Can a Cisco Catalyst 9300 Be Configured for DHCP?

The Cisco Catalyst 9300 series switches can indeed be configured for Dynamic Host Configuration Protocol (DHCP) services. They can operate as a DHCP Server to assign IP configurations to clients or as a DHCP Relay Agent to forward DHCP messages across network segments. This flexibility helps network administrators centralize IP address management directly on Catalyst 9300 switches, streamlining network setup and maintenance in enterprise and SMB environments.

What DHCP Features Does Cisco Catalyst 9300 Support?

Running Cisco IOS XE, Catalyst 9300 switches support:

• DHCP Server: Assign IP addresses from defined pools and manage leases directly on the switch.
• DHCP Relay Agent: Forward DHCP packets across VLANs/subnets using ip helper-address.
• DHCP Snooping: Blocks rogue DHCP servers and builds a binding table for security.
• Option 82 Insertion: Adds circuit-ID and remote-ID for client identification and policy control.
• Port-Based Address Allocation: Ensures consistent IPs per port regardless of device MAC.
• DHCPv6 Support: Supports DHCPv6 client, server, and relay for IPv6 networks.

How to Configure DHCP Server on Cisco Catalyst 9300

Here’s a step-by-step CLI guide:

Prerequisites:

• DHCP service is enabled by default (service dhcp).
• Ensure L3 reachability to DHCP pool subnets.

Configuration Steps:

Switch> enable
Switch# configure terminal

! Exclude static IPs
Switch(config)# ip dhcp excluded-address 192.168.1.1 192.168.1.10

! Create DHCP pool
Switch(config)# ip dhcp pool TEST
Switch(dhcp-config)# network 192.168.1.0 255.255.255.0
Switch(dhcp-config)# default-router 192.168.1.1
Switch(dhcp-config)# dns-server 8.8.8.8
Switch(dhcp-config)# lease 30

! Configure SVI with IP from pool
Switch(config)# interface vlan 1
Switch(config-if)# ip address 192.168.1.5 255.255.255.0
Switch(config-if)# no shutdown

Switch(config)# end
Switch# copy running-config startup-config

Verification:

View leases:

show ip dhcp binding

View pool stats:

show ip dhcp pool TEST

How to Configure DHCP Relay on Cisco Catalyst 9300

Use DHCP Relay when clients are in different VLANs/subnets from your DHCP server.

Configuration Steps:

Switch> enable
Switch# configure terminal

! Enable DHCP globally (default)
Switch(config)# service dhcp

! Configure SVI for client VLAN
Switch(config)# interface vlan 10
Switch(config-if)# ip address 192.168.10.1 255.255.255.0
Switch(config-if)# ip helper-address 192.168.20.1

! Ensure client ports are in the correct VLAN
Switch(config)# interface range gigabitethernet 1/0/1 - 24
Switch(config-if-range)# switchport mode access
Switch(config-if-range)# switchport access vlan 10

Switch(config)# end
Switch# copy running-config startup-config

Verification:

Debug DHCP relay:

debug ip dhcp server packet detail

Best Practices for DHCP on Cisco Catalyst 9300

• ✅ Exclude static IPs to avoid conflicts.
• ✅ Enable DHCP Snooping with trusted interfaces toward DHCP servers:

  ip dhcp snooping
  ip dhcp snooping vlan 10
  interface gigabitethernet 1/0/48
  ip dhcp snooping trust

• ✅ Use NTP for accurate lease timing.
• ✅ Backup the DHCP binding database for persistent IP tracking across reloads.

Related Questions (FAQ)

Q1: Can a Cisco Catalyst 9300 act as a DHCP server?
Yes. It can manage and assign IP addresses to clients from configured pools.

Q2: How to enable DHCP relay on Cisco 9300?
Enable service dhcp, then apply ip helper-address [DHCP Server IP] on the SVI of the VLAN where clients reside.

Q3: Can DHCP be configured on a switch?
Yes, Layer 3 switches like Catalyst 9300 can serve as DHCP servers or relay agents.

Q4: What is Cisco Catalyst 9300 used for?
Enterprise-grade secure Layer 3 access switching with high performance, advanced automation, and support for services like DHCP, NetFlow, and SD-Access.

Q5: Can a switch be a DHCP relay agent?
Yes, Catalyst 9300 can forward DHCP requests across subnets using relay functionality.

Conclusion

The Cisco Catalyst 9300 is fully capable of functioning as a DHCP server or relay agent, providing flexible, secure, and scalable IP management for enterprise networks. Mastering DHCP configurations on these switches can significantly simplify your network operations.