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Example: Configuring Lossless FCoE Traffic When the Converged Ethernet Network Does Not Use IEEE 802.1p Priority 3 for FCoE Traffic (FCoE Transit Switch)

Requirements

• One Juniper Networks QFX3500 Switch in transit switch (FIP snooping) mode
• Junos OS Release 12.3 or later for the QFX Series

Overview

Although FCoE traffic typically uses IEEE 802.1p priority 3 on converged Ethernet networks, some networks use a different priority for FCoE traffic. Regardless of the priority used, FCoE traffic must receive lossless treatment. Supporting lossless behavior for FCoE traffic when your network does not use priority 3 requires configuring:

• A lossless forwarding class for FCoE traffic.
• A behavior aggregate (BA) classifier to map the FCoE forwarding class to the appropriate IEEE 802.1p priority.
• A congestion notification profile (CNP) to enable PFC on the FCoE code point at the interface ingress and to configure flow control on the interface egress. Flow control on the interface egress enables the interface to respond to PFC messages received from the connected peer and pause the correct IEEE 802.1p priority on the correct output queue.

  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.

• A DCBX application and an application map to support DCBX application TLV exchange for the lossless FCoE traffic on the configured FCoE priority. 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 classifiers, 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 one lossless FCoE traffic class, map it to a priority other than priority 3, and configure flow control to ensure lossless behavior on the interfaces. This example uses two Ethernet interfaces, xe-0/0/25 and xe-0/0/26. The interfaces connect to a converged Ethernet network that uses IEEE 802.1p priority 5 (code point 101) for FCoE traffic.

The configuration on the two interfaces is the same. Both interfaces use the same explicitly configured lossless FCoE forwarding class and the same ingress classifier. Both interfaces enable PFC on priority 5 and enable flow control on the same output queue (which is mapped to the lossless FCoE forwarding class).

Table 1 shows the configuration components for this example.

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.

Configuration

CLI Quick Configuration

To quickly configure a lossless FCoE forwarding class that uses a different priority than IEEE 802.1p priority 3 for FCoE traffic on an FCoE transit switch, 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.

Configuring A Lossless FCoE Forwarding Class On IEEE 802.1p Priority 5

Step-by-Step Procedure

1. Configure the lossless forwarding class (named fcoe1 and mapped to output queue 5) for FCoE traffic on IEEE 802.1p priority 5:
   [edit class-of-service]
user@switch# set forwarding-classes class fcoe1 queue-num 5 no-loss

   
   

2. Configure the ingress classifier (fcoe_p5). The classifier maps the FCoE priority (code point 101) to the lossless FCoE forwarding class fcoe1:
   [edit class-of-service classifiers]
user@switch# set ieee-802.1 fcoe_p5 forwarding-class fcoe1 loss-priority low code-points 101

   
   

3. Apply the classifier to interfaces xe-0/0/25 and xe-0/026:
   [edit class-of-service]
user@switch# set interfaces xe-0/0/25 unit 0 classifiers ieee-802.1 fcoe_p5
user@switch# set interfaces xe-0/0/26 unit 0 classifiers ieee-802.1 fcoe_p5

   
   

4. Configure the CNP. The input stanza enables PFC on the FCoE priority (IEEE 802.1p code point 101), sets the MRU value (2240 bytes), and sets the cable length value (100 meters). The output stanza configures flow control on output queue 5 on the FCoE priority:
   [edit class-of-service]
user@switch# set congestion-notification-profile fcoe_p5_cnp input ieee-802.1 code-point 101 pfc mru 2240
user@switch# set congestion-notification-profile fcoe_p5_cnp input cable-length 100
user@switch# set congestion-notification-profile fcoe_p5_cnp output ieee-802.1 code-point 101 pfc flow-control-queue 5

   
   

5. Apply the CNP to the interfaces:
   [edit class-of-service]
user@switch# set interfaces xe-0/0/25 congestion-notification-profile fcoe_p5_cnp
user@switch# set interfaces xe-0/0/26 congestion-notification-profile fcoe_p5_cnp

   
   

6. Configure the DCBX application for FCoE to map to the Ethernet interfaces, so that DCBX can exchange application protocol TLVs on the IEEE 802.1p priority 5 instead of on the default priority 3:
   [edit]
user@switch# set applications application fcoe_p5_app ether-type 0x8906

   
   

7. Configure a DCBX application map to map the FCoE application to the correct IEEE 802.1p FCoE priority:
   [edit]
user@switch# set policy-options application-maps fcoe_p5_app_map application fcoe_p5_app code-points 101

