Ethan Banks On productivity.

OECG – Chapter 6 Definitions


passive mode FTP – an FTP mode where the server dynamically allocates a port and the client opens a socket to that port from a port he dynamically allocated.

active mode FTP – an FTP mode where the client dynamically allocates a port, and the server opens a socket to that port from his source port of 20.

SNMP agent – the agent running on a device that responds to SNMP queries against his MIB variables. Sends traps.
SNMP manager – a device that queries the MIB of an SNMP agent. Accepts traps.
Get – an SNMP command to retrieve a single MIB variable.

GetNext – an SNMP command to retrieve the next MIB variable after the one previously requested.

MRTT – measured round-trip time. A timer maintained by a TCP sender. If this timer expires, unacknowledged data will be resent.

GetBulk – an SNMP command that gets a whole lot of data at a whack, without having to ask for one variable at a time.

MIB-I – a standard management information base as defined in the SNMP v1 specification. RFC 1158.
MIB-II – a standard management information base as defined in the SNMP v2 specification. RFC 1213.
Response – the standard method an SNMP agent responses to SNMP manager get, getbulk, getnext and set requests.

trap – unsolicited SNMP information sent from an agent to a manager

set – an SNMP manager telling an SNMP agent what to set a particular MIB variable to

inform – 2 SNMP managers exchanging MIB data

SMI – structure of management information. Defines the syntax for creating a MIB.
MIB – management information base

CWND – congestion window, used by a TCP sender to send data without losing packets.

SSThresh – slow start threshold, half the value of the original CWND used when packet loss was first experienced

window – the amount of data in bytes that a receiver will accept before sending an acknowledgment

Slow Start – the algorithm used to exponentially slide the window open during successful TCP exchanges

Congestion avoidance – the algorithm used to linearly slide the window open after the SSThresh is reached

MSS – maximum segment size. The largest size you can make a packet, minus the TCP and IP headers of a TCP packet. A TCP host must support an MSS of at least 536.
MTU – maximum transmission unit. The largest size you can make a packet, including the TCP and IP headers. IP hosts must accept an MTU of at least 576.
socket – a formed connection between 2 TCP/IP hosts.

TCP code bits – a field of 6 bits or flags that can be set to identify important packet characteristics.

TCP flags – PSH, URG, SYN and ACK. (Same as code bits.)
Receiver’s advertised window – what the receiver first advertises to the sender he’ll accept for data before acknowledging.

MIB walk – what “getnext” and “getbulk” are doing – walking the MIB tree is a way to discover all the possible variables you can query without actually knowing what they are.

By Ethan Banks
Ethan Banks On productivity.

You probably know Ethan Banks because he writes & podcasts about IT. For example, he co-authored "Computer Networks Problems & Solutions" with Russ White.

This site is Ethan on productivity--not tech so much.

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