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:
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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
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
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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