The command show fex reveals that our new FEX is undergoing a software upgrade.
#Vss cisco mac address flapping upgrade#
If all goes well, the 5000 should take control of the 2000 and upgrade the FEX's software to match itself if necessary. This is actually all that's needed to associate a Nexus 2000 with its parent 5000. Switch(config-if)# switchport mode fex-fabric We configure the port-channel interface to operate in FEX-fabric mode, and then associate the attached FEX by assigning it a number between 100 and 199: The third mode enables fabric extension to a Nexus 2000. You should already be familiar with the first two modes. Nexus Ethernet interfaces can operate in one of three modes: access, trunk, or FEX-fabric. Switch(config-if-range)# channel-group 101 There's nothing new about this configuration, however it is worth noting that a port-channel configured for fabric extension cannot run LACP. Since we're using two 10 Gbps Ethernet links to attach the FEX, we'll configure them as a single 20 Gbps port-channel.
![vss cisco mac address flapping vss cisco mac address flapping](https://community.cisco.com/kxiwq67737/attachments/kxiwq67737/6016-discussions-lan-switching-routing/305716/1/flapping_issue.jpg)
When the FEX is physically connected, the Nexus 5500 should automatically detect its presence even before the interfaces have been provisioned: Nexus 5500 Configurationīefore beginning, ensure that the FEX feature is enabled with the command show feature.
#Vss cisco mac address flapping how to#
With that said, let's look at how to connect a Nexus 2200 to a Nexus 5500. This may or may not be a problem, depending on your oversubscription rates and latency requirements. This looks great on paper, however the major drawback is that Nexus 2000s don't do any local switching: A packet from port 1 on a 2000 to port 2 on the same switch must travel up to the 5000 and back.
![vss cisco mac address flapping vss cisco mac address flapping](https://community.cisco.com/kxiwq67737/attachments/kxiwq67737/5931-discussions-network-management/113138/1/mac_flap_all_ports.png)
The intended datacenter design is to deploy many Nexus 2000s as top-of-rack (ToR) switches and connect them back to Nexus 5000s at the end or middle of the row. This is very similar in concept to stacking Catalyst 2960S or 3750 switches, except that the 2000s are connected to a 5000 via 10 Gbps Ethernet rather than via a proprietary (and short) stacking cables. For example, port 8 on FEX 101 is referred to as Ethernet101/1/8 on the 5000. All interface configuration is performed on the Nexus 5000, where every attached Nexus 2000 is treated as an individual slot. Today's lab involved attaching a Nexus 2200 fabric extender, or FEX, to a Nexus 5500.įor those unfamiliar with this setup, a Nexus 2000 is essentially a standalone line module: It requires connectivity to a Nexus 5000 switch to function. In preparation for a major datacenter deployment, I've been re-familiarizing myself with Cisco's Nexus platform (and naturally, what I pick up on the job will make its way onto the blog).