The Cisco Nexus 2000 Series Fabric Extender has the following configuration guidelines and limitations:
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Before converting a port from trunk to FEX fabric, remove/unconfigure any explicit native VLAN configuration.
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Beginning with Cisco NX-OS Release 9.3(1), all FEX types support for N9K-C93360YC-FX2 switch in straight-through mode.
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Beginning with Cisco NX-OS Release 9.2(3), FEX supports IEEE 802.1X port-based authentication on FEX-ST and host interface
(HIF) ports. IEEE 802.1X port-based authentication support applies to both straight-through and dual-homed FEX.
For more information about configuring port-based authentication, see the Cisco Nexus 9000 Series NX-OS Security Configuration Guide, Release 9.x.
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Beginning with Cisco NX-OS Release 9.2(1), all FEX types support for the N9K-C93180YC-FX and N9K-C93108TC-FX switches in dual-homed
mode.
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Beginning with Cisco NX-OS Release 9.2(1), all FEX types support for the N9K-C93240YC-FX2 and N9K-C9336C-FX2 switches in straight-through
mode.
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Beginning with Cisco NX-OS Release 9.2(1), FCoE over FEX is supported on N9K-C93180YC-FX switches in both straight-through
and dual-homed mode with N2K-C2348UPQ, N2K-C2232PP, N2K-B22IBM-P and N2K-B22HP-P FEX models.
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Beginning with Cisco NX-OS Release 9.2(1), NetFlow for FEX Layer 3 ports is now supported on Cisco Nexus 9300-EX and 9300-FX
platform switches.
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The configuration is purged when:
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Converting from an active-active to straight-through or a straight-through to active-active FEX topology with Cisco Nexus
9000 Series switches requires reloading the parent switch. See also: https://bst.cloudapps.cisco.com/bugsearch/bug/CSCve15816
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While the FEX is online: the FEX goes down as a dual-homed FEX on conversion and comes back up a straight-through FEX. The
configuration is purged on bring up.
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While the FEX is offline: the FEX goes down as a dual-homed FEX, then the no vpc id command is entered on the fabric port channel. No configuration purge takes place. In this scenario, default the configuration
on FEX interfaces while toggling the mode from active-active to straight-through.
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ASCII/POAP Replay are supported from Release 7.0(3)I7(1) onwards. Earlier releases require manually reapplying the FEX configuration
after the FEX is online.
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An upgrade performed via install all command for Release 7.0(3)I2(2b) to Release 7.0(3)I6(2) or to Release 7.0(3)I7(x) and later may result in the VLANs being
unable to be added to the existing FEX HIF trunk ports. To recover from this, the following steps should be performed after
all FEXs have come online and the HIFs are operationally up:
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The 2332TQ FEX now supports Cisco Nexus 9300, 9300-EX, and 9500 platform switches as the parent switch (on all FEX supported
platforms).
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Beginning with Cisco NX-OS Release 9.2(1), FEX is supported on Nexus 9500 chassis with N9K-X9432PQ, N9K-X9536PQ, and N9k-X9636PQ
linecards in breakout mode.
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The default port mode is Layer 2.
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You can configure a maximum of eight ports as part of a fabric port channel (the uplink from the Fabric Extender to the switch).
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The Fabric Extender is supported with Cisco Nexus 9500 Series switches and X9464PX and X9564PX line cards and with Cisco
Nexus 9372PX and 9396PX switches.
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The Fabric Extender is supported on the N9K-C93108TC-EX, N9K-C93180LC-EX, N9K-C93180YC-EX, N9K-C93180YC-FX, and N9K-C93108TC-FX
switches. Support includes straight-through and dual-homed (active-active) FEX topologies.
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The 2348TQ-E Fabric Extender is supported.
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You can configure the Fabric Extender host interfaces as edge ports only. The interface is placed in an error-disabled state
if a downstream switch is detected.
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When you connect a FEX to a Cisco Nexus 9000 series device, the queuing capability on the FEX host interface is limited. A
router that is connected to a Layer 2 (using SVI interfaces) cannot participate in routing protocol adjacency. The FEX cannot
be used as a peer because when congestion occurs on the FEX host interface, the control plane traffic is not prioritized.
