Cisco Nexus 5696Q Switch Configuration Guide

Cisco Nexus 5000 Series NX-OS Fibre Channel over Ethernet

Configuration Guide

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Text Part Number: OL-20924-01

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CONTENTS

Preface v

PREFACE

Audience v

Document Organization v

Document Conventions v

Related Documentation for Nexus 5000 Series NX-OS Software vii

Obtaining Documentation and Submitting a Service Request viii

New and Changed Information 1

CHAPTER 1

New and Changed Information 1

Overview 3

CHAPTER 2

Fibre Channel over Ethernet Overview 3

Configuring FCoE 5

CHAPTER 3

Information About FCoE 5

Information About FCoE and FIP 5

FCoE Initiation Protocol 5

FIP Virtual Link Instantiation 6

FCoE Frame Format 6

VLAN Tagging for FCoE Frames 6

FIP Ethernet Frame Format 6

Pre-FIP Virtual Link Instantiation 7

Information About DCBX 7

Data Center Bridging Exchange Protocol 7

DCBX Feature Negotiation 8

Lossless Ethernet 8

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Logical Link Up/Down 9

Converged Network Adapters 9

FCoE Topologies 10

Directly Connected CNA Topology 10

Remotely Connected CNA Topology 11

Fabric Extender Straight-Through and Host CNA Active-Active Topologies 12

FCoE Best Practices 13

Directly Connected CNA Best Practice 13

Remotely Connected CNA Best Practice 15

Licensing Requirements for FCoE 16

Guidelines and Limitations 16

Configuring FCoE 17

Configuring QoS 17

Enabling FCoE 18

Disabling FCoE 19

Disabling LAN Traffic on an FCoE Link 19

Configuring the FC-Map 20

Configuring the Fabric Priority 20

Configuring Jumbo MTU 21

Setting the Advertisment Interval 21

Verifying FCoE Configuration 22

Configuring FCoE VLANs and Virtual Interfaces 25

CHAPTER 4

Information About Virtual Interfaces 25

Guidelines for FCoE VLANs and Virtual Interfaces 25

Configuring Virtual Interfaces 26

Mapping a VSAN to a VLAN 26

Creating a Virtual Fibre Channel Interface 27

Associating a Virtual Fibre Channel Interface to a VSAN 29

Verifying the Virtual Interface 30

Mapping VSANs to VLANs Example Configuration 32

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Contents

Preface

This preface describes the audience, organization, and conventions of the Cisco Nexus 5000 Series NX-OS

Fibre Channel over Ethernet Configuration Guide. It also provides information on how to obtain related

documentation.

•Audience, on page v

•Document Organization, on page v

•Document Conventions, on page v

•Related Documentation for Nexus 5000 Series NX-OS Software, on page vii

•Obtaining Documentation and Submitting a Service Request, on page viii

Audience

This preface describes the audience, organization, and conventions of the . It also provides information on

how to obtain related documentation.

Document Organization

This document is organized into the following chapters:

DescriptionChapter

Describes the new and changed information for the new Cisco NX-OS

software releases.

New and Changed Information

Provides information about Fibre Channel over Ethernet (FCoE) and the

FCoE Initialization Protocol (FIP) and describes how to configure FCoE

on the Cisco Nexus 5000 Series switches.

Configuring FCoE

Describes how to configure Fibre Channel over Ethernet (FCoE) VLANs

and virtual interfaces on Cisco Nexus 5000 Series switches.

Configuring FCoE VLANs and

Virtual Interfaces

Document Conventions

Command descriptions use the following conventions:

Cisco Nexus 5000 Series NX-OS Fibre Channel over Ethernet Configuration Guide

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DescriptionConvention

Bold text indicates the commands and keywords that you enter literally

as shown.

bold

Italic text indicates arguments for which the user supplies the values.

Italic

Square brackets enclose an optional element(keyword or argument).[x]

Square brackets enclosing keywords or arguments separated by a vertical

bar indicate an optional choice.

[x | y]

Braces enclosing keywords or arguments separated by a vertical bar

indicate a required choice.

{x | y}

Nested set of square brackets or braces indicate optional or required

choices within optional or required elements. Braces and a vertical bar

within square brackets indicate a required choice within an optional

element.

