konfigurasi DHCP Server di switch Layer-3

Berikut cara konfigurasi DHCP Server di switch Layer-3 (Cisco) supaya PC di VLAN bisa dapat IP otomatis.

Contoh skenario

• VLAN 10 (USER) : 192.168.10.0/24 gateway 192.168.10.1
• VLAN 20 (HR) : 192.168.20.0/24 gateway 192.168.20.1
• Switch L3 jadi gateway + DHCP server

1) Buat VLAN & SVI (gateway) + aktifkan routing

conf t
ip routing

vlan 10
 name USER
vlan 20
 name HR

interface vlan 10
 ip address 192.168.10.1 255.255.255.0
 no shutdown

interface vlan 20
 ip address 192.168.20.1 255.255.255.0
 no shutdown
end

Cek:

show ip interface brief
show vlan brief

2) Set port user jadi access ke VLAN masing-masing

conf t
interface range fa0/1 - 12
 switchport mode access
 switchport access vlan 10
 spanning-tree portfast

interface range fa0/13 - 24
 switchport mode access
 switchport access vlan 20
 spanning-tree portfast
end

3) Konfigurasi DHCP (exclude + pool)

Exclude IP (biar tidak dipinjamkan DHCP)

conf t
ip dhcp excluded-address 192.168.10.1 192.168.10.20
ip dhcp excluded-address 192.168.20.1 192.168.20.20
end

Buat DHCP pool per VLAN

conf t
ip dhcp pool VLAN10-USER
 network 192.168.10.0 255.255.255.0
 default-router 192.168.10.1
 dns-server 8.8.8.8 1.1.1.1
 lease 7

ip dhcp pool VLAN20-HR
 network 192.168.20.0 255.255.255.0
 default-router 192.168.20.1
 dns-server 8.8.8.8 1.1.1.1
 lease 7
end
wr mem

4) Verifikasi DHCP bekerja

show ip dhcp pool
show ip dhcp binding
show ip dhcp server statistics
show running-config | section dhcp

Catatan penting (sering bikin gagal)

• Pastikan PC mendapat IP via DHCP (auto).
• Pastikan SVI up/up (SVI akan up kalau ada minimal 1 port VLAN itu yang up).
• Kalau DHCP server bukan di switch ini (mis. server terpisah), di SVI pakai:

  interface vlan 10
   ip helper-address <IP_DHCP_SERVER>
  

  (Kalau DHCP sudah di switch L3 yang sama, tidak perlu helper-address.)

Kalau kamu kasih model switch (mis. 3560/3750/3650/9300) + VLAN & subnet yang kamu pakai, aku bikinkan konfigurasi persis sesuai topologi kamu (termasuk trunk/uplink kalau ada).