPU or memory utilization.
Performance Metrics
Troubleshooting issue where performance for a whole network or system is constrained by the performance of a single link, devices or subsystem.
Bottleneck
Establishes the he resource utilization metrics at a point in time such as when system was first installed. This provides a comparison to measure system responsiveness layer.
Performance baseline
Device that can report environmental conditions such as temperature or chassis intrusion to a monitoring system.
Sensor
Application protocol used for monitoring and managing network devices. SNMP works over UDP ports 161 and 162 by default.
Simple Network Management Protocol (SNMP)
Application protocol and event logging format enabling different appliances and software applications to transmit logs or event records to a central server. Syslog works over UDP port 514 by default.
Syslog
Threshold for storing or forwarding an event message based on its severity index or value.
Logging level
Systems that differentiate data passing over the network that can reserve bandwidth for particular applications. A system that cannot guarantee a level of available bandwidth is often described as Class of Service (CoS)
Quality of Service (QoS)
Generally used to refer to the amount of data that can be transferred through a connection over a given period. Bandwidth more properly means the range of frequencies supported by transmission media measured in Hertz.
Bandwidth
The time it takes for a signal to reach the recipient. A video application can support a latency of about 80ms while typical latency on the internet can reach 1000ms at peak times. Latency is a particular problem for 2-way applications such as VoIP and online conferencing.
Latency
Variation in time it takes for a signal to reach the recipient. Jitter manifests itself as an inconsistent rate of packet delivery. If pack loss or delay is excessive then noticeable audio or video problems (artifacts) are experienced by users.
Jitter
Header field used to indicate a priority value for a layer 3 (IP) packet to facilitate Quality of Service (QoS) or Class of Service (CoS) scheduling.
Differentiated Services (DiffServ)
IEEE standard defining 3 but (0 to 7) class of service priority field within the 802. Class Q format.
802.1p
Appliances and or software that enable administrators to closely monitor network traffic and to manage that traffic. The primary function of this is to optimize network media throughput to get the most from the available bandwidth.
Traffics shapers
Utility used to measure bandwidth achievable over a network link
iperf
Hosted utility used to measure actual speed obtained by an Internet link to a representative server or to measure the response times of websites from different locations on the internet
Bandwidth speed tester
Cisco developed means of reporting network flow information to a structured database. Netflow allows better understanding of IP traffic flows as used by different network applications and hosts.
Netflow
Metrics recorded by a host or switch that enable monitoring of link state, resets, speed, duplex setting, utilization and error rates.
Interface statistics
Troubleshooting issue where an interface reports packet errors due to frame corruption and other factors.
Interface errors