   
   

8. Apply the application map to the Ethernet interfaces so that DCBX exchanges FCoE application TLVs on the correct code point:
   [edit]
user@switch# set protocols dcbx interface xe-0/0/25 application-map fcoe_p5_app_map
user@switch# set protocols dcbx interface xe-0/0/26 application-map fcoe_p5_app_map

   
   

Verification

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

• Verifying the Forwarding Class Configuration
• Verifying the Behavior Aggregate Classifier Configuration
• Verifying the PFC Flow Control Configuration (CNP)
• Verifying the Interface Configuration
• Verifying the DCBX Application Configuration
• Verifying the DCBX Application Map Configuration
• Verifying the DCBX Application Protocol Exchange Interface Configuration

Verifying the Forwarding Class Configuration

Purpose

Verify that the lossless forwarding class fcoe1 has been created.

Action

Forwarding class                       ID      Queue  Policing priority  No-Loss
  best-effort                          0         0         normal        Disabled
  fcoe                                 1         3         normal        Enabled
  no-loss                              2         4         normal        Enabled
  network-control                      3         7         normal        Disabled
  fcoe1                                4         5         normal        Enabled
  mcast                                8         8         normal        Disabled

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 classifier maps the forwarding classes to the correct IEEE 802.1p code points (priorities) and packet loss priorities.

Action

List the classifier configured to support lossless FCoE transport using the operational mode command show class-of-service classifier:

Classifier: fcoe_p5, Code point type: ieee-802.1, Index: 63065
  Code point         Forwarding class                    Loss priority
  101                fcoe1                               low         

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_p5 maps code point 101 (priority 5) to explicitly configured lossless forwarding class fcoe1 and a packet loss priority of low, and all other priorities to the best-effort forwarding class with a packet loss priority of high.

Verifying the PFC Flow Control Configuration (CNP)

Purpose

Verify that PFC is enabled on the correct input priority and that flow control is configured on the correct output queue in the CNP.

Action

Display the congestion notification profile using the operational mode command show class-of-service congestion-notification:

Name: fcoe_p5_cnp, Index: 12137
Type: Input
Cable Length: 100 m
  Priority     PFC          MRU
  000          Disabled 
  001          Disabled 
  010          Disabled 
  011          Disabled 
  100          Disabled       
  101          Enabled      2240 
  110          Disabled 
  111          Disabled 
Type: Output
  Priority     Flow-Control-Queues 
  101 
               5

Meaning

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

The fcoe_p5_cnp CNP input stanza shows that PFC is enabled on code point 101 (priority 5), the MRU is 2240 bytes, and the cable length is 100 meters. The CNP output stanza shows that output flow control is configured on queue 5 for code point 101 (priority 5).

Verifying the Interface Configuration

Purpose

Verify that the correct classifier and congestion notification profile are configured on the interfaces.

Action

List the ingress interfaces using the operational mode commands show configuration class-of-service interfaces xe-0/0/25 and show configuration class-of-service interfaces xe-0/0/26:

congestion-notification-profile fcoe_p5_cnp;
unit 0 {
    classifiers {
        ieee-802.1 fcoe_p5;
    }
}

congestion-notification-profile fcoe_p5_cnp;
unit 0 {
    classifiers {
        ieee-802.1 fcoe_p5;
    }
}

Meaning

Both the show configuration class-of-service interfaces xe-0/0/25 command and the show configuration class-of-service interfaces xe-0/0/26 command show that the congestion notification profile fcoe_p5_cnp is configured on each interface, and that the IEEE 802.1p classifier associated with each interface is fcoe_p5.

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:

application fcoe_p5_app {
    ether-type 0x8906;

Meaning

The show applications configuration mode command shows all of the configured applications. The output shows that the application fcoe_p5_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:

fcoe_p5_app_map {
    application fcoe_p5_app code-points 101;
}

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_p5_app_map consists of the application named fcoe_p5_app, which is mapped to IEEE 802.1p code point 101.

Verifying the DCBX Application Protocol Exchange Interface Configuration

Purpose

Verify that the application map is applied to the correct interfaces.

Action

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

interface xe-0/0/25.0 {
    application-map fcoe_p5_app_map;
}
interface xe-0/0/26.0 {
    application-map fcoe_p5_app_map;
}

Meaning

The show protocols dcbx configuration mode command lists the application map association with interfaces. The output shows that interfaces xe-0/0/25.0 and xe-0/0/26.0 use application map fcoe_p5_app_map.