How to stop duplication of traffic to different vlans in the same VPLS instance (For ADPC cards)

VPLS traffic destined to one particular vlan under a VPLS instance, can be duplicated to all other vlans and on different interfaces, on the same vpls instance.

This behaviour was found only in DPC cards. When tested on MPC cards the traffic destined for one particular vlan was not duplicated to other vlans

  • This is an expected behaior for a BUM traffic (Broadcast, Unknown-unicast and Multicast)
  • But on the DPC cards even for an known unicast traffic the duplication issue was seen.
  • Say, If we have 400 vlans under same VPLS instance and a unicast traffic destined to one vlan is getting duplicated to all the 400 vlans, resulting in interface over-subscrioption.
  • This is seen only for DPC cards.

This is the default behaviour of the DPC cards.
If we configure the VPLS instance with “vlan-id” command and use one vlan then we dont see this behavior.
But, if we use one VPLS instance for sending multiple vlan traffic then we need the below knob.
Solution is to configure the knob “no-local-switching” under the VPLS instance
Configuration of the router below :

Interface stats when traffic destined only for vlan 3000 and its getting duplicated to all the other interfaces in vpls instance
After configuring the Knob “no-local-switching”  , the traffic destined for vlan 3000 was not getting duplicated to other vlans.
Interface stats after configuring the knob “no-local-switching”

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James Palmer

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