[x {y | z}]

Indicates a variable for which you supply values, in context where italics

cannot be used.

variable

A nonquoted set of characters. Do not use quotation marks around the

string or the string will include the quotation marks.

string

Screen examples use the following conventions:

DescriptionConvention

Terminal sessions and information the switch displays are in screen font.screen font

Information you must enter is in boldface screen font.boldface screen font

Arguments for which you supply values are in italic screen font.italic screen font

Nonprinting characters, such as passwords, are in angle brackets.< >

Default responses to system prompts are in square brackets.[ ]

An exclamation point (!) or a pound sign (#) at the beginning of a line

of code indicates a comment line.

!, #

This document uses the following conventions:

Means reader take note. Notes contain helpful suggestions or references to material not covered in the manual.

Note

Means reader be careful. In this situation, you might do something that could result in equipment damage or

loss of data.

Caution

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Preface

Related Documentation for Nexus 5000 Series NX-OS Software

Cisco NX-OS documentation is available at the following URL:

http://www.cisco.com/en/US/products/ps9670/tsd_products_support_series_home.htmll

The documentation set for the Cisco Nexus 5000 Series NX-OS software includes the following documents:

Release Notes

•Cisco Nexus 5000 Series and Cisco Nexus 2000 Series Release Notes

•Cisco Nexus 5000 Series Switch Release Notes

Cisco Nexus 5000 Series NX-OS Configuration Guides

•Cisco Nexus 5000 Series NX-OS Fibre Channel over Ethernet Configuration Guide

•Cisco Nexus 5000 Series NX-OS Layer 2 Switching Configuration Guide

•Cisco Nexus 5000 Series NX-OS Quality of Service Configuration Guide

•Cisco Nexus 5000 Series NX-OS SAN Switching Configuration Guide

•Cisco Nexus 5000 Series NX-OS Security Configuration Guide

•Cisco Nexus 5000 Series NX-OS System Management Configuration Guide

•Cisco Nexus 5000 Series Switch CLI Software Configuration Guide

•Cisco Nexus 5000 Series Fabric Manager Configuration Guide, Release 3.4(1a)

Installation and Upgrade Guides

•Cisco Nexus 5000 Series Hardware Installation Guide

•Regulatory Compliance and Safety Information for the Cisco Nexus 5000 Series

Cisco NX-OS Command References

•Cisco Nexus 5000 Series Command Reference

Cisco NX-OS Technical References

•Cisco Nexus 5000 MIBs Reference

Cisco NX-OS Error and System Messages

•Cisco NX-OS System Messages Reference

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Preface

Related Documentation for Nexus 5000 Series NX-OS Software

Obtaining Documentation and Submitting a Service Request

For information on obtaining documentation, submitting a service request, and gathering additional information,

see the monthly What's New in Cisco Product Documentation, which also lists all new and revised Cisco

technical documentation, at:

http://www.cisco.com/en/US/docs/general/whatsnew/whatsnew.html

Subscribe to the What's New in Cisco Product Documentation as a Really Simple Syndication (RSS) feed

and set content to be delivered directly to your desktop using a reader application. The RSS feeds are a free

service and Cisco currently supports RSS version 2.0.

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Preface

Obtaining Documentation and Submitting a Service Request

CHAPTER 1

New and Changed Information

•New and Changed Information, on page 1

New and Changed Information

This chapter provides release-specific information for each new and changed feature in the Cisco Nexus 5000

Series NX-OS Fibre Channel over Ethernet Configuration Guide.

The latest version of this document is available at the following Cisco website:

http://www.cisco.com/en/US/products/ps9670/products_installation_and_configuration_guides_list.html

To check for additional information about Cisco NX-OS software, see the Cisco Nexus 5000 Series NX-OS

Release Notes available at the following Cisco website:

http://www.cisco.com/en/US/products/ps9670/prod_release_notes_list.html

Documentation Organization

As of Cisco NX-OS Release 4.1(3)N2(1), the Nexus 5000 Series configuration information is available in

new feature-specific configuration guides for the following information:

• System Management

• Layer 2 Switching

• SAN Switching

• Fibre Channel over Ethernet

• Security

• Quality of Service

The information in these new guides previously existed in the Cisco Nexus 5000 Series CLI Configuration

Guide which remains available on Cisco.com and should be used for all software releases prior to Cisco Nexus

5000 NX-OS Software Rel 4.1(3). Each new configuration guide addresses the features that are introduced

in or are available in a particular release. Select and view the configuration guide that pertains to the software

installed in your switch.

