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

[Martin T]

Steinar, Arie:

thanks for confirming this! In addition, Cisco 3750 Metro series also
support custom S-tag TPID value on trunk ES ports with "switchport trunk
dot1q ethertype" command. "switchport trunk dot1q ethertype" affects all
the egress traffic, i.e. even single-tagged egress frames(
http://www.cloudshark.org/captures/27dfdd102ed7).


regards,
Martin

On Thu, Jan 2, 2014 at 6:34 AM, Arie Vayner (avayner) <avayner at cisco.com>wrote:

> Martin,
>
> From a quick check I could see support for both 802.1ad (0x88a8) and other
> custom S-tags (0x9100) on ASR9K. I can also see references on 7600 with ES+
> modules.
>
> Some references:
> https://supportforums.cisco.com/docs/DOC-15556
>
> http://www.cisco.com/en/US/docs/routers/asr9000/software/asr9k_r4.2/lxvpn/command/reference/b_lxvpn_cr42asr9k_chapter_01.html#wp1086679105
>
> http://www.cisco.com/en/US/products/ps9853/products_tech_note09186a0080c1d17b.shtml
>
> HTH
> Arie
>
>
> -----Original Message-----
> From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of
> sthaug at nethelp.no
> Sent: Wednesday, January 1, 2014 9:24 PM
> To: m4rtntns at gmail.com
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] Difference between Cisco Q-in-Q and IEEE 802.1ad
>
> > 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:
>
> Correct, it's 0x88a8 vs 0x8100 for the S-tag.
>
> > In addition, are there Cisco switches out there which use 0x88a8 as a
> > TPID value of S-tag by default?
>
> Don't know of any.
>
> > 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:
>
> Juniper E-series (ERX) routers use 0x9100 by default.
>
> Steinar Haug, Nethelp consulting, sthaug at nethelp.no_______________________________________________
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