Cisco 3945 User Manual

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Cisco 3900 Series, Cisco 2900 Series, and Cisco 1900 Series Integrated Services Routers Generation 2 Software Configuration Guide
Chapter Configuring Radio Settings
Disabling and Enabling Short Radio Preambles
Disabling and Enabling Short Radio Preambles
The radio preamble (sometimes called a header) is a section of data at the head of a packet that contains
information that the wireless device and client devices need when sending and receiving packets. You
can set the radio preamble to long or short:
• Short—A short preamble improves throughput performance.
• Long—A long preamble ensures compatibility between the wireless device and all early models of
Cisco Aironet Wireless LAN Adapters. If these client devices do not associate to the wireless
devices, you should use short preambles.
You cannot configure short or long radio preambles on the 5-GHz radio.
To disable short radio preambles, follow these steps, beginning in privileged EXEC mode:
SUMMARY STEPS
1. configure terminal
2. interface dot11radio {0| 1}
3. no preamble-short
4. end
5. copy running-config startup-config
DETAILED STEPS
Short preambles are enabled by default. Use the preamble-short command to enable short preambles if
they are disabled.
Command Purpose
Step 1
configure terminal Enters global configuration mode.
Step 2
interface dot11radio {0| 1} Enters interface configuration mode for the 2.4-GHz radio
interface.
Step 3
no preamble-short Disables short preambles and enable long preambles.
Step 4
end Returns to privileged EXEC mode.
Step 5
copy running-config startup-config (Optional) Saves your entries in the configuration file.

Cisco 3945 Specifications

General

Form Factor	Rack-mountable
Maximum Throughput	75 Mbps
Product Type	Router
Connectivity Technology	Wired
Data Link Protocol	Ethernet, Fast Ethernet, Gigabit Ethernet
Operating System	Cisco IOS
Flash Memory	256 MB
Network/Transport Protocol	IPSec
Remote Management Protocol	SNMP
Encryption Algorithm	DES, AES
Features	Firewall, VPN, Quality of Service (QoS), VLAN support
Interfaces	2 x USB
Security Features	Intrusion Prevention System (IPS)
Operating Temperature	32 °F to 104 °F (0 °C to 40 °C)
Storage Temperature	-4 °F to 149 °F (-20 °C to 65 °C)
Humidity	10 - 85% (non-condensing)
Memory	2 GB
Expansion Slots	4 (free) x EHWIC ¦ 2 x service module ¦ 1 x ISM ¦ 1 x CompactFlash Card