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The information in the new Cisco Nexus 5000 Series NX-OS Fibre Channel over Ethernet Configuration

Guide previously existed in Part 5: Fibre Channel over Ethernet of the Cisco Nexus 5000 Series CLI

Configuration Guide.

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New and Changed Information

CHAPTER 2

Overview

Cisco Nexus 5000 Series devices support the Fibre Channel over Ethernet features that are described in this

guide.

•Fibre Channel over Ethernet Overview, on page 3

Fibre Channel over Ethernet Overview

Fibre Channel over Ethernet (FCoE) allows Fibre Channel traffic to be encapsulated over a physical Ethernet

link. FCoE frames use a unique EtherType so that FCoE traffic and standard Ethernet traffic can be carried

on the same link.

Classic Ethernet is a best-effort protocol; in the event of congestion, Ethernet will discard packets, relying on

higher level protocols to provide retransmission and other reliability mechanisms. Fibre Channel traffic requires

a lossless transport layer; as a data storage protocol, it is unacceptable to lose a single data packet. Native

Fibre Channel implements a lossless service at the transport layer using a buffer-to-buffer credit system.

For FCoE traffic, the Ethernet link must provide a lossless service. Ethernet links on Cisco Nexus 5000 Series

switches provide two mechanisms to ensure lossless transport for FCoE traffic: link-level flow control and

priority flow control.

IEEE 802.3x link-level flow control allows a congested receiver to signal the far end to pause the data

transmission for a short period of time. The pause functionality is applied to all the traffic on the link.

The priority flow control (PFC) feature applies pause functionality to specific classes of traffic on the Ethernet

link. For example, PFC can provide lossless service for the FCoE traffic and best-effort service for the standard

Ethernet traffic. PFC can provide different levels of service to specific classes of Ethernet traffic (using IEEE

802.1p traffic classes).

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Overview

Fibre Channel over Ethernet Overview

CHAPTER 3

Configuring FCoE

This chapter describes how to configure Fibre Channel over Ethernet (FCoE) on Cisco Nexus 5000 Series

switches. It contains the following sections:

•Information About FCoE, on page 5

•FCoE Topologies, on page 10

•FCoE Best Practices, on page 13

•Licensing Requirements for FCoE, on page 16

•Guidelines and Limitations, on page 16

•Configuring FCoE, on page 17

•Verifying FCoE Configuration, on page 22

Information About FCoE

Fibre Channel over Ethernet (FCoE) provides a method of transporting Fibre Channel traffic over a physical

Ethernet connection. FCoE requires the underlying Ethernet to be full duplex and to provide lossless behavior

for Fibre Channel traffic.

Lossless behavior on Ethernet is provided by using a priority flow control (PFC) mechanism that prevents

packet loss during congestion conditions.

Note

Cisco Nexus 5000 Series switches support T11-compliant FCoE on all 10-Gigabit Ethernet interfaces.

Information About FCoE and FIP

FCoE Initiation Protocol

The FCoE Initialization Protocol (FIP) allows the switch to discover and initialize FCoE-capable entities that

are connected to an Ethernet LAN. Two versions of FIP are supported by the Cisco Nexus 5000 Series switch:

•FIP—The Converged Enhanced Ethernet Data Center Bridging Exchange (CEE-DCBX) protocol supports

T11-compliant Gen-2, Gen-3, and Gen-4 CNAs.

•Pre-FIP—The Cisco, Intel, Nuova Data Center Bridging Exchange (CIN-DCBX) protocol supports Gen-1

converged network adapters (CNAs).

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The Cisco Nexus 5000 Series switch detects the capabilities of the attached CNA and switches to the correct

FIP mode.

FIP Virtual Link Instantiation

Cisco NX-OS Release 4.1(3)N1(1) adds support for the T11-compliant FIP on the Cisco Nexus 5000 Series

switch.

