DHCP Relay Agent Over L3VPN Configuration

The DHCPClosed Dynamic Host Configuration Protocol Relay feature was designed to forward DHCP broadcast requests as unicast packets to a configured DHCP server or servers for redundancy. In the L3VPN case, there is a special tunnel which gets created through which all the communication happens. In OcNOS, the interface created is named as tunmpls. This tunnel name is not exposed to the OcNOS control plane.This interface is directly created in the kernel.

DHCP Relay Over L3 VPN for IPv4

Before configuring DHCP Relay, make sure DHCP server and client configurations are done.

Figure 33. DHCP Relay Over L3 VPN Configuration

DHCP Client

#configure terminal

Enter configure mode.

(config)#interface xe2

Enter interface mode.

(config-if)#ip address dhcp

Enable DHCP on interface

(config-if)#commit

Commit the candidate configuration to the running configuration

PE1 (DHCP Relay Agent)

#configure terminal

Enter configure mode.

(config)#ip dhcp relay

By default this will be enabled. It starts the ip dhcp relay service.

(config)#ip vrf vrf1

Configuring non default vrf vrf1

(config-vrf)#rd 10:10

Assign a route distinguisher to VRFClosed Virtual Routing and Forwarding

(config-vrf)#route-target both 10:10

Configure a route target for vrf1.

(config-vrf)#ip dhcp relay address 11.11.0.1

Configure DHCP server address.

(config-vrf)#ip dhcp relay uplink l3vpn

configure IPv4 DHCP Relay over L3VPN.

(config)#interface xe4

Enter interface mode.

(config-if)#ip vrf forwarding vrf1

Configure vrf forwarding for vrf1

(config-if)#ip address 50.50.50.1/24

Add IP address.

(config-if)#ip dhcp relay

Configure DHCP relay for the interface connecting to client.

(config-if)#commit

Commit the candidate configuration to the running configuration

(config-if)#exit

Exit from interface mode

(config)#interface lo

Enter interface mode

(config-if)#ip address 1.1.1.1/32 secondary

Set an IP address on the interface

(config-if)#commit

Commit the candidate configuration to the running configuration

(config-if)#exit

Exit from interface mode

(config)#router ldp

Enter the Router LDP mode.

(config-router)#router-id 1.1.1.1

Configure an LDP router ID.

(config-router)#exit

Exit from Router LDP mode

(config)#interface xe1

Enter interface mode

(config-if)#ip address 10.1.1.1/24

Add IP address.

(config-if)#label-switching

Enable label switching on the interface

(config-if)#enable-ldp ipv4

Enable IPv4 LDP configuration on the interface.

(config-if)#commit

Commit the candidate configuration to the running configuration

(config-if)#exit

Exit from interface mode

(config)#router ospf 100

Enter the Router OSPF mode.

(config-router)#network 1.1.1.1/32 area 0.0.0.0

Advertise loopback address in OSPF.

(config-router)#network 10.1.1.0/24 area 0.0.0.0

Advertise network address in OSPF.

(config-router)#exit

Exit Router OSPF mode and return to Configure mode.

(config)# router bgp 100

Enter the Router BGP mode, ASN: 100

(config-router)# bgp router-id 1.1.1.1

Configure a fixed Router ID (1.1.1.1)

(config-router)# neighbor 3.3.3.3 remote-as 100

Configuring PE2 as iBGP neighbor using it's loopback IP

(config-router)# neighbor 3.3.3.3 update-source lo

Source of routing updates as loopback

(config-router)# address-family ipv4 unicast

Entering into IPV4 unicast address family

(config-router-af)# neighbor 3.3.3.3 activate

Activate the neighbor in the IPV4 address family

(config-router-af)#exit

Exiting of Address family mode

(config-router)# address-family vpnv4 unicast

Entering into address family mode as vpnv4

(config-router-af)# neighbor 3.3.3.3 activate

Activate the neighbor in the vpnv4 address family

(config-router-af)#exit

Exiting of Address family mode

(config-router)# address-family ipv4 vrf vrf1

Entering into address family mode as ipv4 vrf vrf1

(config-router-af)# redistribute connected

Redistribute connected routes.

(config-router-af)#exit

Exiting of Address family mode

(config-router)# commit

Commit the candidate configuration to the running configuration

P

#configure terminal

Enter configure mode.

(config)#interface lo

Enter interface mode

(config-if)#ip address 2.2.2.2/32 secondary

Set an IP address on the interface

(config-if)#exit

Exit from interface mode

(config)#router ldp

Enter the Router LDP mode.

(config-router)#router-id 2.2.2.2

Configure an LDP router ID.

(config-router)#exit

Exit from Router LDP mode

(config)#interface xe14

Enter interface mode

(config-if)# ip address 20.1.1.1/24

Add IP address.

