Alcatel-Lucent 9500 MXC, Руководство пользователя

Страница: 457 / 916

9500 MXC User Manual
3DB 23063 ADAA - Rev 004 July 2007 Vol. IV-7-67
being broken down into smaller units (fragmented). The MTU should be
larger than the largest datagram you wish to transmit unfragmented
5
.
• The setable frame-size range is 64 to 9600 bytes, however it should not be
set above 7500 bytes for bi-directional traffic. 9600 can be used for
uni-directional requirements; frame sizes to 9600 bytes in one direction, and
normal frame sizes in the other direction. In practice frame sizes above 4000
bytes are seldom used.
• When operating with a DAC ES / IDU ES at the far end bear in mind that
their maximum frame size setting is 1536 bytes.
8.
Enable Flow Control
: Flow control is an option for full-duplex links only. It
is implemented by the of IEEE 802.3x pause frame mechanism, which tells
the remote node to stop or restart transmission to ensure that the amount of
data in the ingress queue does not exceed a ‘high water mark’.
• The receiver will signal to the transmitter to stop transmitting until sufficient
data has been read from the queue, triggered by a ‘low water mark’, at which
point the receiver signals to the transmitter to resume transmission.
• To be effective, flow control must be established from the originating source
through to the end point, and vice versa, which means the equipment
connected to DAC GE ports and beyond must also be enabled for flow
control.
9.
Disable Address Learning
: Address Learning is default implemented to
support efficient management of Ethernet traffic in multi-host situations. The
option to disable Address Learning is for use in a ring/mesh network where
protection is provided by an
external RSTP switch. To avoid conflict between
the self-learning function within DAC GE and the external RSTP switch
during path failure situations, the DAC GE capability must be disabled.
Failure to do so means that in the event of a path failure, and subsequent
re-direction of Ethernet traffic by the external switch to the alternate path, the
DAC GE will inhibit re-direction of current/recent traffic until its address
register matures and deletes unused/un-responsive destination addresses,
which may take up to 5 minutes.
10.
Enable Link Status Propagation
: Link Status Propagation is used to enhance
rapid detection by externally-connected equipment of the status of a DAC GE
channel. It does so by capturing the channel status (up/down) on the DAC GE
ports to force a port shutdown in the event of a channel failure. A port
shutdown is immediately detected by the connected equipment so that it can
act on applicable RSTP or link aggregation switching options. Specifically, it
supports:
5
The setting only supports this interface. Some other link/interface in the path may have a smaller MTU,
at which point the datagram will be fragmented if its size is greater.