Product Documentation

Glossary

Jan 28, 2011

Text for Glossary

| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W |

A

Accelerated bridge
Two ports on a bypass Ethernet card that are used as a two-port Ethernet bridge, performing inline-mode acceleration.
Accelerated Pair A (apA)
The first accelerated bridge on a CloudBridge appliance.
Accelerated Pair B (apB)
The second accelerated bridge on a CloudBridge appliance
Accelerated port
One of the two ports on an accelerated bridge.
Acceleration
The process of making network operations finish more quickly.
Acceleration Modes
Different modes of accelerated TCP. Two CloudBridge acceleration modes are supported: hardboost and softboost.
Acceleration policy
An entity specifying how to accelerate a given connection: no acceleration, flow-control only, memory based compression, disk based compression.
Accelerator
Something that accelerates IP traffic: namely, a CloudBridge appliance or virtual machine. In the case of the CloudBridge 4000/5000, this applies to the management (broker) instance and the accelerator instances taken as a unit.
Accelerator instance
Refers to an accelerator in the form of a virtual machine. Such accelerators are used in the CloudBridge VPX, 400, 800, 2000, 3000, 4000 and 5000.
Appliance
A NetScaler or CloudBridge hardware product.
Application classifier
The part of the traffic shaper that determines which application a given data stream belongs to.
Asymmetric routing
A routing configuration that does not support acceleration unless additional steps are taken. For acceleration to function properly, all packets for a given connection, in both directions, must pass through the appliance. If all packets for a given connection pass over the same WAN link, there is no asymmetry. If the packets for a given connection are distributed over more than one WAN link, there is asymmetry.
Autodetection
The process of detecting an acceleration partner through the presence of characteristic IP or TCP header fields.
Auto-negotiation
The process by which two appliances decide on the data rate and compression method to use for communication with each other.
Auto-optimization
Zero-configuration optimization based on CloudBridge auto-detection and auto-negotiation.
Auxiliary port
One of the motherboard ports on a CloudBridge appliance

B

Branch office
An office smaller than a datacenter or a regional office, generally with 10 Mbps of WAN capacity or less, and assumed to have no IT personnel on site.
Branch Repeater
A CloudBridge appliance intended only for use in branch offices.
Bypass card
An Ethernet adapter with bypass (fail-to-wire) capability between pairs of ports
Bypass mode
CloudBridge operational mode that does not accelerate traffic. Either the bypass relay is closed on the accelerated bridge, bypassing the rest of the appliance, or acceleration is disabled, which leaves bridging active.

C

Caching
The act of saving a copy of data for possible future use.
CloudBridge
A Citrix product that accelerates IP data transmission between two locations or between a location and a cloud. Available as a physical appliance or as a virtual instance on a CloudBridge 4000/5000 appliance. Not to be confused with the old CloudBridge IPSec tunnel (now called CloudBridge Connector), which is an unrelated NetScaler feature.
CloudBridge 2000/3000
Mid-range CloudBridge appliances.
CloudBridge 4000/5000
High-end CloudBridge appliances, characterized by multiple accelerator instances.
CloudBridge 600 series
The current name for the former Branch Repeater 100, 200, and 300 appliances.
CloudBridge 700 series
The current name for the former Branch Repeater with Windows Server 100, 200, and 300 appliances.
CloudBridge accelerator
Same as "accelerator."
CloudBridge connector
A NetScaler feature that creates an IPSec tunnel to another NetScaler. Unrelated to the CloudBridge accelerator.
CloudBridge partner
The CloudBridge unit at the other end of the link. Acceleration requires a CloudBridge unit at each end of the link. The accelerator at the remote end of the link is the parter of the accelerator at the local end of the link.
CloudBridge Plug-in
An accelerator in the form of a Windows service. Provides client-side but not server-side acceleration. Intended largely for laptops that use a VPN to connect remotely to a corporate network.
CloudBridge VPX
A CloudBridge instance packaged as a downloadable product for use in customer servers.
Common Internet File System (CIFS)
The native protocol of Microsoft Windows for network file-system services.
Compression
The process of reducing the data stream by encoding it in a way that removes redundancy.
Compression engine
The portion of the accelerator that performs compression and decompression.
Compression ratio
The ratio of uncompressed payload to compressed payload.
Configuration synchronization
The act of copying appliance configuration to relevant partners: high availability partners, group mode partners, or, in a CloudBridge 4000/5000 appliance, other accelerator instances.
Connection termination
One end of a connection. Connections terminate at the client and the server. If a proxy is used, the connection also terminates at the proxy.
Connector tunnel
The IPSec tunnel created by the NetScaler CloudBridge Connector feature.
Crypto license
A CloudBridge license that enables secure peering and features that depend on secure peering.

