[ixpmanager] IXPManager: Two customers on one port

[Nick Hilliard]

Salvador Bertenbreiter via ixpmanager wrote on 21/04/2026 23:57:
> Is the subinterface method a better method to replace fanout ports? If 
> so, would that run on any HW platform (Tomahawk-based switch for 
> example), or are more advanced ASICs like Jericho required? We also use 
> mainly Arista as our IXP switches.

Hi Salvador,

Just on that sample configuration that Barry posted:

> interface Ethernet25.2001
>    description Cust: Resold Customer 1 Ltd
>    encapsulation dot1q vlan 2001
>    vlan id 10

This configuration allows you to attach different incoming vlans to a 
single peering LAN, and also handles the case where ixp customer A on 
vlan 2001 wants to talk to ixp customer B on vlan 2002 on the same 
physical, but on the same LAN.  I.e. packets in and out on the same port 
- hence the "hair-pin" name.

In other words, this is not the same as defining two normal 
subinterfaces with different VLAN IDs.

There are limitations: the sflow vlan ID is the incoming vlan ID (i.e. 
2001) instead of the peering lan. There are also restrictions which 
apply to layer 2 ACLs.

Nick