Cisco ME 3400 User Manual

33-6
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-07
Chapter 33 Configuring QoS
Understanding QoS
• Layer 3 IP packets can carry either an IP precedence value or a DSCP value. QoS supports the use
of either value because DSCP values are backward-compatible with IP precedence values.
IP precedence values range from 0 to 7. DSCP values range from 0 to 63.
• Output remarking is based on the Layer 2 or Layer 3 marking type, marking value and packet type.
Figure 33-3 QoS Classification Layers in Frames and Packets
These sections contain additional information about classification:
• “Class Maps” section on page 33-7
• “The match Command” section on page 33-7
• “Classification Based on Layer 2 CoS” section on page 33-8
• “Classification Based on IP Precedence” section on page 33-8
• “Classification Based on IP DSCP” section on page 33-8
• “Classification Comparisons” section on page 33-9
• “Classification Based on QoS ACLs” section on page 33-10
• “Classification Based on QoS Groups” section on page 33-10
• “Classification Based on VLAN IDs” section on page 33-12
141151
Layer 2 IEEE 802.1Q and IEEE 802.1p Frame
Preamble
Start frame
delimiter
DA
Len
SA Type
TAG
2 Bytes
PT Data FCS
Layer 3 IPv4 Packet
Version
length
To S
1 Byte
ID Offset TTL Proto FCS IP-SA IP-DA
PRI
7
6 5 4 3 2 1 0
CFI VLAN ID
Data
3 bits used for CoS
(IEEE 802.1p user priority)
IP precedence
DSCP
Standard IPv4:
MSBs called IP precedence
Flow control
for DSCP

Cisco ME 3400 Specifications

General

Category	Switch
Rack Mountable	Yes
Jumbo Frame Support	Yes
Authentication Method	RADIUS, TACACS+
RAM	128 MB
Flash Memory	32 MB
Power Device	Internal power supply
Model	ME 3400
Layer	Layer 2
MAC Address Table Size	8000 entries
Remote Management Protocol	SNMP, Telnet, SSH, HTTP, HTTPS
Features	VLAN support, IGMP snooping, Quality of Service (QoS)
Compliant Standards	IEEE 802.3, IEEE 802.3u, IEEE 802.1D, IEEE 802.1Q, IEEE 802.3ab, IEEE 802.3x
Memory	128 MB
Power Supply	AC 120/230 V (50/60 Hz)
Dimensions (H x W x D)	4.4 cm x 44.5 cm x 24.2 cm
Routing Protocol	Static routing