Reference Guide

830 | Service Provider Bridging
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Mapping C-Tag to S-Tag dot1p Values
To map C-Tag dot1p values to S-Tag dot1p values and mark the frames accordingly, use the following
commands:
Layer 2 Protocol Tunneling
Spanning Tree BPDUs use a reserved destination MAC address called the Bridge Group Address, which is
01-80-C2-00-00-00.
Only spanning-tree bridges on the LAN recognize this address and process the BPDU. When you use
VLAN stacking to connect physically separate regions of a network, BPDUs attempting to traverse the
intermediate network might be consumed and later dropped because the intermediate network itself might
be using spanning tree (Figure 45-10).
Step Task Command Syntax Command Mode
1 Allocate CAM space to enable queuing
frames according to the C-Tag or the
S-Tag.
vman-qos: mark the S-Tag dot1p and
queue the frame according to the original
C-Tag dot1p. This method requires half as
many CAM entries as
vman-qos-dual-fp.
vman-qos-dual-fp: mark the S-Tag dot1p
and queue the frame according to the
S-Tag dot1p. This method requires twice
as many CAM entries as
vman-qos and FP
blocks in multiples of 2.
cam-acl l2acl number ipv4acl number
ipv6acl number ipv4qos number l2qos
number l2pt number ipmacacl number
ecfmacl number {vman-qos |
vman-qos-dual-fp} number
The default is: 0 FP blocks for vman-qos
and
vman-qos-dual-fp.
CONFIGURATION
2 The new CAM configuration is stored in
NVRAM and takes effect only after a save
and reload.
copy running-config startup-config
reload
EXEC Privilege
3 Map C-Tag dot1p values to a S-Tag dot1p
value.
Separate C-Tag values by commas. Dashed
ranges are permitted.
Dynamic Mode CoS overrides any Layer 2
QoS configuration in case of conflicts.
vlan-stack dot1p-mapping c-tag-dot1p
values sp-tag-dot1p value
INTERFACE
Note: Because dot1p-mapping marks and queues packets, the only remaining applicable QoS
configuration is rate metering. You may use Rate Shaping or Rate Policing.