Hol Blocking Prevention - D-Link xStack DGS-3420 Series Reference Manual

xStack® DGS-3420 Series Layer 2 Managed Stackable Gigabit Switch Web UI Reference Guide
The fields that can be configured are described below:
Parameter
Unit
From Port / To Port
DSCP Map
DSCP List (0-63)
Priority
DSCP (0-63)
Port
Click the Apply button to accept the changes made.
Click the Find button to locate a specific entry based on the information entered.

HOL Blocking Prevention

HOL (Head of Line) Blocking happens when one of the destination ports of a broadcast or multicast packet are busy.
The switch will hold this packet in the buffer while the other destination port will not transmit the packet even they are
not busy.
The HOL Blocking Prevention will ignore the busy port and forward the packet directly to have lower latency and better
performance.
On this page the user can enable or disable HOL Blocking Prevention.
To view the following window, click QoS > HOL Blocking Prevention, as show below:
Figure 6-9 DSCP Map Settings - DSCP DSCP window
Description
Select the unit you want to configure.
Use the drop-down menu to select a range of port to configure.
Use the drop-down menu to select one of two options:
DSCP Priority – Specify a list of DSCP values to be mapped to a specific priority.
DSCP DSCP – Specify a list of DSCP value to be mapped to a specific DSCP.
Enter a DSCP List value.
Use the drop-down menu to select a Priority value. This appears when selecting DSCP
Priority in the DSCP Map drop-down menu.
Enter a DSCP value. This appears when selecting DSCP DSCP in the DSCP Map
drop-down menu.
Use the drop-down menu to select a port.
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