Product manual

Product Manual - DM991 Series V Family - 204.4092.08 27
6. ETHERNET INTERFACE
The DM991SE and DM991CE Ethernet interfaces allow interconnecting two LANs thru G.shdsl
aggregated. It can be configured to Nx64kbit/s speed, to the aggregate configured limit. This tributary can
be used joined with other modem tributaries.
Accepts packets of up to 1552 bytes, supporting VLAN.
6.1. Ethernet physical level
The DM991CE and DM991SE converters Ethernet interface is 10/100BaseT, according to the IEEE 802.3
specification.
The connection to the Ethernet interface is done through an RJ45 connector, seen in the front panel. The
connector pinout is such that allows the use of straight cables to connect the equipment to Ethernet hubs.
6.2. Remote Bridge
The bridge’s basic function is to segment a local network, avoiding all the Ethernet traffic to be transmitted
by the local equipment to the remote equipment, wasting band.
To do so, the bridge can automatically learn the MAC addresses of the stations connected to the local
network. In that way, it can filter the network traffic and transmit to the WAN side only the packets
corresponding to the MAC addresses that do not pertain to the local network, besides broadcast and
multicast packets.
The bridge operates on the MAC level of the Ethernet interface. In this way the tributary is completely
transparent for upper layers protocols, such as TCP/IP, UDP, etc.
The bridge local address table can store up to 1.000 MAC addresses. If a station remains inactive for
more than five minutes, its address will be removed from the table.
The process of filtering the packets to be transmitted imposes no limitation to the data flow. The delay
introduced by the Bridge processing is of only 1 Ethernet frame.
The bridge has a buffer to Ethernet -> G.shdsl that may store up 322 packages Ethernet with 1552 bytes,
but smaller packages may be stored in greater quantity.
In order G.shdsl -> Ethernet has a buffer of 64 packets of 1552 bytes Ethernet. Similarly, using smaller
packages permites store more ones. Using this direction there is no filtering, because it has already been
done by the bridge from remote equipment.
6.3. Ethernet Interface Configurations
The following interface configurations are possible:
• WAN Speed - It allows for the selection from 1 to 36 64-kbit/s time slots on 2-wire
modems (2W), and from 1 to 72 time slots on 4-wire modems (4W);
• Self-negotiation - allows negotiation with the equipment connected by the Ethernet
interface on the operating mode, interface velocity, and flow control use;
• Duplex - it is possible to choose between the Full-Duplex (both sides transmit
simultaneously) and Half-Duplex modes (one side transmits at a time);