This limitation also applies to the FEX when it is connected to other Layer 3 devices, such as an ASA firewall, an ACE load
balancer, or other Layer 3 networking devices that are running a dynamic routing protocol. Static routes to routers, ASA firewalls,
ACE load balancers, and other Layer 3 network devices are supported.
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For FEX HIF port channels, Cisco recommends that you enable STP port type edge using the spanning tree port type edge [trunk ] command.
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If you configure the FEX with speed 100/full-duplex and you do not explicitly configure the neighboring device with speed 100/full-duplex, the data packets might not pass properly even though the link may appear as being "up".
Interface Configuration
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Description
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no speed
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Autonegotiates and advertises all speeds (only full duplex).
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speed 100
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Does not autonegotiate; pause cannot be advertised.
The peer must be set to not autonegotiate (only 100 Mbps full duplex supported).
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speed 1000
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Autonegotiates and advertises pause (advertises only for 1000 Mbps full duplex).
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Cisco Nexus 2332TQ, 2348TQ, 2348TQ-E, and 2348UPQ support 40G connectivity or 4x10G breakout.
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Cisco Nexus 2248PQ, 2348TQ, 2348TQ-E, 2332TQ, and 2348UPQ support 4x10g breakout on N9K-C93180YC-EX, N9K-C93180YC-FX, and
N9K-C93240YC-FX2.
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Cisco Nexus 2348TQ, 2332TQ, 2348TQ-E, and 2348UPQ support native 40G connectivity on N9K-C9332PQ, N9K-C93180YC-EX, N9K-C93108TC-EX,
N9K-C93180YC-FX, N9K-C93108TC-FX, N9K-C93240YC-FX2, and N9K-C9336C-FX2.
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For FEX support on various hardware platforms, see the FEX matrix at the location: https://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/nexus9000/hw/interoperability/fexmatrix/fextables.html
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FEX supports in-service software upgrades (ISSU) on the following switches when only in straight-through mode:
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In-service software upgrade (ISSU) is not supported on Cisco Nexus 9000 Series switches with dual-homed FEX.
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Beginning Cisco NX-OS Release 9.3(1), MTU 9216 is made default for FEX fabric ports-channels. Only MTU 9216 is allowed to
be configured on FEX fabric port-channels. Configuring any other value will throw an error.
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If the MTU value on a FEX fabric port-channel was set to 9216 before upgrading to Cisco NX-OS Release 9.3(1), the show running
config command will not display the MTU config as it is the new default in Cisco NX-OS Release 9.3(1). Due to this the show
running-config diff command displays the difference which is expected.
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A jumbo ping (greater than MTU 2344) from a switch supervisor to a FEX host fails because the control queue on a FEX supports
an MTU 2344 maximum.
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Layer 3 is supported on FEX interfaces and subinterfaces on Cisco Nexus 9300 Series switches.
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Layer 3 is supported on FEX port channel interfaces on Cisco Nexus 9300 Series switches.
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Layer 3 routing is supported on FEX interfaces, subinterfaces, and port-channel interfaces on Cisco Nexus 9300-EX, N9K-C93180YC-FX,
and N9K-C93240YC-FX2 platform switches.
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The following limitations apply to Layer 3 support on FEX interfaces for all platforms:
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FEX Layer 3 is not supported on Cisco Nexus 9500 Series switches.
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FEX Layer 3 is not supported on port channel subinterfaces.
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FEX Layer 3 does not support HSRP, ACLs, QoS, BFD, or DHCP on FEX Layer 3 ports and subinterfaces.
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FEX Layer 3 supports only 1500 bytes MTU.
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PIM is supported on FEX Layer 3 interfaces.
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Layer 3 and FEX consistency-checker does not support Layer 3 HIF ports
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Layer 3 is not supported on AA FEX interfaces
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Static routes and all routing protocols are supported on FEX Layer 3 ports.
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When connecting a FEX module to a 9300-EX Series switch, the switch queuing policy must be changed from 8Q to 4Q if QOS queuing
is going to be utilized.
Configuration Example:
switch(config)# system qos
switch(config-sys-qos)# service-policy type queuing out default-out-policy