Ethernet Interface Configurations - Sagem -LINK F Installation And Operation Manual

SAGEM-LINK F
Installation and Operation Manual
transmit outgoing frames, only MACs/VLANs that continually communicate with the Service Network
are assigned queues.
The Public Queue is used to store frames from Source Address/VLAN IDs that have not been
assigned a Private Queue. The Subscriber Queue is used to store frames traversing from the Service
Network to the Subscriber Network. Since there is typically no bottleneck in this direction, one queue
is sufficient.
6.3.2.3 - Aging and Queue Recovery
Aging and queue recovery mechanisms enable the SAGEM LINK F to react dynamically to changes in
traffic patterns. Queues assigned to Source Addresses/VLAN IDs that become inactive are soon
released and made available to other Source Addresses /VLAN IDs. In this way, only network
devices/VLANs that communicate with the Service Network get Private Queues and their fair share of
the bandwidth.
The aging mechanism identifies network devices/VLANs on the Subscriber Network that have
stopped communicating with the Service Network (regardless of whether or not they communicate
locally). Such network devices/VLANs do not need to be allocated any Service Network bandwidth.
A time-stamp field in each BA Table entry makes aging possible. Expanding on the learning process
described above:
1. If a Private Queue has already been assigned to the SA/VLAN ID then its time-stamp is updated
2. If a Private Queue has not yet been assigned to the SA/VLAN ID, but one is available, then a
Private Queue is designated for that SA/VLAN ID and its time-stamp is recorded.
The time-stamp of each Private Queue is pre-loaded to age within 6 seconds the first time a frame
enters the queue. If no Service Network traffic follows within that period, the Private Queue is aged
and recovered. This enables the system to react quickly upon start-up. All frames that follow are time-
stamped for 300 second aging.
The Queue Recovery mechanism works as follows:
1. When a Private Queue is available the SAGEM LINK F polls the MAC Table every 6 seconds
to find the device or VLAN with the most Service Network traffic that does not have a Queue
assigned to it.
2. It assigns a Private Queue to that Source Address/VLAN ID and updates that entry in the BA
Table. After a Private Queue is released, the queue remains available until a device (that has
not yet been assigned a Private Queue) starts communicating across the Service Network.
6.3.2.4 - Scheduling
The Bandwidth Allocator schedules transmission out of the queues and to the Service Interface. It
applies a Deficit Round Robin algorithm in which each active queue is weighted equally. This ensures
that all active queues get an equal portion of the available bandwidth. Inactive queues are ignored by
the scheduler and receive no bandwidth.
6.3.3 – Ethernet Interface Configurations
The Ethernet Interface of the SAGEM LINK F radios can be connected to any Ethernet device
compliant with IEEE 802.3 standard.
The configurable features of Ethernet Interface are :
• 10 baseT (10 Mbit/s) or 100 baseT (100 Mbit/s)
•
Half Duplex (transmit and receive frames processed separately) or Full Duplex (transmit and
receive frames processed simultaneously)
•
Autonegotiation protocol for 10 baseT/100 baseT and Half Duplex/Full Duplex selections
•
Flow Control
Reproduction and communication prohibited without the written permission of Sagem Communication
288055571-04
Page 121/142
Issue 04 : July 2005