Comtech EF Data / Stampede
FX Series Administration Guide - Version 6.2.2
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Chapter: Overview - FX Series
Section: Single-Sided Solution
MN-FXSERIESADM6 Rev 6
1.3.3
Connection Management
(a)
Connection management removes the burden of establishing and terminating TCP
connections from the web servers, allowing the server to handle more traffic.
Stampede manages network connections in several ways to optimize the flow of data
and reduce the impact on the network, application servers and end-user devices. The
FX Series appliance maintains a consistent pool of connections between itself and the
servers. The servers are then offloaded from managing the connections, and are
isolated from inadvertent session disconnects.
(b)
The FX Series appliance limits active flows. Active flows are the number of UDP and TCP
connections that can be established concurrently between remote clients and content
servers which flow through the FX appliances. This should normally never be an issue,
but can be a problem in a denial of service attack. The FX series reports the number of
active connections in the status monitor.
(c)
With Stampede's FX Series Remote appliances working with the FX Series head-end appliance, a
persistent connection between the client and server is always maintained, even when the
browser may close and reopen a session. These sessions are also multiplexed across multiple
connections, improving throughput and response time. This persistent connection is extremely
important for AJAX and Web 2.0 applications which constantly open and close sessions as they
poll and access various Web services. Stampede eliminates this potentially network intrusive
overhead.
1.3.4
ACM QoS
The Quality of Service Function with ACM option is intended to work with modems that support ACM.
The FX Series ADC and Remote have the ability to read the current data rate from the modem, and will
adjust the output data rate to match the modem data rate. The FX Series data rate is calculated based a
per Ethernet frame basis
The FX is also designed to work with the modem in a 1:1 Redundant with fail over mode and work with
the modems when they are in a 1:1 redundant configuration.
Output Data Rate
All data rates are Ethernet frame rates. The total data rate is a parameter that can be set, or
under the optional ACM mode, can be updated dynamically and continuously from the modem in
the link.
Traffic Classification
Traffic can be classified on combinations of Protocol, VLAN, Source/Destination IP Port number,
Source/Destination subnet, MPLS labels/EXP and DSCP bits.
Classified traffic is directed into specified Queues. Queues are assigned priority. There are two
levels of Groups and a third level of Queues that can be configured. Traffic coming into the
appliance is separated by Filters into the level 1 Groups. This traffic can subsequently be
separated by Filters into a second level of Groups, and then filtered into Queues where traffic
will be released to the WAN based on the QoS and shaping rules defined.
Traffic shaping
Traffic is shaped using drain algorithms on the specified queues. Queues of equal priority are
treated in a fair-weighted manner. Connections within a specified Queue are also treated in a
fair-weighted manner.
