Comtech EF Data CDD-562L - Manual (Page 60)

CDD-562L/564 Demodulator with IP Module Revision 2
IP Module Ethernet Interface MN/CDD564L.IOM
4–4
4.2.1 3xDES Encryption with Ability to Change Keys
The demodulator optionally supports 3xDES-128 (using NIST certified 3x core) decryption for
the highest-level security. For link encryption, each unit supports eight decryption keys.
4.2.2 IP Header Compression
Header Compression also is an optional feature of the demodulator. The demodulator supports
Header Compression for the following Ethernet and Layer 3 & 4 Headers:
Supported Ethernet Headers
Ethernet 2.0
Ethernet 2.0 + VLAN-tag
Ethernet 2.0 + MPLS
802.3-raw
802.3-raw + VLAN-tag
802.3 + 802.2
802.3 + 802.2 + VLAN-tag
802.3 + 802.2 + SNAP
802.3 + 802.2 + SNAP + VLAN-tag
802.3 + 802.2 + SNAP + MPLS
Supported Layer 3&4 Headers
IP
TCP
UDP
RTP (Codec Independent)
Header Compression reduces the required VoIP bandwidth by 60 percent. Example: A G.729a
voice codec, operating at 8 kbps, will occupy 32 kbps once encapsulated into IP framing on a
LAN. Using IP/UDP/RTP Header Compression, the same traffic only needs 10.8 kbps total WAN
satellite bandwidth to cross the link. A total maximum of 64 simultaneous VoIP calls can be
compressed. Normal Web/HTTP traffic can be reduced an additional 10% via IP/TCP header
compression.
Header Compression Configuration – Header Compression is completely independent from
QoS, and there is no configuration required except enabling the Header Compression feature on
both the sending and receiving Comtech EF Data IP modem/demod. Packets with a Header
Compression supported header will automatically be identified for compression. The only
configuration consideration is the Header Compression Refresh Rate. This is how many
compressed header packets will be sent before a single full header packet is sent. Sometimes
compressed header traffic could be lost during deteriorated satellite link conditions. Sending a full
header packet will allow the return of the traffic stream. The Refresh Rate can be increased for
poor satellite link conditions or decreased to further reduce overhead.