ZyXEL Communications VDSL SWITCH VES-1616F-3X - Manual (Page 75)

Chapter 6 Basic Setting
VES-1616F-3x Series User’s Guide
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6.8 VDSL Parameters
The following sections describe the VDSL parameters you configure in the following screens:
• VDSL Profile Setup (see Section 6.9 on page 77 ).
• VDSL Alarm Profile Setup (see Section 6.10 on page 80 ).
• VDSL PSD Profile Setup (see Section 6.11 on page 82 ).
6.8.1 Frequency Band Plan
Each VDSL mode operates in a different frequency band allocation, resulting in different
upstream and downstream speeds. Your VES switch automatically changes the band plan
based on the loop condition and loop length.
All of the band plans include an optional band. Use the optional band for upstream
transmission which is to be negotiated during line initiation.
6.8.2 Configured Versus Actual Rate
You configure the maximum rate of an individual VDSL port by modifying its profile (see the
VDSL Profile Setup screen) or assigning the port to a different profile (see the Port Setup
screen). However, the actual rate varies depending on factor such as transmission range and
interference.
Flow Control A concentration of traffic on a port decreases port bandwidth and overflows buffer
memory causing packet discards and frame losses. Flow Control is used to regulate
transmission of signals to match the bandwidth of the receiving port.
The switch uses IEEE802.3x flow control in full duplex mode and back pressure flow
control in half duplex mode.
IEEE802.3x flow control is used in full duplex mode to send a pause signal to the
sending port, causing it to temporarily stop sending signals when the receiving port
memory buffers fill.
Back Pressure flow control is typically used in half duplex mode to send a "collision"
signal to the sending port (mimicking a state of packet collision) causing the sending
port to temporarily stop sending signals and resend later. Select Flow Control to
enable it.
802.1P Priority This priority value is added to incoming frames without a (802.1p) priority queue tag.
See Priority Queue Assignment in Table 11 on page 68 for more information.
BPDU Control Configure the way to treat BPDUs received on this port. You must activate bridging
control protocol transparency in the Switch Setup screen first.
Select Peer to process any BPDU (Bridge Protocol Data Units) received on this port.
Select Tunnel to forward BPDUs received on this port.
Select Discard to drop any BPDU received on this port.
Select Network to process a BPDU with no VLAN tag and forward a tagged BPDU.
Apply Click Apply to save the settings.
Cancel Click Cancel to reset the fields to your previous configuration.
Table 13 Port Setup (continued)
LABEL DESCRIPTION