This document provides instructions and configuration examples for setting up DHCP relay using Cisco Application Centric Infrastructure (ACI) and on Linux and Windows DHCP servers. It discusses creating DHCP relay policies and providers in ACI, as well as configuring DHCP scopes, pools, and options on Linux and Windows servers. Packet captures are shown to analyze DHCP option 82 for link selection. The document also lists useful ACI commands for verifying the DHCP configuration and troubleshooting.

1. ACI DHCP Config Guide
2017.04.04
Cisco Systems Korea
DC CSE / Woo Hyung Choi (whchoi@cisco.com)

2. ACI Topology for DHCP Relay
EPG :
11
BD : 1
VRF : 1
Tenant-DHCP-TEST
EPG:
1
VLAN 131 VLAN 132
BD : 11
EPG :
12
BD : 2
VRF : 2
192.168.2.1/24
EPG:
2
VLAN 133 VLAN 134
BD : 12
Tenant-Common
BD : DHCP
VRF : DHCP
192.168.111.1/24
EPG:
DHCP
VLAN 135
1.X Client 11.X Client 2.X Client 12.X Client
192.168.1.1/24 192.168.11.1/24 192.168.12.1/24
FABRIC-INFRA
TENANT DHCP ACCESS
Global DHCP ACCESS
LINUX (.254)
DHCP SERVER
W2K16 (.33)
DHCP SERVER

3. #1. Global DHCP ACCESS config – Create DHCP Relay Policy
1 Fabric – Access Policies
Global Policies – DHCP Relay Policies
2 Create DHCP Relay Policy
- "Name & Providers" configuration.
3 DHCP Provider
- DHCP EPG Mapping
- Setting the DHCP EP address
1
2
3

4. #1. Global DHCP ACCESS config – Create DHCP Relay Label
1 Tenant – “Tenant using DHCP” –
Networking – BD – DB using DHCP
- DHCP Relay Label
2 Create DHCP Relay Label
- “DHCP Relay Label” config

5. #2. TENANT Based DHCP Config - Create DHCP Relay Policy
1 Tenants – Common – “BD for DHCP”
– DHCP Relay Lable – Create DHCP
Relay Label
2 Create DHCP Relay Lable
- Select Tenant
3 Create DHCP Relay Policy Profile
- Create DHCP-TENANT name
- Creating a Provider
1
2
3
3

6. #2. TENANT Based DHCP Config - Create DHCP Relay Label
1 Tenants – Common – “BD for DHCP”
– DHCP Relay Lable – Create DHCP
Relay Label
2 Create DHCP Relay Lable
- Select Tenant
- Selecting the DHCP Profile
Generated by Common Tenant
1 2
3 Networking – Protocol Polices –
DHCP – Relay Policies
- Verify that the Relay Policy has
been created

7. Window 2016 server based – Packet dump (bootp.dhcp)
W2K16 DHCP SERVER DHCP CLIENT
DHCP Option 82
Bootp Flag

8. Window 2016 server based -DHCP Window 2016 Config Guide
1 Verifying the Windows Server 2016
Version
(OS Build – 14393.969)
2 Superscope Config
- Address Pool (DHCP IP range)
- Address Lease
(Verify DHCP address assignment)
- Scope Option (Router, DNS Option)
1
2

9. Linux Server Based- Packet dump (bootp.dhcp)
W2K16 DHCP SERVER DHCP CLIENT
DHCP Option 82

10. Linux server based -DHCP Config Guide
1 dhcpd install (ISC)
2 dhcpd interface config
root@LNX-DHCP:~# apt-get install isc-dhcp-server
root@LNX-DHCP:~# vim /etc/default/isc-dhcp-server
…..
INTERFACES="eth0“
…..

11. Linux server based -DHCP Config Guide
3 dhcpd config
root@LNX-DHCP:~# vim /etc/dhcp/dhcpd.conf
#default-lease-time : IP address lease time to client.
#max-lease-time :
default-lease-time 600;
max-lease-tiem 7200;
# Set Subnet and Netmask
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.11 192.168.1.100;
option domain-name-servers 8.8.8.8;
option domain-name "cisko-dc.com';
option routers 192.168.1.1;
option broadcast-address 192.168.0.255;
}

12. Linux server based -DHCP Config Guide
4 DHCP Option 82 Link Selection Configuration for Recognition
root@LNX-DHCP:~# vim /etc/dhcp/dhcpd.conf
ignore client-updates;
authoritative;
stash-agent-options true;
#Option 82 link-selection enable
option agent.link-selection ip-address;
option routers 192.168.111.254;
#동일서브넷 DHCP 설정
subnet 192.168.111.0 netmask 255.255.255.0{
option routers 192.168.111.1;
option subnet-mask 255.255.255.0;
pool {
range 192.168.111.11 192.168.11.20;
}
#DHCP Relay DHCP configuration - 4 BD, 4 subnet configuration example.
class "BD-1Net" {
match if(binary-to-ascii(10, 8, ".", option agent.link-selection) = "192.168.1.0");
}
shared-network BD-1Net {
subnet 192.168.1.0 netmask 255.255.255.0 {
option routers 192.168.1.1;
option subnet-mask 255.255.255.0;
pool {
allow members of "BD-1Net";
range 192.168.1.101 192.168.1.110;
}
}
}

13. Linux server based -DHCP Config Guide
4 DHCP Option 82 Link Selection Configuration for Recognition
shared-network BD-2Net {
subnet 192.168.2.0 netmask 255.255.255.0 {
option routers 192.168.2.1;
option subnet-mask 255.255.255.0;
pool {
allow members of "BD-2Net";
range 192.168.2.101 192.168.2.110;
}
}
}
shared-network BD-11Net {
subnet 192.168.11.0 netmask 255.255.255.0 {
option routers 192.168.11.1;
option subnet-mask 255.255.255.0;
pool {
allow members of "BD-11Net";
range 192.168.11.101 192.168.11.110;
}
}
}
shared-network BD-12Net {
subnet 192.168.12.0 netmask 255.255.255.0 {
option routers 192.168.12.1;
option subnet-mask 255.255.255.0;
pool {
allow members of "BD-2Net";
range 192.168.12.101 192.168.12.110;
}
}
}
5 DHCP Server restart
service isc-dhcp-server restart

14. Linux server based - Verify IP assignment.
1 DHCP Server check
more /var/lib/dhcp/dhcpd.lease

15. Useful ACI Commands to Verify DHCP Configuration
1 Verifying the DHCP Configuration on the LEAF
LEAF-101# show ip dhcp relay
2 https://apic/visore.html
dhcpRelayP, dhcpRsProv, dhcpProvDhcp,
dhcpRtLblDefToRelayP