Header Compression Configuration Options - Avaya G450 Manual

Configuring VoIP QoS
The G450 offers both RTP header compression, for reducing the amount of bandwidth needed
for voice traffic, and TCP and UDP header compression, for reducing the amount of bandwidth
needed for non-voice traffic.
For header compression purposes, any UDP packet with an even destination port within a
user-configurable range of ports, is considered an RTP packet.
The G450 enables decompression whenever compression is enabled. However, when enabling
header compression on a Frame Relay interface, you must first verify that the remote host is
also employing header compression. Header compression on a Frame Relay interface does not
check what the remote host is employing. Thus, it may compress headers even when the
remote host is not configured to decompress headers.
You can configure how often a full header is transmitted, either as a function of time or of
transmitted compressed packets.

Header compression configuration options

The G450 offers two options for configuring header compression:
IP Header compression (IPHC) method, as defined by RFC 2507. IPHC-type compression
●
applies to RTP, TCP, and UDP headers.
Van Jacobson (VJ) method, as defined in RFC 1144. VJ compression applies to TCP
●
headers only.
Note:
VJ compression and IPHC cannot co-exist on an interface, and IPHC always
Note:
overrides VJ compression. Thus, if you define both VJ compression and IPHC,
only IPHC is enabled on the interface regardless of the order of definition.
Table 61: Header compression support by interface
Interface type
Serial
PPP
Sub-Frame-Relay with IETF
encapsulation
Sub-Frame-Relay with non-IETF
encapsulation
Dialer
226 Administration for the Avaya G450 Media Gateway
Supported compression methods
IPHC and VJ
IPHC only
RTP header compression using the IPHC
method, and TCP header compression using
the VJ method
IPHC and VJ