User guide

i-3
iMG/RG Software Reference Manual (Preface)
IV Allied Telesis Gateway Family Feature Summary
IV.I VLAN OPERATION
This family of devices supports IEEE 802.1Q tagged VLAN operation across its all switch ports. It therefore
offers a powerful combination of wirespeed Layer 2 switching between VLANs as well as high performance
Layer 3 routing between VLANs in one highly cost effective unit.
IV.II FIREWALL
This family of devices integrates a Stateful Inspection Firewall with Network Address Translation (NAT) and
Denial of Service intrusion detection and blocking for protecting customer networks. Each VLAN can be
configured to be external, internal, or DMZ. With the Virtual Server features, a web or e-mail server can sit
beyond the NAT and appear like being on the public interface. The NAT implementation supports the most
popular protocols and applications including NetMeeting (H.323 and SIP), IPSec and PPPtp.
IV.III PORT RATE LIMITING
This family of devices offers the possibility to limit the egress and ingress bandwidth on each port. This feature
allows the Service Operator to offer differentiated services to each customer and protect its network from
malicious packet flooding.
IV.IV VOICE OVER IP (VOIP)
This family of devices offer a choice of Voice over IP signaling methods, namely SIP and MGCP including NCS
1.0 profile. SIP and MGCP are optimized for operation over IP networks. This multiple protocol support
provides maximum flexibility for service providers, allowing them to provide an IP telephony service based on
cost and feature set, rather than being limited by the protocol used.
Similarly, a choice of different voice and data encoding algorithms is also available comprising G.711 A-law, μ-law (64kbps),
G.729 (8kbps,) and T.38, so that maximum VoIP interworking is assured with carrier class IP Gateways and network
switches. Quality of Service is provided through mechanisms such as the Type of Service (ToS) field in the IP packet, priority
tagging of voice traffic using IEEE 802.1p, as well as silence suppression and local generation of comfort noise – the result is
excellent voice quality.
Class 5 services are supported and the VoIP inter-operability has been certified versus major soft-switch
vendors.
IV.V VIDEO STREAMING
Video Streaming offers unique features to optimize the delivery of Video contents to customers, namely VLAN,
IGMP snooping, and proxying. This family of devices supports full IGMP snooping capability (v1/v2), and
individual LAN ports can receive different multicast transmissions e.g. different movies or TV channels. The
gateway ‘snoops’ IGMP packets in-transit, so it knows which port to forward the particular multicast data to.