Linkinga chassis to two fabric port channel port groups is disruptive and does not affect the VIF namespace
unlessit is manually acknowledged. The VIF namespace is then automatically set to the smaller size fabric
portchannel port group usage (either 63 or 118 VIFs) of the two groups.
Caution
Forhigh availability cluster mode applications, symmetric cabling configurations are strongly recommended.
Ifthe cabling is asymmetric, the maximum number of VIFs available is the smaller of the two cabling
configurations.
Formore information on the maximum number of VIFs for your Cisco UCS environment, see the configuration
limitsdocument for yourhardware andsoftware configuration.
Proper FEX and Fabric Interconnect Port Connectivity
Thefollowing illustrations are for example only; you do not need to skip available ports to provide future
expansionroom. Seethe UCSManager configuration guide for FI port configuration considerations and
limitations.
Note
Observethe following guidelines:
•Whenyou connect the server chassis to the fabric interconnect, do not connect the FEXes to the fabric
interconnect’sexpansion modules. While similar in appearance to the other ports on the fabric interconnect,
theexpansion modules are never used for direct chassis connections. They are typically used for SAN
connectivityor network uplink.
•Allports of a FEX must be connected to only one fabric interconnect. Youmust connect each fabric
interconnectto the chassisthrough itsown FEX.
•Ifyou need to connectto a second fabric interconnect, do the following:
◦Thechassis must have a second FEX installed.
◦Allports of the second FEX must be connected to the second fabric interconnect only because the
FEXis a fabric extender, which can only be connected to a single switch, or in this case, a fabric
interconnect.
Cisco UCS 5108 Server Chassis Installation Guide
48 OL-20035-05
Installation
Proper FEX and Fabric Interconnect Port Connectivity