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Composite Labels In Flexi-Grid

Composite Labels In Flexi-Grid

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Composite Labels In Flexi-Grid

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  1. Composite Labels In Flexi-Grid Adrian FarrelOld Dog Consultingadrian@olddog.co.uk

  2. Why Composite Labels? • Composite labels are a way to encode information about multiple quantities that are switched together and carry the same data flow • Examples • Waveband • TDM VCAT • OTN VCAT

  3. Do We Need Composite Labels? • Need == Want to support • Want <= Able to support • What does WP2 Say? • It is OK if this becomes a standardisation effort outside IDEALIST • Composite means? • More than one slot • Contiguous slots • Non-contiguous slots

  4. Input from ITU-T • Liaison sent to CCAMP WG • https://datatracker.ietf.org/documents/LIAISON/liaison-2014-04-23-itu-t-sg-15-ccamp-lsr-on-flexible-grid-reply-to-ietf-ccamp-ls012-attachment-1.pdf • Central frequency granularity pinned at 6.25 GHz • Slot width granularity pinned at 12.5 GHz • m <= 916 so 16 bits is adequate • No need for in-service resizing of data channels • Working assumption that “groups” of channels use the same fiber

  5. What do we need to know? • Are the slots the same type? • CS will always be 5 • Will all slots be on the same laser (Identifier value) • NO! • Could m be different for each slot? • If so, we will surely go mad • But do we need to prevent it? • Don’t constrain it • n varies per slot • Is the compound slot dynamic? • Changed through signaling • Unlikely that data plane can handle this • Note that contiguous is a special case of non-contiguous

  6. The problem is only for signalling • Routing is not an issue • Just operate as usual • Signaling has been solved before • Label format • TSpec considerations • All we have to do is pick our favourite

  7. SONET/SDH VCAT • RFC 4606 and RFC 6344 • Contains two approaches • Compound Label is simply a concatenation of multiple labels • TSpec gets a bit messy • Need to request specific slot sizes • LSP is a group of LSPs • Easier for dynamic changes • No need for composite labels • Easy for TSpec • Needs external management process • In both cases contiguity and ordering are issues

  8. OTN (G.709v3) • RFC 7139 • Just like SONET/SDH • Single LSPor • Multi-LSP • Considerably complicated by OTN over-engineering • Contiguity and ordering are still issues

  9. Data Channel Set • RFC 6002 • Fully flexible • Works for Label_Set, etc., etc. • Overly-complex for our needs? • No discussion of TSpec

  10. Waveband • RFC 3471 and RFC 3473 • Assumes contiguous lambdas • Only needs to encode top and bottom lambda

  11. Proposal (abstract form) • Require all slots of same type • CS is identical • Not all use the same laser (Identifier) • Allow different slot widths? • Allow non-contiguous slots • TSpec should say what is wanted • IGP should say what is supported • Use composite labels • Other features can be achieved using multiple LSP • ASSOCIATION object • A higher-level function

  12. Label Encoding Option1 • We only need to give CS and Identifier once per composite label • We can use different values of n and m for each slot • Maybe use a new C-Type 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Object Length (8 + 4r) | Class-Num (16)| C-Type (x) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Grid | C.S. | Identifier | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | n | m | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | n | m | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  13. Label Encoding Option2 • Repeat whole label format each time • Easier to parse • No new CNum or C-Type needed • Needs more bytes on the wire • Better future-proofing 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Object Length (4 + 8r) | Class-Num (16)| C-Type (2) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Grid | C.S. | Identifier | n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | m | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Grid | C.S. | Identifier | n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | m | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • This option was chosen in the plenary

  14. Label Set etc. • Assertion… There is no change needed to • Label Set • Acceptable Label Set • Assertion… Other objects just follow the Label object • Suggested Label • Upstream Label • Recovery Label • Label ERO subobject • Label RRO subobject

  15. TSpec • It’s complicated  • Are we asking for bandwidth or for slots? • If asking or b/w • Do we need to say that we will accept specific “chopping” • The simplest is… “I would like r slots of type {CH, m, [Identifier]}”