D

Datacenter
A site with servers and full-time IT personnel.
Device
A hardware product, usually from a company other than Citrix. For the Citrix Command Center product, device refers to any entity being managed by Command Center.
Disk based compression
Compression that saves the data stream to disk, allowing much larger compression histories and compression histories that are persistent across reboots.

E

End-around packet

A packet that bypasses the appliance by taking another path.

F

Factory reset
A command to restore an appliance to near-factory state, destroying its previous configuration and taking it off the network. Not to be confused with "reset to defaults."
Failover
The process by which one appliance in a high-availability pair takes control when the other appliance seems to have failed.
Fail-to-wire (FTW)
Ethernet bypass, where loss of power or functionality causes the two ports of an Ethernet bridge to be connected via a relay
Fast Ethernet
100 Mbps Ethernet.
forwarding modes
Methods of moving packets between the appliance and the network (for example, inline, WCCP, and virtual inline).

G

Generic Routing Encapsulation (GRE)
An IP protocol.
Group mode
A method of getting two appliances in two nearby datacenters with two separate links to behave as if they were a single appliance. Rarely used.

H

Hardboost mode
An acceleration mode that uses rate-based TCP sender and rate negotiation with the partner appliance to decide the speed at which to send traffic. Self-clocking, slow-start, and congestion avoidance algorithms are not used.
Health monitoring
Any method that detects whether a partner device is operational.
Heartbeat
A packet stream between the members of an HA pair, loss of which implies failure.
High availability mode
Active/passive mode in which if one appliance fails, the other takes its place

I

Inline mode
The accelerator's bridged mode, in which the accelerator masquerades as an Ethernet switch, performing acceleration transparently to the customer's routing infrastructure.
IPSec tunnel
An encrypted, authenticated packet tunnel conforming to the IPSec standard.

J

Jitter
Variability in latency from one packet to another within the same data stream.

K

Kerberos
A computer network authentication protocol.

L

L2 mode
In WCCP, connections that use simple routing instead of GRE encapsulation.
Latency
Packet delay, usually stated in terms of round-trip time (RTT).
Link definitions
The user-defined rules that distinguish LAN from WAN traffic, and, if multiple WANs are present, distinguishe one WAN's traffic from another.
Link-down propagation
A technique that, when Ethernet carrier is lost on one port, drops Ethernet carrier on the other ports so the router can detect0 that connectivity was lost on the far side of the appliance.
Lossless Flow Control
A technique of controlling traffic rates without the need to drop packets from connections that are sending too quickly.

M

Management IP address
The main IP address for an accelerated bridge.
Management service
A virtual machine that provides maintenance features on appliances, such as the CloudBridge 2000, that provide the accelerator as a virtual machine.
Management subnet
A subnet that is used for management but not for accelerated data.
Memory based compression
Compression that does not save the data stream to disk.
Messaging Application Programming Interface (MAPI)
The native protocol of Microsoft Exchange and Microsoft Office.

N

NetScaler instance
The NetScaler VPX instance on a CloudBridge 4000/5000 appliance.

O

One-arm mode
A non-bridged mode: WCCP, virtual inline, or redirector.
Optimization
Used as a synonym for "acceleration."

