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Tag Stacking Change

Tag Stacking Change. Authors:. Date: 2013-09-10. Abstract.

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Tag Stacking Change

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  1. Tag Stacking Change Authors: • Date:2013-09-10 Norman Finn, Cisco Systems

  2. Abstract • Work now in progress on P802.1Qbz and P802.11ak has shown that the method currently defined in IEEE 802.1Q for adding and removing tags (e.g., the VLAN tag) to frames on LLC media (e.g., 802.11) is untenable. A new scheme is proposed in P802.1Qbz Draft 1.3 for use by P802.11ak. In the worst case, this change could invalidate a currently-compliant implementation of 802.11. This presentation solicits comments from any organization or individual that might be affected by this change. Norman Finn, Cisco Systems

  3. References • A more complete version of this presentation is document 11-13/0952r2. • The current text of P802.1Qbz Draft 1.3 contains this new tag stacking scheme. P802.1Qbz has passed Task Group Ballot with no “Disapprove” votes. Norman Finn, Cisco Systems

  4. End-to-end tag stacking todayAll tags must be translated at once by B3 B1 B2 B3 B4 B5 E1 E2 Length/Type encodingon L/T media LLC encodingon LLC media BA BA L/T LLC I I CA CA CA CA L/T L/T LLC LLC CA S S S S CA L/T L/T LLC LLC LLC Q Q Q Q Q L/T L/T L/T LLC LLC LLC data data data data data data 802.1Q decoder ring: BA = Backbone Addresses, I = I-tag, CA = Customer Addresses, S = Service VLAN tags, Q = Customer VLAN tags. Norman Finn, Cisco Systems

  5. The new end-to-end tag stacking methodOne translation per tag or media change B1 B2 B3 B4 B5 E1 E2 Length/Type encodingon L/T media LLC encodingon LLC media BA BA L/T LLC I I CA CA CA CA L/T L/T L/T LLC CA S S S S CA L/T L/T L/T L/T LLC Q Q Q Q Q L/T L/T L/T L/T L/T L/T data data data data data data 802.1Q decoder ring: BA = Backbone Addresses, I = I-tag, CA = Customer Addresses, S = Service VLAN tags, Q = Customer VLAN tags. Norman Finn, Cisco Systems

  6. Norman Finn, Cisco Systems Old and new tag stacking • NOW • All tags and original MSDU are LLC encoded • One bridge must fix all tags and orig. MSDU • Cannot introduce new end-to-end tags • Most frames 6 bytes longer per tag • NEW • First tag or MSDU is LLC and rest of frame is Length/Type • Each LLC bridge fixes one tag or MSDU • Can introduce new end-to-end tags • Most frames 6 bytes shorter per tag

  7. A plea • This example is from 802.11-2012 Table P-3. If you use this format, please tell 802.1 Interworking and/or 802.11 TGak, because we propose to remove this format from the standards; it stacks SNAP encodings: • (This frame would be encoded, in the new scheme as:) • If there is such a use, then we will have to re-examine our options. . 6 2 L 6 2 M EtherType SNAP Tag value SNAP EtherType data AA-AA-03-00-00-00 81-00 87-65 AA-AA-03-00-00-00 08-06 IP ARP packet . 6 2 L 2 M EtherType SNAP Tag value EtherType data AA-AA-03-00-00-00 81-00 87-65 08-06 IP ARP packet Slide 7 Norman Finn, Cisco Systems Norman Finn, Cisco Systems

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