[Enterprise Switch ] Hot to verify specific QinQ Follow
1. Input Pkts without any VLAN tag in downlink port , then this Pkts with double-tag in uplink port
2. Selective QinQ is an advanced VLAN tagging feature used in service provider (SP) networks to efficiently encapsulate and forward customer VLAN traffic. It is an enhancement of the standard QinQ (802.1ad) technology.
Brief Introduction:
Selective QinQ allows a switch to encapsulate customer VLAN (C-VLAN) traffic with a service provider VLAN (S-VLAN) tag based on specific criteria—such as VLAN ID, MAC address, or IP address—instead of tagging all incoming traffic on a port uniformly.
Basic Concept:
- Standard QinQ: All traffic entering a port is tagged with the same S-VLAN.
- Selective QinQ: Only traffic that matches specific conditions (e.g., a certain VLAN ) is encapsulated, while other traffic is left unchanged or handled differently
Case 1 :
case 1 (example : verify DHCP option 82 can work with double-tag):
input DHCP discovery pkts on port1 without tag , to sniffer egress Pkts on port 2 , check this Pkts with double-tag (C-tag 101 , S-tag 200)and include option 82 msg .
Key config on switch :
vlan database
VLAN 1 name DefaultVlan media ethernet
vlan 101,200 media ethernet
!
interface ethernet 1/1
switchport allowed vlan add 200 untagged
switchport native vlan 200
switchport dot1q-tunnel vlan-double-tag cvid 101
!
interface ethernet 1/2
switchport allowed vlan add 200 double-tagged
ip dhcp snooping trust
!
ip dhcp snooping
ip dhcp snooping vlan 200
ip dhcp snooping information option
!
Testing result :
- Pkts with double-tag , S-tag 200 , C-tag 101
2. And it include option 82 msg :
It’s correct
case 2 (verify DHCP packets can work with double-tag from uplink to downlink):
input DHCP pkts on port2 with double-tag , to sniffer egress Pkts on port 1 , check this Pkts without tag .
key configs : the same as case 1
except result & actually result :
the dhcp pkts without tag .
It’s correct
case 3 (replace feature : convert specific single tag to double vlan-tag from downlink to uplink):
testing topology :
Key config on switch :
dot1q-tunnel system-tunnel-control
!
vlan database
VLAN 1 name DefaultVlan media ethernet
vlan 100,200,300 media ethernet
!
interface ethernet 1/1
switchport allowed vlan add 100,200 untagged
switchport dot1q-tunnel mode access
switchport dot1q-tunnel service 100 match cvid 200 replace cvid 300
!
interface ethernet 1/2
switchport allowed vlan add 100 double-tagged
!
except result & actually result :
Pkts with Double-tag : SVID 100 , CVID 300 , result is correct .
case 4 (double vlan-tag become single-tag from uplink to downlink):
testing topology :
Key config on switch (the same case 3):
dot1q-tunnel system-tunnel-control
!
vlan database
VLAN 1 name DefaultVlan media ethernet
vlan 100,200,300 media ethernet
!
interface ethernet 1/1
switchport allowed vlan add 100,200 untagged
switchport dot1q-tunnel mode access
switchport dot1q-tunnel service 100 match cvid 200 replace cvid 300
!
interface ethernet 1/2
switchport allowed vlan add 100 double-tagged
!
except result & actually result :
Pkts with single-tag CVID 200 , result is correct .
Note :
- the testing DUT is ECS4150-54P V4.1.3.252
- replace feature : convert specific single tag to double vlan-tag from downlink to uplink
this only support for ECS4150-54P , no support for ECS4150-28P
It’s due to different chipset is different: 28 ports : AC5 ,54 ports :AC5X)
- IF DUT is ECS4120 , in case3 and case4 , The command is different in uplink port :
ECS4150-54P :
switchport allowed vlan add 100 double-tagged
ECS4120-28F :
switchport allowed vlan add 100 tagged
(Other cases , like case1 & case2 , the commands are the same in ECS4150 & ECS4120)
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