Reference Guide

Service Provider Bridging | 833
To map C-Tag dot1p values to S-Tag dot1p values and mark the frames accordingly:
Layer 2 Protocol Tunneling
Layer 2 Protocol Tunneling (L2PT) is supported on platforms: c e s z
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 VLAN stacking is used to connect physically separate regions of a network, BPDUs attempting to
traverse the intermediate network might be consumed and subsequently dropped because the intermediate
network itself might be using Spanning Tree (Figure 41-13).
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
Default: 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. C-Tag values may be separated by
commas, and 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: Since dot1p-mapping marks and queues packets, the only remaining applicable QoS configuration
is rate metering. You may use Rate Shaping or Rate Policing.