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Example: Configuring Two or More Lossless FCoE Priorities on the Same FCoE Transit Switch Interface

The default system configuration supports FCoE traffic on priority 3 (IEEE 802.1p code point 011). If the FCoE traffic on your converged Ethernet network uses priority 3, the only user configuration required for lossless transport is to enable PFC on code point 011 on the FCoE ingress interfaces.

However, if your converged Ethernet network uses more than one priority for FCoE traffic, you need to configure lossless transport for each FCoE priority. This example shows you how to configure lossless FCoE transport on a converged Ethernet network that uses both priority 3 (IEEE 802.1p code point 011) and priority 5 (IEEE 802.1p code point 101) for FCoE traffic.

Requirements

This example uses the following hardware and software components:

  • One switch used as an FCoE transit switch

  • Junos OS Release 12.3 or later for the QFX Series

Overview

Some network topologies support FCoE traffic on more than one IEEE 802.1p priority. For example, a converged Ethernet network might include two separate FCoE networks that use different priorities to identify traffic. Interfaces that carry traffic for both FCoE networks need to support lossless FCoE transport on both priorities.

Supporting lossless behavior for two FCoE traffic classes requires configuring:

  • At least one lossless forwarding class for FCoE traffic (this example uses the default fcoe forwarding class as one of the lossless FCoE forwarding classes, so we need to explicitly configure only one FCoE forwarding class).

  • A behavior aggregate (BA) classifier to map the FCoE forwarding classes to the appropriate IEEE 802.1p code points (priorities).

  • A congestion notification profile (CNP) to enable PFC on the FCoE code points at the interface ingress and to configure PFC flow control on the interface egress so that the interface can respond to PFC messages received from the connected peer.

    Note:

    Configuring or changing PFC on an interface blocks the entire port until the PFC change is completed. After a PFC change is completed, the port is unblocked and traffic resumes. Blocking the port stops ingress and egress traffic, and causes packet loss on all queues on the port until the port is unblocked.

  • DCBX applications and an application map to support DCBX application TLV exchange for the lossless FCoE traffic on the configured FCoE priorities. By default, DCBX is enabled on all Ethernet interfaces, but only on priority 3 (IEEE 802.1p code point 011). To support DCBX application TLV exchange when you are not using the default configuration, you must configure all of the applications and map them to interfaces and priorities.

The priorities specified in the BA classifier, CNP, and DCBX application map must match, or the configuration does not work. You must specify the same lossless FCoE forwarding class in each configuration and use the same IEEE 802.1p code point (priority) so that the FCoE traffic is properly classified into flows and so that those flows receive lossless treatment.

Topology

This example shows how to configure two lossless FCoE traffic classes on an interface, map them to two different priorities, and configure flow control to ensure lossless behavior. This example uses two Ethernet interfaces, xe-0/0/20 and xe-0/0/21, that are connected to the converged Ethernet network. Both interfaces transport FCoE traffic on priorities 3 (011) and 5 (101), and must support lossless transport of that traffic.

Table 1 shows the configuration components for this example.

Table 1: Components of the Two Lossless FCoE Priorities on an Interface Configuration Topology

Component

Settings

Hardware

One switch

Forwarding classes

Name—fcoe1

Queue mapping—queue 5

Packet drop attribute—no-loss

Note:

A lossless forwarding class can be mapped to any output queue. However, because the fcoe1 forwarding class uses priority 5 in this example, matching that traffic to a forwarding class that uses queue 5 creates a configuration that is logical and easy to map because the priority and the queue are identified by the same number.

Name—fcoe

This is the default lossless FCoE forwarding class, so no configuration required. The fcoe forwarding class is mapped to priority 3 (IEEE 802.1p code point 011) and to output queue 3 with a packet drop attribute of no-loss.

BA classifier

Name—fcoe_classifier

FCoE priority mapping for forwarding class fcoe—mapped to code point 011 (IEEE 802.1p priority 3) and a packet loss priority of low.

FCoE priority mapping for forwarding class fcoe1—mapped to code point 101 (IEEE 802.1p priority 5) and a packet loss priority of low.

PFC configuration (CNP)

CNP name—fcoe_cnp

Input CNP code points—011 and 101

MRU—2240 bytes

Cable length—100 meters

Output CNP code points—011 and 101

Output CNP flow control queues—3 and 5

Note:

When you apply a CNP with an explicit output queue flow control configuration to an interface, the explicit CNP overwrites the default output CNP. The output queues that are enabled for PFC pause in the default configuration (queues 3 and 4) are not enabled for PFC pause unless they are included in the explicitly configured output CNP. In this example, because the explicit output CNP overwrites the default output CNP, we must explicitly configure flow control on queue 3.

DCBX application mapping

Application name—fcoe_app

Application EtherType—0x8906

Application map name—fcoe_app_map

Application map code points—011 and 101

Note:

LLDP and DCBX must be enabled on the interface. By default, LLDP and DCBX are enabled on all Ethernet interfaces.

Interfaces

Interfaces xe-0/0/20 and xe-0/0/21 use the same configuration:

  • Classifier—fcoe_classifier

  • CNP—fcoe_cnp

  • DCBX application map—fcoe_app_map

Note:

This example does not include scheduling (bandwidth allocation) configuration or the FIP snooping configuration. This examples focuses only on the lossless FCoE priority configuration.

QFX10000 switches do not support FIP snooping. For this reason, QFX10000 switches cannot be used as FCoE access transit switches. QFX10000 switches can be used as intermediate or aggregation transit switches in the FCoE path, between an FCoE access transit switch that performs FIP snooping and an FCF.

