Cliche time – You learn something new every day…
… and today I learned about how the seconds elapsed field in DHCP packets can affect the DHCP DORA (Discover/Offer/Request/Acknowledgement) process – particularly when using a load-balance failover config on Microsoft DHCP servers.
- 2 Microsoft DHCP servers with DHCP scopes setup for load-balance (50/50)
- Meraki APs
- AP Management VLAN gateway configured on core Nexus switch (and branch routers) with one IP helper address pointed towards DHCP server 1 (This will be important)
- Greenfield wireless deployment
Some (but not all) new Meraki APs were not getting DHCP IP addresses when they got plugged into the network.
I love troubleshooting DHCP because it is a straightforward, structured process.