Per VLAN DHCP server with a Cisco Catalyst 3560 -- Comment monter un serveur DHCP par VLAN avec un commutateur Cisco Catalyst 3560

posted Mar 29, 2011, 8:39 PM by Olivier Diotte   [ updated Apr 9, 2011, 1:58 PM ]
So a friend and I are setting up our school department's internal network (EDIT 2011/04/09: As part of a student project). We wanted to use layer 3 switches as DHCP servers (because we could and because we wanted).

The idea was somewhat simple: each VLAN gets its own DHCP pool from the core switch.
Since each VLAN was unique on their access switch (no 2 VLAN would access the network via the same access switch),
we initially came to the conclusion we needed to set the core switch's downstream port as an access port in the same VLAN.
Obviously we were wrong (that would have been stupid anyway since it goes against Cisco's Hierarchical Network Design recommendations). (Hierarchical Network Design)

Just set an interface vlan ip address on the Core switch (in the same subnet as the DHCP pool). Make the link between core and access a trunk.
It Just Works© (see attached Packet Tracer file).

Cisco Catalyst 3560 switches are. too. damn. powerful.
Olivier Diotte,
Mar 29, 2011, 9:06 PM