- Edge device: This device performs layer 2 activities (to the internal network) and OTV transportation to the other site(s).
- Transport network: This is the network (can be layer 3) that connects all the sites. This is your WAN connection, possible managed by your service provider.
- Join interface: This is the uplink interface on the edge device that is connected to the transport network.
- Internal interface: This is the interface on the edge device that is connected to the internal network.
- Overlay interface: This is a logical interface, with support for multi access, multicast. This interface encapsulates layer 2 frames in IP headers (also ‘MAC routing’)
- Overlay network: A logical network that connects all sites together and uses MAC routing for interconnecting the sites.
- Site: Your (layer 2) network on a location. In most cases, this is one of your datacenters.
Cisco published a configuration guide for connecting a Nexus 2248TP FEX to a Nexus 7000. I’ll explain the configuration process to configure the FEX for basic connectivity.
A FEX is a Nexus 2000 series switch. In a very high level explanation, this switch is a switchport module in a separate 1U chassis, which is configured and controlled from a Nexus 5000/7000. There is 1 drawback: the switchports on the FEX can only be used for host ports. It’s not possible to connect other switches to a FEX port because of the fact that BPDUguard is enabled by default. It’s not possible to disable BPDUguard. Switchports on the FEX can be used for layer 2 and layer 3 connections. For more information about the FEX itself I’ll refer to this link
All configuration is done on the Nexus 7000 with NX-OS 6.0(1). In this scenario, the 2248TP FEX is connected to switchport ethernet 1/1 (10GE port) of the Nexus 7000 with a twinax cable.
switch(config)# int ethernet 1/1 switch(config-if)# switchport mode fex-fabric Error: feature-set fex is not enabled
switch(config)# install feature-set fex switch(config)# feature-set fex