FIP is used to perform device discovery, initialization, and link maintenance. FIP performs the following

protocols:

• FIP Discovery—When a FCoE device is connected to the fabric, it sends out a Discovery Solicitation

message. A Fibre Channel Forwarder (FCF) or a switch responds to the message with a Solicited

Advertisement that provides an FCF MAC address to use for subsequent logins.

•FCoE Virtual Link instantiation— FIP defines the encapsulation of fabric login (FLOGI) , fabric discovery

(FDISC), logout (LOGO), and exchange link parameters (ELP) frames along with the corresponding

reply frames. The FCoE devices use these messages to perform a fabric login.

• FCoE Virtual Link maintenance— FIP periodically sends maintenance messages between the switch

and the CNA to ensure the connection is still valid.

FCoE Frame Format

FCoE is implemented by encapsulating a Fibre Channel frame in an Ethernet packet with a dedicated Ethertype,

0x8906. That packet has a 4-bit version field. The other header fields in the frame (the source and destination

MAC addresses, VLAN tags, and frame markers) are all standard Ethernet fields. Reserved bits pad the FCoE

frame to the IEEE 802.3 minimum packet length of 64 bytes.

A Fibre Channel frame consists of 36 bytes of headers and up to 2112 bytes of data for a total maximum size

of 2148 bytes. The encapsulated Fibre Channel frame has all the standard headers, which allow it to be passed

to the storage network without further modification. To accomodate the maximum Fibre Channel frame in an

FCoE frame, the class-fcoe is defined with a default MTU of 2240 bytes.

VLAN Tagging for FCoE Frames

The Ethernet frames that are sent by the switch to the adapter may include the IEEE 802.1Q tag. This tag

includes a field for the class of service (CoS) value used by the priority flow control (PFC). The IEEE 802.1Q

tag also includes a VLAN field.

The Cisco Nexus 5000 Series switch expects frames from a FIP T11-compliant CNA to be tagged with the

VLAN tag for the FCoE VLAN. Frames that are not correctly tagged are discarded.

The switch expects frames from a pre-FIP CNA to be priority tagged with the FCoE CoS value. The switch

will still accept untagged frames from the CNA.

FIP Ethernet Frame Format

FIP is encapsulated in an Ethernet packet with a dedicated EtherType, 0x8914. The packet has a 4-bit version

field. Along with the source and destination MAC addresses, the FIP packet also contains a FIP operation

code and a FIP operation subcode. The following table describes the FIP operation codes.

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Configuring FCoE

FIP Virtual Link Instantiation

Table 1: FIP Operation Codes

FIP OperationFIP SubcodeFIP Operation Code

Discovery Solicitation0x010x0001

Discovery Advertisement0x02

Virtual Link Instantiation Request

0x010x0002

Virtual Link Instantiation Reply0x02

FIP Keep Alive

0x010x0003

FIP Clear Virtual Links0x02

FIP VLAN Request

0x010x0004

FIP VLAN Notification0x02

Pre-FIP Virtual Link Instantiation

Pre-FIP virtual link instantiation consists of two phases; link discovery using the Data Center Bridging

Exchange protocol (DCBX), which is followed by Fabric Login.

The Cisco Nexus 5000 Series switch is backward compatible with Gen-1 CNAs that operate in pre-FIP mode.

Pre-FIP is also known as the Cisco, Intel, Nuova Data Center Bridging Exchange (CIN-DCBX) protocol.

Note

Information About DCBX

Data Center Bridging Exchange Protocol

The Data Center Bridging Exchange (DCBX) protocol is an extension of the Link Layer Discovery Protocol

(LLDP). DCBX end points exchange request and acknowledgment messages. For flexibility, parameters are

coded in a type-length-value (TLV) format.

The Cisco Nexus 5000 Series switch supports two versions of DCBX:

• CEE-DCBX—The Converged Enhanced Ethernet DCBX is supported on all T11-compliant Gen-2,

Gen-3, and Gen-4 CNAs

•CIN-DCBX—The Cisco, Intel, Nuova DCBX is supported on Gen-1 converged network adapters (CNAs).

CIN-DCBX is used to perform link detection in addition to other functions.

