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BMD00220, October 2010 Chapter 14: FCoE and CEE . 201 BLADEOS 6.5.2 Application Guide PFC Configuration Example Note – DCBX may be configured to permit sharing or learning PFC configuration with or from external devices. This example assumes that PFC configuration is being performed manually. See “Data Center Bridging Capability Exchange” on page 211 for more information on DCBX. This example is consistent with the network shown in Figure 22 on page 189. In this example, the following topology is used. Table 18 Port-Based PFC Configuration Switch 802.1pPFC Usage Port Priority Setting 1 0-2 LAN Disabled 4 Business-critical LAN Enabled others (not used) Disabled 2 3 FCoE (to FCF bridge) Enabled others (not used) Disabled 3 3 FCoE Enabled others (not used) Disabled 4 0-2 LAN Disabled 4 Business-critical LAN Enabled others (not used) Disabled In this example, PFC is to facilitate lossless traffic handling for FCoE (priority value 3) and a business-critical LAN application (priority value 4). Assuming that CEE is off (the G8124 default), the example topology shown in Table 18 can be configured using the following commands: 1. Turn CEE on. RS G8124(config)# cee enable Note – Turning CEE on will automatically change some 802.1p QoS and 802.3x standard flow control settings and menus (see “Turning CEE On or Off” on page 192). 202 Chapter 14: FCoE and CEE BMD00220, October 2010 BLADEOS 6.5.2 Application Guide 2. Enable PFC for the FCoE traffic. Note – PFC is enabled on priority 3 by default. If using the defaults, the manual configuration commands shown in this step are not necessary. RS G8124(config)# cee global pfc priority 3 enable (Enable on FCoE priority) RS G8124(config)# cee global pfc priority 3 description "FCoE" (Optional description) 3. Enable PFC for the business-critical LAN application: RS G8124(config)# cee global pfc priority 4 enable (Enable on LAN priority) RS G8124(config)# cee global pfc priority 4 description "Critical LAN" (Optional description) 4. Save the configuration. BMD00220, October 2010 Chapter 14: FCoE and CEE . 203 BLADEOS 6.5.2 Application Guide Enhanced Transmission Selection Enhanced Transmission Selection (ETS) is defined in IEEE 802.1Qaz. ETS provides a method for allocating port bandwidth based on 802.1p priority values in the VLAN tag. Using ETS, different amounts of link bandwidth can specified for different traffic types (such as for LAN, SAN, and management). ETS is an essential component in a CEE environment that carries different types of traffic, each of which is sensitive to different handling criteria, such as Storage Area Networks (SANs) that are sensitive to packet loss, and LAN applications that may be latency-sensitive. In a single converged link, such as when implementing FCoE, ETS allows SAN and LAN traffic to coexist without imposing contrary handling requirements upon each other. The ETS feature requires CEE to be turned on (see “Turning CEE On or Off” on page 192). 802.1p Priority Values Under the 802.1p standard, there are eight available priority values, with values numbered 0 through 7, which can be placed in the priority field of the 802.1Q VLAN tag: 16 bits 3 bits 1 12 bits Tag Protocol ID (0x8100) Priority CFI VLAN ID 0 15 16 32 Servers and other network devices may be configured to assign different priority values to packets belonging to different traffic types (such as SAN and LAN). ETS uses the assigned 802.1p priority values to identify different traffic types. The various priority values are assigned to priority groups (PGID), and each priority group is assigned a portion of available link bandwidth. Priorities values within in any specific ETS priority group are expected to have similar traffic handling requirements with respect to latency and loss. 204 Chapter 14: FCoE and CEE BMD00220, October 2010 BLADEOS 6.5.2 Application Guide 802.1p priority values may be assigned by the administrator for a variety of purposes. However, when CEE is turned on, the G8124 sets the initial default values for ETS configuration as follows: Figure 23 Default ETS Priority Groups 802.1p Bandwidth Typical Traffic Type PGID Priority Allocation LAN 0 LAN 1 2 10% LAN 2 SAN 3 3 50% Latency-Sensitive LAN 4 Latency-Sensitive LAN 5 4 40% Latency-Sensitive LAN 6 Latency-Sensitive LAN 7 In the assignment model shown in Figure 23 on page 205, priorities values 0 through 2 are assigned for regular Ethernet traffic, which has “best effort” transport characteristics. Priority 3 is typically used to identify FCoE (SAN) traffic. Priorities 4-7 are typically used for latency sensitive traffic and other important business applications. For example, priority 4 and 5 are often used for video and voice applications such as IPTV, Video on Demand (VoD), and Voice over IP (VoIP). Priority 6 and 7 are often used for traffic characterized with a “must get there” requirement, with priority 7 used for network control which is requires guaranteed delivery to support configuration and maintenance...

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