Suppress Fib Pending; Fex Group Gir Functionality - Cisco Nexus 5600 Series Configuration Manual

Configuring GIR (Cisco NX-OS Release 7.3(0)N1(1))

Suppress FIB Pending

The Suppress Forwarding Information Base (FIB) Pending feature uses the Border Gateway Protocol-Routing
Information Base (BGP-RIB) and the Enhanced Interior Gateway Routing Protocol-Routing Information Base
(EIGRP-RIB) feedback mechanism to avoid premature route advertisements and subsequent packet loss in a
network. This mechanism is enabled by default and ensures that routes are installed locally before they are
advertised to a neighbor.
BGP and EIGRP wait for feedback from RIB indicating that the routes that EIGRP or BGP installed in the
RIB are installed in the FIB before EIGRP or BGP sends out updates to the neighbors. EIGRP or BGP will
send out updates of only those routes that have versions up to the version that FIB has installed. This selective
update ensures that EIGRP or BGP does not send out premature updates resulting in attracting traffic even
before the data plane is programmed after a switch reload, line card reload, or when the switch moves to
normal mode from maintenance mode.

FEX Group GIR Functionality

You can use GIR to perform maintenance and software upgrade of the Cisco Nexus 5000, 5500 and 6000
Series switches and the connected FEXs in a dual homed vPC topology. A FEX group is a logical grouping
of FEXs. A FEX group is added to optimize the procedure to bring up or take down the FEX.
Consider a scenario (refer figure below) where there are 2 FEX groups, FG1 and FG2 in a VPC domain.
Assuming all hosts are redundantly connected, one leg is connected to one of the FEXs of FG1 and the other
leg is connected to one of the FEXs of FG2. Before putting the "secondary" switch in maintenance mode,
bring down FG1 to force all FEXs in FG1 to upgrade to newer version of image and establish connection to
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