DCBX runs on the physical Ethernet link between the Cisco Nexus 5000 Series switch and the CNA. By

default, DCBX is enabled on Ethernet interfaces. When an Ethernet interface is brought up, the switch

automatically starts to communicate with the CNA. If the CNA supports both CIN and CEE mode, the switch

and CNA will operate in CEE-DCBX mode.

During the normal operation of FCoE between the switch and the CNA, DCBX provides link-error detection.

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Configuring FCoE

Pre-FIP Virtual Link Instantiation

DCBX is also used to negotiate capabilities between the switch and the CNA and to send configuration values

to the CNA.

The CNAs that are connected to a Cisco Nexus 5000 Series switch are programmed to accept the configuration

values sent by the switch, allowing the switch to distribute configuration values to all attached CNAs, which

reduces the possibility of configuration errors and simplifies CNA administration.

DCBX Feature Negotiation

The switch and CNA exchange capability information and configuration values. The Cisco Nexus 5000 Series

switches support the following capabilities:

• FCoE—If the CNA supports FCoE capability, the switch sends the IEEE 802.1p CoS value to be used

with FCoE packets.

• Priority Flow Control (PFC)—If the adapter supports PFC, the switch sends the IEEE 802.1p CoS values

to be enabled with PFC.

• Priority group type-length-value (TLV)

• Ethernet logical link up and down signal

• FCoE logical link up and down signal for pre-FIP CNAs

The following rules determine whether the negotiation results in a capability being enabled:

• If a capability and its configuration values match between the switch and the CNA, the feature is enabled.

• If a capability matches, but the configuration values do not match, the following occurs:

• If the CNA is configured to accept the switch configuration value, the capability is enabled using

the switch value.

•If the CNA is not configured to accept the switch configuration value, the capability remains disabled.

• If the CNA does not support a DCBX capability, that capability remains disabled.

• If the CNA does not implement DCBX, all capabilities remain disabled.

The Cisco Nexus 5000 Series switch provides CLI commands to manually override the results of the PFC

negotiation with the adapter. On a per-interface basis, you can force capabilities to be enabled or disabled.

Note

The priority flow control (PFC) mode does not send PFC TLV and PFC will not negotiate between CNA and

Cisco Nexus 5000 Series switches.

Note

Lossless Ethernet

Standard Ethernet is a best-effort medium which means that it lacks any form of flow control. In the event of

congestion or collisions, Ethernet will drop packets. The higher level protocols detect the missing data and

retransmit the dropped packets.

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Configuring FCoE

DCBX Feature Negotiation

To properly support Fibre Channel, Ethernet has been enhanced with a priority flow control (PFC) mechanism.

Logical Link Up/Down

The following expansion modules provide native Fibre Channel ports to connect the Cisco Nexus 5000 Series

switch to other Fibre Channel devices.

• N5K-M1404 Cisco Nexus 5000 1000 Series Module 4x10GE 4xFC 4/2/1

• N5K-M1008 Cisco Nexus 5000 1000 Series Module 8xFC 4/2/1

• N5K-M1060 Cisco Nexus 5000 1000 Series Module 6xFC 8/4/2/1

On a native Fibre Channel link, some configuration actions (such as changing the VSAN) require that you

reset the interface status. When you reset the interface status, the switch disables the interface and then

immediately reenables the interface.

If an Ethernet link provides FCoE service, do not reset the physical link because this action is disruptive to

all traffic on the link.

The logical link up/down feature allows the switch to reset an individual virtual link. The logical link down

is signaled with a FIP Clear Virtual Link message.

For pre-FIP CNAs, the switch sends a DCBX message to request the CNA to reset only the virtual Fibre

Channel interface.

If the CNA does not support the logical link level up/down feature, the CNA resets the physical link. In this

case, all traffic on the Ethernet interface is disrupted.

DCBX-based FC Logical Link Status signaling only applies to FCoE sessions to pre-FIP CNAs.

Note

Converged Network Adapters

The following types of CNAs are available:

• Hardware adapter

•Works with the existing Fibre Channel host bus adapter (HBA) driver and Ethernet Network Interface

Card (NIC) driver in the server.

• Server operating system view of the network is unchanged; the CNA presents a SAN interface and

a LAN interface to the operating system.

• FCoE software stack

• Runs on existing 10-Gigabit Ethernet adapters.

