Header Compression Configuration Options - Avaya G250 Administration

Configuring VoIP QoS
The G250/G350 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 G250/G350 enables decompression whenever compression is enabled. However, when
enabling header compression on a Frame Relay interface, you must first make sure 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 G250/G350 offers two options for configuring header compression:
IPHC (IP Header compression) method, as defined by RFC 2507. IPHC-type compression
●
applies to RTP, TCP and UDP headers.
VJ (Van Jacobson) method, as defined in RFC 1144. VJ-type compression applies to TCP
●
headers only.
Note:
VJ compression and IPHC compression cannot co-exist on an interface, and
Note:
IPHC compression always overrides VJ compression. Thus, if you define both VJ
compression and IPHC compression, only IPHC compression is enabled on the
interface regardless of the order of definition.
Table 38: Header compression support by interface
Interface type
Serial
PPP
Sub-Frame-Relay with IETF
encapsulation
Sub-Frame-Relay with non-IETF
encapsulation
Dialer
202 Administration for the Avaya G250 and Avaya G350 Media Gateways
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