Show mac address of a cisco switch interface
![show mac address of a cisco switch interface show mac address of a cisco switch interface](https://i.stack.imgur.com/9quEJ.png)
According the table, frames for this destination should be sent to “16.0.14”. So for example, let’s zoom in on the MAC address . VLAN MAC Address Type age Secure NTFY Ports/ * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MACĪge - seconds since last seen,+ - primary entry using vPC Peer-Link, Let’s have a look at a specific entry in the MAC address table of a Nexus 7000: N7K-1-pod5# show mac address-table dynamic vlan 100 I created a very simple FabricPath network and performed a couple of pings to generate some MAC address table entries. So I decided to get into the lab and see if I could find some commands that would help me establish the relation between the LID and the outbound interface on the edge switch.
![show mac address of a cisco switch interface show mac address of a cisco switch interface](https://image.slidesharecdn.com/lab-viewtheswitchmacaddresstablelab-viewtheswitch-211012103542/85/lab-view-the-switch-mac-address-table-lab-view-the-switch-3-320.jpg)
For the switch sending to the MAC address it represents the egress port at the destination edge switch). (The interface represented by the LID is an ingress interface from the perspective of the edge switch that inserts the LID into the outer source address. For the N7K, the Cisco Live presentation states that the LID maps to the “port index” of the ingress interface. Apparently, the Nexus 5000 and Nexus 7000 engineering teams did not talk to each other to agree on some consistent method of assigning the LIDs, but each created their own platform-specific implementation.įor the N5K I couldn’t really find more than that the LID will usually be 0, but there may be some exceptions.
#Show mac address of a cisco switch interface how to
As such, it is up to the implementation to determine how to derive a unique LID to represent its ports.
![show mac address of a cisco switch interface show mac address of a cisco switch interface](https://media.fs.com/images/ckfinder/ftp_images/tutorial/a-switch-with-3-computers-around.jpg)
The acronym LID stands for “Local ID” and, as the name implies, it has local significance to the switch that a particular MAC address resides on. Inside this presentation I found a somewhat cryptic sentence that states “for N7K the LID is the port index of the ingress interface, for N5K LID most of the time will be 0”. I found some hints in the excellent Cisco Live Presentation BRKDCT-3313 – Fabric Path operation and troubleshooting (2013 London). So I decided to dig in and see if I could find out a bit more about the way LIDs are used on the Nexus switches. However, the method by which these LIDs are derived doesn’t seem to be very well documented and this had been bugging me for a while. The SWID represents the switch-ID of the remote FabricPath edge switch, the SSID represents the sub-switch ID (which is only used in vPC+) and the LID represents the outbound port on the remote edge switch. When a FabricPath edge switch needs to send a frame to a remote MAC address, it performs a MAC address table lookup and finds an entry of the form.