[c-nsp] Difference between Cisco Q-in-Q and IEEE 802.1ad

[Martin T]

Hi,

I need to check the transparency of a circuit for:

A) Cisco Q-in-Q frames
B) IEEE 802.1ad frames.


I made a simple setup where Cisco Q-in-Q port("switchport mode
dot1q-tunnel") was facing a laptop. Laptop was sending out frames with
802.1q tag(VID was 10) and Cisco Q-in-Q port pushed another 802.1q field.
Final frame can be seen here:
http://www.cloudshark.org/captures/ae485b68e9ed

Based on this Cisco Q-in-Q frame, the only difference between IEEE 802.1ad
frame and Cisco Q-in-Q frame is that former has 0x88a8 as an TPID value for
S-tag? I made a small illustration for this:

http://s17.postimg.org/m1hdy6r4v/Cisco_Qin_Q_VS_dot1ad.png


In addition, are there Cisco switches out there which use 0x88a8 as a TPID
value of S-tag by default? Last but not least, which devices use 0x9100 as
a TPID value for S-tags? According to drawing in Wikipedia IEEE 802.1ad
article, some do:
http://upload.wikimedia.org/wikipedia/commons/1/1b/TCPIP_802.1ad_DoubleTag.jpg



regards,
Martin