Quick-Series 29 : Mx – Bridge-Domain – Using Vlan-id None ? –
Feb 26
Uncategorized bridge-domain, jncie, juniper, mx No Comments
Hi,
Continuing on Bridge-Domains on Mx, I came across using vlan-id “none” and initially was surprised by this knob, I mean we create bridge-domain based on a Vlan and associate / segregate traffic based on Vlan-id.
Lets explore a use case or a remote scenario where this might come in handy.
Let us say you have customers with different vlan’s and you are about to be in merger and provide a common Layer-3 IP. Obviously, if you are in a situation where you have them on your sub-interfaces, you cannot have same vlan-id for two Sub-interfaces.
Let see what Vlan-id None can do here
Looking closely at the configuration, we see that vlan-id none has been used instead of being specific, but as you see the interfaces, they are clearly in vlans 101 and 102. So, how does this work ?
There you go, there is a Pop in the inbound direction of the interface, a POP action popping out Vlan and the return traffic is now having PUSH action, hence traffic coming into bridge-domain will not care with what Dot1q tag the packet is coming-in.
Lets initiate a Ping and see if this works from two customer ends who are in different Vlans.
There you Go
Regards
Rakesh M