When using an 802.1qtunnel does the number of CE-VLAN's pushed across the tunnel increase the frame size, or can i push as many inner vlan tags through without increasing the header size?
Form our testing every extra CE vlan added to a tunnel requires an extra 4 bytes added to the MTU to allow the traffic to flow.
Every tunnel adds 4 bytes to Ethernet frame.
BR, A.C.
Do you mean every VLAN adds 4 bytes to the frame?
No, every tunnel adds 4 bytes to the frame.
Nope
assuming you use 802.1Q format packets (there is a cisco specific vlan flavour which is more complicated and that adds more overhead).
when you use 1 "layer" of vlan tags, you have 12 bits of vlan numbers you can use - you get approx 4000 vlans to work with, although some cisco setups will limit you to around 1000.
you can use more than 1 "layer" of vlans on a single packet.
eg if you take a carrier ethernet service, you might get a WAN ethernet interface with several vlans, each of which acts as a link to a different remote site, and inside that tunnel you can use your own vlans.
So 1 vlan tag on the packet used to tell the service provider where to send the packet, 1 customer vlan tag within that to select your target vlan, and inside that the meat of a normal Ethernet packet.
Total of 2 vlan tags per packet, 4 bytes overhead for each.
If you are getting more overhead than that something is set up wrong.
i suggest you get hold of a packet sniffer and see what is actually going out in the packets
Good luck
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