Static mac address N7K

Ernesto Fernandez gomez-pinto · ‎04-18-2017

Hi,

I need configure a static mac address in N7K and i'm confused with the mode of working os Nexus 7K. I'm configured with "mac address-table static 00a6.ca00.1708 vlan 1708 interface port-channel203" and i can see work fine in the mac tables, but my surprise is when the interface port-channel 203 go down the mac address remain in mac table.

What sense can it have to keep a mac entry through a down interface?.

Regards.

Mark Malone · ‎04-18-2017

Hi Its a static mac it will always be in the table whether reachable or not because you manually created it , like a null route

There is no benefit to it but its not dynamic so it does not work the same and it will not remove itself like dynamic from the table when an interface goes down , once in cli it will be in the table until removed , if it removed itself it would need to be able to reapply itself when it came back up or your configuration would be void but if it was able to do that it would be dynamic anyway

Ernesto Fernandez gomez-pinto · ‎04-18-2017

Hi Mark,

"Hi Its a static mac it will always be in the table whether reachable or not because you manually created it , like a null route"

This is not exactly, because is platform dependant. For example, in N5K when interface go down the mac in table go to drop.

n5-del-lab(config)# mac address-table static 0101.0101.0101 vlan 3450 interface Ethernet100/1/5
n5-del-lab(config)# show mac address-table address 0101.0101.0101
Legend:
        * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC
        age - seconds since last seen,+ - primary entry using vPC Peer-Link
   VLAN     MAC Address      Type      age     Secure NTFY   Ports/SWID.SSID.LID
---------+-----------------+--------+---------+------+----+------------------
3450     0101.0101.0101    user      0          F    F Eth100/1/5
n5-del-lab(config)# int ethernet 100/1/5
n5-del-lab(config-if)# sh
n5-del-lab(config-if)# show mac address-table address 0101.0101.0101
Legend:
        * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC
        age - seconds since last seen,+ - primary entry using vPC Peer-Link
   VLAN     MAC Address      Type      age     Secure NTFY   Ports/SWID.SSID.LID
---------+-----------------+--------+---------+------+----+------------------
3450     0101.0101.0101    user      0          F    F drop
n5-del-lab(config-if)# no sh
n5-del-lab(config-if)# show mac address-table address 0101.0101.0101
Legend:
        * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC
        age - seconds since last seen,+ - primary entry using vPC Peer-Link
   VLAN     MAC Address      Type      age     Secure NTFY   Ports/SWID.SSID.LID
---------+-----------------+--------+---------+------+----+------------------
3450     0101.0101.0101    user      0          F    F Eth100/1/5

Regards.

Mark Malone · ‎04-18-2017

Hi

That's odd because it should be retaining it as per official doc

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/configuration/guide/cli/CLIConfigurationGuide/MACAddress.html#pgfId-1129904

You can also enter a MAC address, which is termed a static MAC address, into the table. These static MAC entries are retained across a reboot of the switch.

..Its still retained in running config correct ?