Brocade Fabric OS FCIP Administrator's Guide v7.1.0 (53-1002748-01, March 2013)

Fabric OS FCIP Administrator’s Guide 25

53-1002748-01

QoS, DSCP, and VLANs

• QoS priority settings must be the same on each end of the tunnel.

NOTE

Priorities are enforced only when there is congestion on the network. If there is no congestion, all

traffic is handled at the same priority.

Following are some examples of setting QoS priority levels on VE_Port 12:

• The following command sets the QoS high priority to 60 percent.

portcfg fciptunnel 1/12 create --qos-high 60

• The following command sets the QoS medium priority to 30 percent.

portcfg fciptunnel 1/12 create --qos-medium 30

• The following command sets the QoS low priority to 10 percent.

portcfg fciptunnel 1/12 create --qos-low 10

• The following command displays details of the FCIP tunnel configuration, including set QoS

percentages.

portshow fciptunnel 1/12

For more information on using Fabric OS commands, optional arguments, and command output

refer to the Fabric OS Command Reference Manual.

QoS, DSCP, and VLANs

Quality of Service (QoS) refers to policies for handling differences in data traffic. These policies are

based on data characteristics and delivery requirements. For example, ordinary data traffic is

tolerant of delays and dropped packets, but real-time voice and video data are not. QoS policies

provide a framework for accommodating these differences in data as it passes through a network.

QoS for Fibre Channel traffic is provided through internal QoS priorities. Those priorities can be

mapped to TCP/IP network priorities using zone name prefixes and VCs. The different priority TCP

sessions can be marked upon egress. The TCP marking is done at the IP layer using Layer 3

Differentiated Services Code Point (DSCP) or at the Ethernet layer within the 802.1Q tag header

using 802.1P. There are two options for TCP/IP network-based QoS:

• DSCP

• VLAN tagging and Layer 2 Class of Service (L2CoS)

QoS, DSCP & VLANs are configured at the FCIP circuit level and not at the tunnel level

DSCP Quality of Service

Layer 3 Class of Service Differentiated Services Code Point (DSCP) refers to a specific

implementation for establishing QoS policies as defined by RFC 2475. DSCP uses six bits of the

Type of Service (TOS) field in the IP header to establish up to 64 different values to associate with

data traffic priority.