Configuration

CLI Quick Configuration

To quickly configure two lossless FCoE forwarding classes that use different priorities on an FCoE transit switch interface, copy the following commands, paste them in a text file, remove line breaks, change variables and details to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.

Procedure

Step-by-Step Procedure

To configure two lossless forwarding classes for FCoE traffic on the same interface, classify FCoE traffic into the forwarding classes, configure CNPs to enable PFC on the FCoE priorities and output queues, and configure DCBX application protocol TLV exchange for traffic on both FCoE priorities:

  1. Configure lossless forwarding class fcoe1 and map it to output queue 5 for FCoE traffic that uses IEEE 802.1p priority 5:

    Note:

    This examples uses the default fcoe forwarding class as the other lossless FCoE forwarding class.

  2. Configure the ingress classifier. The classifier maps the FCoE priorities (IEEE 802.1p code points 011 and 101) to lossless FCoE forwarding classes fcoe and fcoe1, respectively:

  3. Apply the classifier to the interfaces:

  4. Configure the CNP. The input stanza enables PFC on the FCoE priorities (IEEE 802.1p code points 011 and 101), sets the MRU value (2240 bytes), and sets the cable length value (100 meters). The output stanza configures flow control on output queues 3 and 5 on the FCoE priorities:

  5. Apply the CNP to the interfaces:

  6. Configure a DCBX application for FCoE to map to the Ethernet interfaces, so that DCBX can exchange application protocol TLVs on both of the IEEE 802.1p priorities used for FCoE transport:

  7. Configure a DCBX application map to map the FCoE application to the correct IEEE 802.1p FCoE priorities:

  8. Apply the application map to the interfaces so that DCBX exchanges FCoE application TLVs on the correct code points:

Verification

To verify the configuration and proper operation of the lossless forwarding classes and IEEE 802.1p priorities, perform these tasks:

Verifying the Forwarding Class Configuration

Purpose

Verify that the lossless forwarding class fcoe1 has been created.

Action

Show the forwarding class configuration by using the operational command show class-of-service forwarding class:

Meaning

The show class-of-service forwarding-class command shows all of the forwarding classes. The command output shows that the fcoe1 forwarding class is configured on output queue 5 with the no-loss packet drop attribute enabled.

Because we did not explicitly configure the default forwarding classes, they remain in their default state, including the lossless configuration of the fcoe and no-loss default forwarding classes.

Verifying the Behavior Aggregate Classifier Configuration

Purpose

Verify that the three classifiers map the forwarding classes to the correct IEEE 802.1p code points (priorities) and packet loss priorities.

Action

List the classifiers using the operational mode command show class-of-service classifier:

Meaning

The show class-of-service classifier command shows the IEEE 802.1p code points and the loss priorities that are mapped to the forwarding classes in each classifier.

Classifier fcoe_classifier maps code point 011 to default lossless forwarding class fcoe and a packet loss priority of low, and maps code point 101 to explicitly configured lossless forwarding class fcoe1 and a packet loss priority of low.

Verifying the PFC Flow Control Configuration (CNP)

Purpose

Verify that PFC is enabled on the correct input priorities and that flow control is configured on the correct output queues and priorities.

Action

List the CNPs using the operational mode command show class-of-service congestion-notification:

Meaning

The show class-of-service congestion-notification command shows the input and output stanzas of the CNP.

The CNP fcoe_cnp input stanza shows that PFC is enabled on code points 011 and 101, the MRU is 2240 bytes on both priorities, and the interface cable length is 100 meters. The CNP output stanza shows that output flow control is configured on queues 3 and 5 for code points 011 and 101, respectively.

Verifying the Interface Configuration

Purpose

Verify that the classifier and congestion notification profile are configured on the interfaces. Both interfaces should show the same configuration.

Action

List the ingress interfaces using the operational mode commands show configuration class-of-service interfaces xe-0/0/20 and show configuration class-of-service interfaces xe-0/0/21:

Meaning

The show configuration class-of-service interfaces xe-0/0/20 command shows that the congestion notification profile fcoe_cnp is configured on the interface, and that the IEEE 802.1p classifier associated with the interface is fcoe_classifier.

The show configuration class-of-service interfaces xe-0/0/21 command shows that the congestion notification profile fcoe_cnp is configured on the interface, and that the IEEE 802.1p classifier associated with the interface is fcoe_classifier.

Verifying the DCBX Application Configuration

Purpose

Verify that the DCBX application for FCoE is configured.

Action

List the DCBX applications by using the configuration mode command show applications:

Meaning

The show applications configuration mode command shows all of the configured applications. The output shows that the application fcoe_app is configured with an EtherType of 0x8906.

Verifying the DCBX Application Map Configuration

Purpose

Verify that the application map is configured.

Action

List the application maps by using the configuration mode command show policy-options application-maps:

Meaning

The show policy-options application-maps configuration mode command lists all of the configured application maps and the applications that belong to each application map. The output shows that application map fcoe_app_map consists of the application named fcoe_app, which is mapped to IEEE 802.1p code points 011 and 101 (priorities 3 and 5, respectively).

Verifying the DCBX Application Protocol Exchange Interface Configuration

Purpose

Verify that the application map is applied to the interfaces.

Action

List the application maps on each interface using the configuration mode command show protocols dcbx:

Meaning

The show protocols dcbx configuration mode command lists the application map association with interfaces. The output shows that interfaces xe-0/0/20.0 and xe-0/0/21.0 use application map fcoe_app_map.