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Base Protocol Document: Possible -05 to -06 Changes

Base Protocol Document: Possible -05 to -06 Changes. Donald Eastlake 3 rd +1-508-786-7754 Donald.Eastlake@motorola.com. Potential Changes in -06. Update the Pseudo-Code to correspond to the rest of the -05 draft and other changes adopted. Other possible changes:

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Base Protocol Document: Possible -05 to -06 Changes

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  1. Base Protocol Document:Possible -05 to -06 Changes Donald Eastlake 3rd +1-508-786-7754 Donald.Eastlake@motorola.com Base Protocol Future (v2)

  2. Potential Changes in -06 • Update the Pseudo-Code to correspond to the rest of the -05 draft and other changes adopted. • Other possible changes: • Eliminate the TRILL Header “M” (Multi-destination) bit. • Change inner VLAN tag to an S-tag. • Zero configuration alternative tree roots. • “Error” Messages. Base Protocol Future (v2)

  3. Update the Pseudo-Code • The pseudo-code is essentially unchanged from -04 to -05 while the text was changed as described in another presentation. • Update pseudo-code to correspond to the text. • Update pseudo-code to incorporate other changes. • Make pseudo-code more detailed and rigorous. Base Protocol Future (v2)

  4. Eliminate the “M” Bit • Currently the “M” or “multi-destination” bit in the TRILL Header means that the “egress RBridge nickname” field is actually the root of the distribution tree. • This is logically unnecessary: • M = 0 only for known unicast and core IS-IS frames. • M = 1 for all other frames Base Protocol Future (v2)

  5. Eliminate the “M” Bit (cont.) • Core IS-IS frames are identified by an inner DA of All-Rbridges with no inner VLAN tag. Thus you can always tell if something is a core IS-IS frame without the M bit. • Unicast is identified by a unicast inner DA. The only question is how to tell known unicast from unknown unicast. Base Protocol Future (v2)

  6. Eliminate the “M” Bit (cont.) • TRILL Header field V = 0, according to protocol draft -05, indicates core IS-IS, known unicast, or unanalyzed IP based multicast.V = 1 indicates per VLAN IS-IS, broadcast, unknown unicast, or IP based multicast that should be pruned on VLAN only. • So • (V = 0) and (core IS-IS or inner DA unicast)=> M = 0 • Otherwise M = 1 Base Protocol Future (v2)

  7. Inner VLAN tag -> S-Tag • The current protocol specification requires that the inner VLAN tag be a Q-Tag (official a “C-Tag” now). S-Tag is more expressive for QoS. • Only 1 bit different between Q and S tags: “Canonical Format Indicator” for Q-tags, “Drop Eligible Indicator” for S-tags. Current spec says CFI = 0 in inner tag. • Inner VLAN tag is only seen by TRILL knowledgeable devices. • Inner Tag priority and VLAN ID typically constructed at ingress RBridge. Suggest using S-Tag so the DEI would be available. Base Protocol Future (v2)

  8. Zero Configuration Alternative Trees • Improve scalability by decreasing the number of trees for zero configuration campuses. • Example conservative rule: • If there are one or more adjacent Rbridges with RequestTree set that are of higher order (have more IS-IS adjacencies) and none that are of a lower order, it is RECOMMENDED that an Rbridge • list one or more of such higher order Rbridges as ones it might use as a distribution tree root, • clear its RequestTree flag, and • use only such listed Rbridges as tree roots for multi-destination frames it encapsulates. Base Protocol Future (v2)

  9. Zero Configuration Alternative Trees (cont.) (x) = Order X Rbridge B (2) Rbridge A (1) Rbridge D (2) Rbridge C (4) Rbridge G (1) Rbridge E (2) Rbridge F (2) Base Protocol Future (v2)

  10. “Error” Messages • Possible reasons: • “Known” unicast arrives at destination with unknown inner DA. • Frame (other than core IS-IS) has unknown egress nickname in header. • Distribution tree root is known nickname but that RBridge does not have RequestTree bit set. • Hop Count exhausted. • Illegal field value (nickname, VLAN ID, …). • Etcetera Base Protocol Future (v2)

  11. “Error” Messages (cont.) • All/Some optional to generate? • Sent with lower priority than “erroneous” frame • What to do about “error” in lowest priority frame? • In this case, send with same priority or not at all… • How to encode/transport? • In most cases could unicast to the ingress RBridge with a special inner DA Base Protocol Future (v2)

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