System not getting up After configuring valid mac address and even on waiting 120 seconds.

[Anvesh-Kumar-Rayankula]

Steps:

1. Assign a valid MAC address xx:xx:xx:xx:xx:xx to the system using the curl command curl -k -H "X-Auth-Token:${bmc_token}" -X PATCH -D patch.txt -d '{"MACAddress":"xx:xx:xx:xx:xx:xx"}' https://$bmc/redfish/v1/Managers/bmc/EthrnetInterfaces/eth0
2. System stop pinging

Expectation:

Should not take more than 60 seconds for bring system to up After setting valid mac address

[Anvesh-Kumar-Rayankula]

@sunharis @raviteja-b

[prkatti1]

@Anvesh-Kumar-Rayankula How many minutes/seconds it is taking to come back or accessible?

[prkatti1]

Can you mention how much time we'll not be able access GUI, SSH & Redfish after changing MAC address?

[Anvesh-Kumar-Rayankula]

Taking above 3:30mints time during that time we not able to access GUI, SSH and redfish after changing MAC address

[mdmillerii]

Is this with static IP address or DHCP? IP v4 or v6? The test host in the same Ethernet (what os) or through a router from different subnet? (Changing the MAC requires a new ARP entry binding it to the IP to be required. If using DHCP you may get a new address assignment).

[prkatti1]

It was configured with static IPv4 address. When MAC address is modified, it should not take so much long time to respond to ping, SSH or Redfish commands.

[prkatti1]

3.5 minutes is very long time, we have not noticed such long time from inception.

[mdmillerii]

By the same reasoning, it's reasonable for an arp cache to remember this long, at least if it honors updates. A quick search shows Cisco ios defaults to 4 hours, while another source says 2 to 20 minutes. It really depends on the os running the test or the router configuration if on a different subnet. A gratuitous arp is often used to advertise a changed binding can be advertised with an address claim as in https://datatracker.ietf.org/doc/html/rfc4436#section-4.1