(config-if)# label-switching

Enable label switching on the interface

(config-if)# enable-ldp ipv4

Enable IPv4 LDP configuration on the interface.

(config-if)#exit

Exit from interface mode

(config)#interface xe1

Enter interface mode

(config-if)# ip address 10.1.1.2/24

Add IP address.

(config-if)# label-switching

Enable label switching on the interface

(config-if)# enable-ldp ipv4

Enable IPv4 LDP configuration on the interface.

(config-if)#exit

Exit from interface mode

(config)#router ospf 100

Enter the Router OSPF mode.

(config-router)#network 3.3.3.3/32 area 0.0.0.0

Advertise loopback address in OSPF.

(config-router)#network 20.1.1.0/24 area 0.0.0.0

Advertise network address in OSPF.

(config-router)#network 10.1.1.0/24 area 0.0.0.0

Advertise network address in OSPF.

(config-router)#exit

Exit Router OSPF mode and return to Configure mode.

(config)# commit

Commit the candidate configuration to the running configuration

PE2

#configure terminal

Enter configure mode.

(config)#ip vrf vrf1

Configuring non default vrf vrf1

(config-vrf)# rd 10:10

Assign a route distinguisher to VRF

(config-vrf)# route-target both 10:10

Configure a route target for vrf1.

(config)#interface xe48

Enter interface mode.

(config-if)#ip vrf forwarding vrf1

Configure vrf forwarding for vrf1

(config-if)# commit

Commit the candidate config

(config-if)#ip address 11.11.0.2/24

Add IP address.

(config-if)#exit

Exit from interface mode

(config)#interface lo

Enter interface mode

(config-if)#ip address 3.3.3.3/32 secondary

Set an IP address on the interface

(config-if)#exit

Exit from interface mode

(config)#router ldp

Enter the Router LDP mode.

(config-router)#router-id 3.3.3.3

Configure an LDP router ID.

(config-router)#exit

Exit from Router LDP mode

(config)#interface xe14

Enter interface mode

(config-if)# ip address 20.1.1.2/24

Add IP address.

(config-if)# label-switching

Enable label switching on the interface

(config-if)# enable-ldp ipv4

Enable IPv4 LDP configuration on the interface.

(config-if)#exit

Exit from interface mode

(config)#router ospf 100

Enter the Router OSPF mode.

(config-router)#network 3.3.3.3/32 area 0.0.0.0

Advertise loopback address in OSPF.

(config-router)#network 20.1.1.0/24 area 0.0.0.0

Advertise network address in OSPF.

(config-router)#exit

Exit Router OSPF mode and return to Configure mode.

(config)# router bgp 100

Enter the Router BGP mode, ASN: 100

(config-router)# bgp router-id 3.3.3.3

Configure a fixed Router ID (3.3.3.3)

(config-router)# neighbor 1.1.1.1 remote-as 100

Configuring PE1 as iBGP neighbor using it's loopback IP

(config-router)# neighbor 1.1.1.1 update-source lo

Source of routing updates as loopback

(config-router)# address-family ipv4 unicast

Entering into IPV4 unicast address family

(config-router-af)# neighbor 1.1.1.1 activate

Activate the neighbor in the IPV4 address family

(config-router-af)#exit

Exiting of Address family mode

(config-router)# address-family vpnv4 unicast

Entering into address family mode as vpnv4

(config-router-af)# neighbor 1.1.1.1 activate

Activate the neighbor in the vpnv4 address family

(config-router-af)#exit

Exiting of Address family mode

(config-router)# address-family ipv4 vrf vrf1

Entering into address family mode as ipv4 vrf vrf1

(config-router-af)# redistribute connected

Redistribute connected routes.

(config-router-af)#exit

Exiting of Address family mode

(config-router)# commit

Commit the candidate configuration to the running configuration

Validation

PE1 (DHCP Relay Agent)

Copy 
Use this for Command syntax, and Validation code snippets.

To use:
Insert this snippet where you want the code block to be.
Right click and select convert to text.
Copy the code you want to insert.
Right click on the block and select Edit Code Snippet to open the editor.
Paste the code and click OK in the bottom right.

Incoming DHCPv4 packets which already contain relay agent option are FORWARDED and changed.

Copy 
PE1#show ip dhcp relay address
VRF Name: vrf1
  DHCP Servers configured: 11.11.0.1

Incoming DHCPv4 packets which already contain relay agent option are FORWARDED and changed.

DHCP Client

Copy 
#show ip interface brief | include xe2
  xe5       *50.50.50.2      up         up

DHCP Relay Over L3 VPN for IPv6

Before configuring DHCP Relay, make sure DHCP server and client configurations are done.

Figure 34. DHCP Relay Over L3 VPN Configuration

DHCP Client

#configure terminal

Enter configure mode.

