Blue Coat Systems Blue Coat Systems SG Appliance, SGOS Version 5.2.2 manual 103

Appendix A: Glossary

statistics	Every Blue Coat appliance keeps statistics of the appliance hardware and the objects
	it stores. You can review the general summary, the volume, resources allocated, cache
	efficiency, cached contents, and custom URLs generated by the appliance for various
	kinds of logs. You can also check the event viewer for every event that occurred since
	the appliance booted.
stream	A flow of a single type of data, measured in kilobits per second (Kbps). A stream
	could be the sound track to a music video, for example.
SurfControl log type	A proprietary log type that is compatible with the SurfControl reporter tool. The
	SurfControl log format includes fully-qualified usernames when an NTLM realm
	provides authentication. The simple name is used for all other realm types.
syslog	An event-monitoring scheme that is especially popular in Unix environments. Most
	clients using Syslog have multiple devices sending messages to a single Syslog
	daemon. This allows viewing a single chronological event log of all of the devices
	assigned to the Syslog daemon. The Syslog format is: “Date Time Hostname Event.”
system cache	The software cache on the appliance. When you clear the cache, all objects in the
	cache are set to expired. The objects are not immediately removed from memory or
	disk, but a subsequent request for any object requested is retrieved from the origin
	content server before it is served.
T
time-to-live (TTL) value	Used in any situation where an expiration time is needed. For example, you do not
	want authentication to last beyond the current session and also want a failed
	command to time out instead of hanging the box forever.
traffic flow	Also referred to as flow. A set of packets belonging to the same TCP/UDP connection
(bandwidth gain)	that terminate at, originate at, or flow through the SG appliance. A single request
	from a client involves two separate connections. One of them is from the client to the
	SG appliance, and the other is from the SG appliance to the OCS. Within each of
	these connections, traffic flows in two directions—in one direction, packets flow out
	of the SG appliance (outbound traffic), and in the other direction, packets flow into
	the SG (inbound traffic). Connections can come from the client or the server. Thus,
	traffic can be classified into one of four types:
	•	Server inbound
	•	Server outbound
	•	Client inbound
	•	Client outbound
	These four traffic flows represent each of the four combinations described above.
	Each flow represents a single direction from a single connection.
transmission control	TCP, when used in conjunction with IP (Internet Protocol) enables users to send data,
protocol (TCP)	in the form of message units called packets, between computers over the Internet.
	TCP is responsible for tracking and handling, and reassembly of the packets; IP is
	responsible for packet delivery.
transparent proxy	A configuration in which traffic is redirected to the SG appliance without the
	knowledge of the client browser. No configuration is required on the browser, but

network configuration, such as an L4 switch or a WCCP-compliant router, is required.

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