P

Pass-through traffic
Traffic that passes through the accelerator but is not accelerated. Includes non-TCP traffic.
Payload
The portion of a packet that is not the packet header.
Port affinity
When traffic is prevented from migrating from one port to another, it is said to have an affinity to a particular port.
Primary appliance
In high-availability, the active appliance.
Primary port
One of the motherboard ports on a CloudBridge appliance
Private traffic subnet
An internal subnet, on the CloudBridge 4000/5000, that is not directly accessible to the outside world, and carries accelerated traffic between the accelerator instances and the NetScaler instance.

Q

Quality of service (QoS)
Quality of service. An industry-standard term with essentially the same meaning as traffic shaping. (Only the latter term is used in CloudBridge documentation.)

R

Redirector mode
A mode that allows the CloudBridge appliance to act as an explicit proxy for CloudBridge Plug-in connections.
Repeater
An older-model CloudBridge appliance, intended for use in datacenters. Only the 8500 and 8800 model Repeater appliances are currently available.
Reset to default
A command that restores most parameters on an appliance to their default (factory) state, while leaving licensing and IP addresses intact. Intended to be non-destructive.
Return to Ethernet Sender
A routing technique by which returning packets are sent back to their origin by simply reversing their source and destination Ethernet MAC addresses.

S

SCPS
Space Communications Protocol Specification, a variation of the TCP protocol. Used for some satellite communications.
Secondary appliance
In high availability, the standby appliance.
Secure peering
Use of a secure tunnel, between two accelerators, that encrypts all accelerated data between them (but not unaccelerated data).
Send to Gateway
Normal routing, by which packets that require routing are sent to the default gateway for that interface.
Service classes
Connection categories. The accelerator divides connections into service classes based on the connection's application. This in turn determines compression type and acceleration policy.
Signalling IP address
A virtual IP address used for secure peering or the CloudBridge Plug-in.
Softboost mode
An acceleration mode siimilar to standard TCP, but with additional features such as rate-based sending and advanced retransmission algorithms.
Speculative retransmissions
Packet retransmissions that are sent before an ordinary network stack would send them, because they might have been lost and the retransmission overhead is preferable to the delay of waiting for acknowledgement.
SSL split proxy
One of two basic configurations of CloudBridge SSL compression, chosen for compatibility with the accelerated application. The other is SSL transparent proxy.
SSL transparent proxy
One of two basic configurations of CloudBridge SSL compression, chosen for compatibility with the accelerated application. The other is SSL split proxy.
SYN packet
The initial (synchronization) packets of a TCP connection.

T

Traffic interface
An interface that carries accelerated data.
Traffic shaping policy
A weighted priority, maximum bandwidth, and other traffic-related specifications.
Traffic-shaping
Prioritized injection of data packets onto the WAN, or prioritized processing of data packets received from the WAN. Either way, the data rate is constrained to be no faster than the specified bandwidth limit.
Traffic-shaping engine
The traffic shaper portion of the accelerator
Transparent mode
A mode that allows the CloudBridge appliance to act as an intercepting proxy for CloudBridge Plug-in connections.
Transparent operation
The ability to provide acceleration without reconfiguring any servers, clients, or (usually) routers in the network.

U

Unaccelerated connection
Any TCP connection that does not receive CloudBridge acceleration.
Update bundle
An archive containing all the files for all the VMs in a virtualized system such as the CloudBridge 2000/3000/4000/5000.

V

Video caching
The act of saving a copy of a video data stream for possible future use.
Virtual gateway
Another name for an accelerator, in its role of introducing bandwidth-limited fair queuing to the traffic passing through it.
Virtual inline mode
A forwarding mode that uses a dedicated router port and policy based routing rules on the router.
Virtual IP
An additional IP address declared on an interface that already has an IP address.
VLAN tagging
The act of assigning a VLAN to an interface or data stream.
VLAN trunking
The use of VLANs, and often multiple VLANs, on the same Ethernet segment.

W

WCCP mode
A forwarding mode where the appliance uses the WCCP protocol to communicate with the router.
Weighted fair queuing
A queuing discipline in which each connection gets its fair share of the link bandwidth, but not all connections have the same priority.

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