METRObility Optical Systems R821-1S, Инструкция по установке и эксплуатации

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Management
to the queue that was used to store the frame. This is illustrated in the
following example in which the PVID is set to 2 and the tagged frame
has a VLAN ID of 25.
•
If a received frame contains DSCP and/or p-bit elements, and the
respective classification mode(s) is/are enabled, then that information
will be used to perform internal queuing, otherwise the access port’s
default port priority will be used for queuing.
Traffic Filtering and Forwarding Over the Access Port
•
Priority-tagged frames (i.e., frames with a VLAN ID of 0) arriving at
the trunk port are discarded.
•
Untagged frames, including untagged Layer 2 control protocols,
arriving at the trunk port are discarded.
•
User frames that are single-tagged with the PVID are forwarded, but
with the tag removed.
•
User frames that are double-tagged with the PVID are forwarded as
a single-tagged frame. The outer tag, which contains the PVID, is
deleted. The p-bits in the forwarded frames are derived from the p-
bits assigned to the queue that was used to store the frame.
•
User frames which do not include the PVID are dropped.
•
If the received frame contains DSCP and/or p-bit elements, that
information will be used to perform internal queuing, otherwise the
access port’s default port priority will be used for queuing.
The following example illustrates how different types of frames are
processed when they arrive at the trunk port in Q-in-Q mode.
R821
Access
Port
Trunk
Port
Q-in-Q Mode
PVID = 2
(p-bits = assigned queue)
untagged
tagged
tagged
double-tagged
25
25
2
2