(config)#interface xe2

Enter interface mode.

(config-if)#ipv6 address dhcp

Enable DHCP on interface

(config-if)#commit

Commit the candidate configuration to the running configuration

PE1 (DHCP Relay Agent)

#configure terminal

Enter configure mode.

(config)#ipv6 dhcp relay

By default this will be enabled. It starts the ipv6 dhcp relay service.

(config)#ip vrf vrf1

Configuring non default vrf vrf1

(config-vrf)#rd 10:10

Assign a route distinguisher to VRF

(config-vrf)#route-target both 10:10

Configure a route target for vrf1.

(config-vrf)#ipv6 dhcp relay address 2002::1

Configure DHCP server address.

(config-vrf)#ipv6 dhcp relay uplink l3vpn

configure IPv6 DHCP Relay over L3VPN.

(config)#interface xe4

Enter interface mode.

(config-if)#ip vrf forwarding vrf1

Configure vrf forwarding for vrf1

(config-if)# ipv6 address 2001::1/64

Add IPv6 address.

(config-if)#ipv6 dhcp relay

Configure DHCP relay for the interface connecting to client.

(config-if)#exit

Exit from interface mode

(config)#interface lo

Enter interface mode

(config-if)#ip address 1.1.1.1/32 secondary

Set an IP address on the interface

(config-if)#exit

Exit from interface mode

(config)#router ldp

Enter the Router LDP mode.

(config-router)#router-id 1.1.1.1

Configure an LDP router ID.

(config-router)#exit

Exit from Router LDP mode

(config)#interface xe1

Enter interface mode

(config-if)# ip address 10.1.1.1/24

Add IP address.

(config-if)# label-switching

Enable label switching on the interface

(config-if)# enable-ldp ipv4

Enable IPv4 LDP configuration on the interface.

(config-if)#exit

Exit from interface mode

(config)#router ospf 100

Enter the Router OSPF mode.

(config-router)#network 1.1.1.1/32 area 0.0.0.0

Advertise loopback address in OSPF.

(config-router)#network 10.1.1.0/24 area 0.0.0.0

Advertise network address in OSPF.

(config-router)#exit

Exit Router OSPF mode and return to Configure mode.

(config)#router bgp 100

Enter the Router BGP mode, ASN: 100

(config-router)#bgp router-id 1.1.1.1

Configure a fixed Router ID (1.1.1.1)

(config-router)#neighbor 3.3.3.3 remote-as 100

Configuring PE2 as iBGP neighbor using it's loopback IP

(config-router)#neighbor 3.3.3.3 update-source lo

Source of routing updates as loopback

(config-router)#address-family ipv4 unicast

Entering into IPV4 unicast address family

(config-router-af)#neighbor 3.3.3.3 activate

Activate the neighbor in the IPV4 address family

(config-router-af)#exit

Exiting of Address family mode

(config-router)#address-family vpnv4 unicast

Entering into address family mode as vpnv4

(config-router-af)#neighbor 3.3.3.3 activate

Activate the neighbor in the vpnv4 address family

(config-router-af)#exit

Exiting of Address family mode

(config-router)#address-family vpnv6 unicast

Entering into address family mode as vpnv6

(config-router-af)#neighbor 3.3.3.3 activate

Activate the neighbor in the vpnv6 address family

(config-router-af)#exit

Exiting of Address family mode

(config-router)# address-family ipv4 vrf vrf1

Entering into address family mode as ipv4 vrf vrf1

(config-router-af)#redistribute connected

Redistribute connected routes.

(config-router-af)#exit

Exiting of Address family mode

(config-router)# address-family ipv6 vrf vrf1

Entering into address family mode as ipv6 vrf vrf1

(config-router-af)#redistribute connected

Redistribute connected routes.

(config-router-af)#exit

Exiting of Address family mode

(config-router)#commit

Commit the candidate configuration to the running configuration

P

#configure terminal

Enter configure mode.

(config)#interface lo

Enter interface mode

(config-if)#ip address 2.2.2.2/32 secondary

Set an IP address on the interface

(config-if)#exit

Exit from interface mode

(config)#router ldp

Enter the Router LDP mode.

(config-router)#router-id 2.2.2.2

Configure an LDP router ID.

(config-router)#exit

Exit from Router LDP mode

(config)#interface xe14

Enter interface mode

(config-if)#ip address 20.1.1.1/24

Add IP address.

(config-if)#label-switching

Enable label switching on the interface

(config-if)#enable-ldp ipv4

Enable IPv4 LDP configuration on the interface.

(config-if)#exit

Exit from interface mode

(config)#interface xe1

Enter interface mode

(config-if)#ip address 10.1.1.2/24

Add IP address.

