Cisco Catalyst 3550 Series User Manual

29-6
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-09
Chapter 29 Configuring QoS
Understanding QoS
Figure 29-3 Classification Flowchart
46976
Generate the DSCP
based on IP precedence
in packet. Use the
IP-precedence-to-DSCP map.
Assign default
port CoS.
Ye s
Ye s
No
No
No
Ye s N o
(Optional) Modify the
DSCP by using the
DSCP-to-DSCP-mutation
map.
Read ingress interface
configuration for classification.
Assign DSCP identical
to DSCP in packet.
Check if packet came
with CoS label (tag).
Generate DSCP from
CoS-to-DSCP map.
Ye s
Read next ACL. Is there
a match with a "permit" action?
Assign the DSCP as
specified by ACL action.
Assign the default
DSCP (0).
Are there any (more) QoS ACLs
configured for this interface?
Check if packet came
with CoS label (tag).
Use Cos
from frame.
Start
Trust CoS (IP and non-IP traffic).
IP and
non-IP
traffic
Use port
default
(non-IP traffic).
Trust IP
precedence
(IP traffic).
Trust DSCP (IP traffic).
DoneDone
Done
Done
Assign the default port
CoS and generate a
DSCP from the
CoS-to-DSCP map.
Generate the DSCP by using
the CoS-to-DSCP map.

Cisco Catalyst 3550 Series Specifications

General

Form Factor	Rack-mountable
Manageable	Yes
RAM	64 MB
Device Type	Switch
MAC Address Table Size	12000 entries
Routing Protocol	RIP
Features	VLAN support
Power Supply	AC 120/230 V (50/60 Hz)
Ports	24 or 48 x 10/100Base-TX, 1 x GBIC, 2 x 10/100/1000Base-T
Operating Temperature	32 to 113°F (0 to 45°C)