User Manual

Additional Remote Networking Bandwidth On Demand
5-6
The SCS will always use at least one port for a connection, even if the traffic is below the “remove
bandwidth” threshold. If this is not desired behavior, the last connection can be controlled by the idle timer.
Note: To configure the idle timer, see Set/Define Server Inactivity on page 12-120.
5.3.2 Disadvantages of Additional Bandwidth
Increasing bandwidth by bringing up additional links has two disadvantages: increased cost and reduced
resources. Phone rates will go up as more phone lines are used, and fewer ports will be available for other
purposes. Assess your needs carefully before increasing bandwidth.
5.3.3 Configuring Bandwidth Allocated to Sites
To configure bandwidth, follow the instructions in the following sections.
5.3.3.1 Estimate Each Port’s Bandwidth
Before sites can be configured to use particular bandwidths, the bandwidth of each SCS port must be
estimated in bytes per second. This estimate should be made based upon two factors: the amount of
compression expected for typical data on this site, and the fastest data transfer rate that the local and remote
modems can support.
The SCS will truncate the bandwidth setting to the nearest 100 bytes per second. For example, a setting of
5790 will be truncated to 5700.
Consider the following example. Site irvine may use SCS port 2 and port 3 (if needed) for connections. A
V.34 modem with a baud rate of 28800 bits per second is attached to each port. The remote modems are
also V.34 modems with the same baud rate. Compression is enabled and a 2:1 compression rate is expected,
which will increase the data transfer between the modems to 57600 bits per second.
The bandwidth for ports 2 and 3 should be estimated as follows:
Figure 5-8: Estimating a Port’s Bandwidth
Note: If you are using 8 bits, no parity, and 1 stop bit, the modem will actually transmit
ten bits for each byte.
If the modems attached to a series of SCS ports are going to be calling similar remote modems, these ports
should be set to the same bandwidth estimates. In addition, if several ports have compression enabled, you
should assume that the compression rate on each port will be the same (for example, a 2:1 compression rate).
Avoid using small variations in bandwidth estimates.
It is important to correctly estimate bandwidth. The SCS will attempt to reduce the total number of ports in
use by using higher bandwidth ports (of the same priority) first until the bandwidth goal is met.
Local>> DEFINE SITE irvine PORT 2 BANDWIDTH 5800
Local>> DEFINE SITE irvine PORT 3 BANDWIDTH 5800