(config-if)#label-switching

Enable label switching on the interface

(config-if)#enable-ldp ipv4

Enable IPv4 LDP configuration on the interface.

(config-if)#exit

Exit from interface mode

(config)#router ospf 100

Enter the Router OSPF mode.

(config-router)#network 3.3.3.3/32 area 0.0.0.0

Advertise loopback address in OSPF.

(config-router)#network 20.1.1.0/24 area 0.0.0.0

Advertise network address in OSPF.

(config-router)#network 10.1.1.0/24 area 0.0.0.0

Advertise network address in OSPF.

(config-router)#exit

Exit Router OSPF mode and return to Configure mode.

(config)# commit

Commit the candidate configuration to the running configuration

PE2

#configure terminal

Enter configure mode.

(config)#ip vrf vrf1

Configuring non default vrf vrf1

(config-vrf)#rd 10:10

Assign a route distinguisher to VRF

(config-vrf)#route-target both 10:10

Configure a route target for vrf1.

(config)#interface xe48

Enter interface mode.

(config-if)#ip vrf forwarding vrf1

Configure vrf forwarding for vrf1

(config-if)#commit

Commit the candidate config

(config-if)#ipv6 address 2002::2/64

Add IPv6 address.

(config-if)#exit

Exit from interface mode

(config)#interface lo

Enter interface mode

(config-if)#ip address 3.3.3.3/32 secondary

Set an IP address on the interface

(config-if)#exit

Exit from interface mode

(config)#router ldp

Enter the Router LDP mode.

(config-router)#router-id 3.3.3.3

Configure an LDP router ID.

(config-router)#exit

Exit from Router LDP mode

(config)#interface xe14

Enter interface mode

(config-if)#ip address 20.1.1.2/24

Add IP address.

(config-if)#label-switching

Enable label switching on the interface

(config-if)#enable-ldp ipv4

Enable IPv4 LDP configuration on the interface.

(config-if)#exit

Exit from interface mode

(config)#router ospf 100

Enter the Router OSPF mode.

(config-router)#network 3.3.3.3/32 area 0.0.0.0

Advertise loopback address in OSPF.

(config-router)#network 20.1.1.0/24 area 0.0.0.0

Advertise network address in OSPF.

(config-router)#exit

Exit Router OSPF mode and return to Configure mode.

(config)#router bgp 100

Enter the Router BGP mode, ASN: 100

(config-router)#bgp router-id 3.3.3.3

Configure a fixed Router ID (3.3.3.3)

(config-router)#neighbor 1.1.1.1 remote-as 100

Configuring PE1 as iBGP neighbor using it's loopback IP

(config-router)#neighbor 1.1.1.1 update-source lo

Source of routing updates as loopback

(config-router)#address-family ipv4 unicast

Entering into IPV4 unicast address family

(config-router-af)#neighbor 1.1.1.1 activate

Activate the neighbor in the IPV4 address family

(config-router-af)#exit

Exiting of Address family mode

(config-router)#address-family vpnv4 unicast

Entering into address family mode as vpnv4

(config-router-af)#neighbor 1.1.1.1 activate

Activate the neighbor in the vpnv4 address family

(config-router-af)#exit

Exiting of Address family mode

(config-router)#address-family vpnv6 unicast

Entering into address family mode as vpnv6

(config-router-af)#neighbor 1.1.1.1 activate

Activate the neighbor in the vpnv6 address family

(config-router-af)#exit

Exiting of Address family mode

(config-router)#address-family ipv4 vrf vrf1

Entering into address family mode as ipv4 vrf vrf1

(config-router-af)#redistribute connected

Redistribute connected routes.

(config-router-af)#exit

Exiting of Address family mode

(config-router)#address-family ipv6 vrf vrf1

Entering into address family mode as ipv6 vrf vrf1

(config-router-af)#redistribute connected

Redistribute connected routes.

(config-router-af)#exit

Exiting of Address family mode

(config-router)#commit

Commit the candidate configuration to the running configuration

Validation

PE1 (DHCP Relay Agent)

Copy 
PE1#show running-config dhcp
ip vrf vrf1
 ipv6 dhcp relay address 2002::1
 ipv6 dhcp relay uplink l3vpn
interface xe4
 ipv6 dhcp relay
 
PE1#show ipv6 dhcp relay
IPv6 DHCP relay service is Enabled.
VRF Name: vrf1
  Option 82: Enabled
  DHCPv6 Servers configured: 2002::1
  DHCPv6 IA_PD Route injection: Disabled
  Interface                Uplink/Downlink
  ---------                -------------
  xe4                      Downlink
  l3vpn                    uplink
PE1#show ip dhcp relay address
VRF Name: vrf1
  DHCPv6 Servers configured: 2002::1

DHCP Client

Copy 
#show ipv6 interface brief | include xe2
  xe5       *2001::200      up         up