Technical data

68 Brocade ServerIron ADX Advanced Server Load Balancing Guide
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Other transparent cache switching options
2
NOTE
You may need to set the maximum connections parameter for the remaining cache servers,
especially if the servers already run at a high percentage of their capacity when all cache
servers are available. Refer to “Configuring the maximum connections for a cache server” on
page 64.
Forceful shutdown on cache servers
SLB and TCS allow the graceful shutdown of servers and services. By default, when a service is
disabled or deleted, the ServerIron ADX does not send new connections to the real servers for that
service. However, the ServerIron ADX does allow existing connections to complete normally,
however long that may take.
You can use the force shutdown option (sometimes called the force delete option) to force the
existing connections to be terminated within two minutes.
NOTE
If you disable or delete a service, do not enter an additional command to reverse the command you
used to disable or delete the service while the server is in graceful shutdown.
NOTE
Refer to Table 10 for important information about shutting down services or servers.
Suppose you have unbound the Telnet service on real server 15 but you do not want to wait until
the service comes down naturally. To force TCS connections to be terminated, enter the following
command.
ServerIronADX(config)#server force-delete
Syntax: server force-delete
Passive FTP for TCS
Passive FTP (sometimes referred to as PASV FTP because it involves the FTP PASV command) is a
more secure form of data transfer in which the flow of data is set up and initiated by the File
Transfer Protocol (FTP) client rather than by the FTP server program. Most web browsers (which act
as FTP clients) use passive FTP by default because corporations prefer it as a safety measure. As a
general rule, any corporate firewall server that exists in order to protect an internal network from
the outside world recognizes input from the outside only in response to user requests that were
sent out requesting the input. The use of passive FTP ensures all data flow initiation comes from
inside the network rather than from the outside.
Traffic flow of passive FTP
Using normal or passive FTP, a client begins a session by sending a request to communicate
through TCP port 21, the port that is conventionally assigned for this use at the FTP server. This
communication is known as the Control Channel connection.