Two generations of CNAs are supported by the Cisco Nexus 5000 Series switch:

• A FIP adapter uses the FIP to exchange information about its available capabilities and to negotiate the

configurable values with the switch.

• A pre-FIP adapter uses DCBX to exchange information about its available capabilities and to negotiate

the configurable values with the switch.

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Configuring FCoE

Logical Link Up/Down

To reduce configuration errors and simplify administration, the switch distributes the configuration data to

all the connected adapters.

FCoE Topologies

Directly Connected CNA Topology

The Cisco Nexus 5000 Series switch can be deployed as a Fibre Channel Forwarder (FCF) as shown in the

following figure.

Figure 1: Directly Connected Fibre Channel Forwarder

The following rules are used to process FIP frames to avoid the FCF being used as a transit between an FCoE

node (ENode) and another FCF. These rules also prevent login sessions between ENodes and FCFs in different

fabrics.

•FIP solicitation and login frames received from the CNAs are processed by the FCF and are not forwarded.

• If an FCF receives solicitations and advertisements from other FCFs over an interface, the following

occurs:

• The frames are ignored and discarded if the FC-MAP value in the frame matches the value of the

FCF (the FCF is in the same fabric)

• The interface is placed in the "FCoE Isolated" state if the FC-MAP value in the FIP frame does not

match that of the FCF (the FCF is in a different fabric)

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Configuring FCoE

FCoE Topologies

CNAs cannot discover or login to FCFs that are reachable only through a transit Cisco Nexus 5000 Series

FCF. The Cisco Nexus 5000 Series switch cannot perform the FCoE transit function between a CNA and

another FCF due to hardware limitations.

Because the Cisco Nexus 5000 Series FCF cannot perform the transit FCoE function, you must design your

network topology so that the active STP path of FCoE VLANs is always over the directly connected links

between the CNA and the FCF. Make sure that you configure the FCoE VLAN on the directly connected

links only.

Remotely Connected CNA Topology

The Cisco Nexus 5000 Series switch can be deployed as a Fibre Channel Forwarder (FCF) for remotely

connected CNAs, but not as a FIP Snooping Bridge, as shown in the following figure.

Figure 2: Remotely Connected Fibre Channel Forwarder

The following rules are used to process FIP frames to avoid the FCF being used as a transit between an ENode

and another FCF. These rules also prevent login sessions between ENodes and FCFs in different fabrics.

•FIP solicitation and login frames received from the CNAs are processed by the FCF and are not forwarded.

• If an FCF receives solicitations and advertisements from other FCFs over an interface, the following

occurs:

• The frames are ignored and discarded if the FC-MAP value in the frame matches the value of the

FCF (the FCF is in the same fabric)

• The interface is placed in the "FCoE Isolated" state if the FC-MAP value in the FIP frame does not

match that of the FCF (the FCF is in a different fabric)

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Configuring FCoE

Remotely Connected CNA Topology

Because the Cisco Nexus 5000 Series FCF cannot perform the transit FCoE function, you must design your

network topology so that the active STP path of FCoE VLANs is always over the directly connected links

between the CNA and the FCF. Make sure that you configure the FCoE VLAN on the directly connected

links only.

Fabric Extender Straight-Through and Host CNA Active-Active Topologies

Host Interfaces (HIFs) on fabric extender connections to servers in a port channel are supported in the regular

non-vPC fabric extender topology and both the fabric extender straight-through and fabric extender active-active

(A-A) topologies.

Cisco NX-OS supports FCOE only on straight-through topologies. The following figure shows the two fabric

extenders in a straight-through topology. Cisco NX-OS does not support FCoE over A-A fabric extender

HIFs.

Host CNAs can be dually homed in A-A mode to fabric extender HIFs, and the fabric extender should be in

straight-through mode.

Only vPCs are supported across the HIFs to host CNAs . Cisco NX-OS does not support downlink server

vPCs to host CNAs and fabric extender vPCs in A-A mode together.

Figure 3: Fabric Extender Straight-Through Topology

The following figure shows the two fabric extenders in a fabric extender A-A topology.

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Configuring FCoE

Fabric Extender Straight-Through and Host CNA Active-Active Topologies

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