Monday , October 15 2018
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QinQ termination on subinterfaces to support DHCP Relay

So far you have learned basic and selective QinQ on Huawei swiches. They seem like a simple Layer 2 VPN solution, which we can use to connect 2 or more offices. And of course, it is truth.

But, sometimes, we want to have an access to external services or just to the Internet, instead of connecting 2 branch offices. And, still we can use QinQ technology, why not?

The only thing we should do is to terminate QinQ VLAN Tag on a router. Just create L3 subinterface and let the router to use IP routing table to forward packets.

In our LAB, I am going to show you how to terminate QinQ to use DHCP server, located outside our network. In this case DHCP Relay feature must be used.

So let’s get to the point!

QinQ termination on subinterfaces to support DHCP Relay on Huawei

Topology of QinQ to support DHCP Relay

QinQ VLAN Tag termination on Huawei

1. Configure the basic Layer 2 forwarding function

SW_1
vlan batch 100
#
interface Ethernet0/0/1
 port link-type access
 port default vlan 100
#
interface GigabitEthernet0/0/1
 port link-type trunk
 port trunk allow-pass vlan 100

SW2
vlan batch 200
#
interface Ethernet0/0/1
 port link-type access
 port default vlan 200
#
interface GigabitEthernet0/0/2
 port link-type trunk
 port trunk allow-pass vlan 200

2. Configure QinQ on SW_A and set packets sent from SW_1 and SW_2 to DHCP server to carry double tags

SW_A
#
interface GigabitEthernet0/0/1
 qinq vlan-translation enable
 port hybrid untagged vlan 1000
 port vlan-stacking vlan 100 stack-vlan 1000
#
interface GigabitEthernet0/0/2
 qinq vlan-translation enable
 port hybrid untagged vlan 1000
 port vlan-stacking vlan 200 stack-vlan 1000
#
interface GigabitEthernet0/0/3
 port link-type trunk
 port trunk allow-pass vlan 1000

3. Configure subinterfaces for QinQ VLAN tag termination on the DHCP-Relay router

#
interface GigabitEthernet0/0/0.1
 qinq termination pe-vid 1000 ce-vid 100
 ip address 172.16.1.1 255.255.255.0 
 arp broadcast enable
#
interface GigabitEthernet0/0/0.2
 qinq termination pe-vid 1000 ce-vid 200
 ip address 172.16.2.1 255.255.255.0 
 arp broadcast enable

4. Configure DHCP Relay function on Huawei

[DHCP-Relay]dhcp enable

[DHCP-Relay]interface GigabitEthernet0/0/0.1
[DHCP-Relay-GigabitEthernet0/0/0.1]dhcp select relay
[DHCP-Relay-GigabitEthernet0/0/0.1]dhcp relay server-ip 192.168.1.100

[DHCP-Relay]interface GigabitEthernet0/0/0.2
[DHCP-Relay-GigabitEthernet0/0/0.1]dhcp select relay
[DHCP-Relay-GigabitEthernet0/0/0.1]dhcp relay server-ip 192.168.1.100

5. Set IP address for communication between DHCP-Relay and DHCP-Server

[DHCP-Relay]interface GigabitEthernet0/0/1
[DHCP-Relay-GigabitEthernet0/0/1]ip address 192.168.1.1 255.255.255.0

6. DHCP Server configuration

dhcp enable
#
ip pool 1
 gateway-list 172.16.1.1 
 network 172.16.1.0 mask 255.255.255.0 
#
ip pool 2
 gateway-list 172.16.2.1 
 network 172.16.2.0 mask 255.255.255.0 
#
interface GigabitEthernet0/0/1
 ip address 192.168.1.100 255.255.255.0 
 dhcp select global

7. Configure static route to reach VLAN 100 and VLAN 200

[DHCP-Server]ip route-static 172.16.1.0 255.255.255.0 192.168.1.1
[DHCP-Server]ip route-static 172.16.2.0 255.255.255.0 192.168.1.1

8. DHCP verification

[DHCP-Relay]dis dhcp relay all
 DHCP relay agent running information of interface GigabitEthernet0/0/0.1 :
 Server IP address [01] : 192.168.1.100
 Gateway address in use : 172.16.1.1
 
 DHCP relay agent running information of interface GigabitEthernet0/0/0.2 :
 Server IP address [01] : 192.168.1.100
 Gateway address in use : 172.16.2.1

9. QinQ verification

And finally, after QinQ VLAN Tag termination, we have pure IP packet without any tag:

One comment

  1. I configured as per given instruction.. but not working.. getting no packets for the “dis dhcp relay stat”

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