Nortel business policy switch 2000, Руководство пользователя

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Chapter 4 Policy-enabled networks 295
Using the Business Policy Switch 2000 Version 2.0
Refer to Table 57 and Table 58 for more information on layer 2 traffic, either IP or
non-IP, and trusted, untrusted, or unrestricted ports.
Ports
BPS 2000 ports are classified into three categories: trusted, untrusted, and
unrestricted ports. These three categories are also referred to as interface classes.
In your network, trusted ports are usually connected to the core of the DiffServ
network, and untrusted ports are typically access links that are connected to end
stations. Unrestricted ports can be either access links or connected to the core
network.
The classifications of trusted, untrusted, and unrestricted actually apply to groups
of ports (interface groups). Because a port can belong to only one interface group,
a port will be classified as trusted, untrusted, or unrestricted. These types are also
referred to as interface classes. So, you have three classes of interface groups:
Trusted, untrusted, and unrestricted. By default, all ports are untrusted.
Table 57 shows the configurations available to the user for each class of interface
for IP traffic (including layer 2 traffic matching IP) and layer 2, non-IP traffic.
Note:
Layer 2 filters should have the same evaluation order (or
precedence order) as shown in this example to ensure that IP traffic will
be treated properly.
Table 57 Possible user re-marking of QoS fields by class of interface
Type of filter Action Trusted Untrusted Unrestricted
IP filter or
Layer 2 filter
matching IP DSCP Cannot re-mark Must re-mark Re-mark or not
IEEE 802.1p Cannot re-mark Must re-mark Re-mark or not
Drop precedence Cannot re-mark Must re-mark Re-mark or not
Layer 2 filter
(non-IP) DSCP Cannot re-mark Cannot re-mark Cannot re-mark