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draft-jounay-pwe3-dynamic-pw-update-00.txt

draft-jounay-pwe3-dynamic-pw-update-00.txt. IETF 70 PWE3 Working Group Vancouver, December 2007 F. Jounay, P. Niger, France Telecom Y. Stein, RAD Data Communications H. Shah, Ciena Corp. Problem Statement. Use Case identified : Mobile Backhauling

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draft-jounay-pwe3-dynamic-pw-update-00.txt

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  1. draft-jounay-pwe3-dynamic-pw-update-00.txt IETF 70 PWE3 Working Group Vancouver, December 2007 F. Jounay, P. Niger, France Telecom Y. Stein, RAD Data Communications H. Shah, Ciena Corp

  2. Problem Statement • Use Case identified : Mobile Backhauling • CESoPSN PW used to carry the 2G traffic (mainly voice traffic) • CESoPSN specifications • Inherent trade-off between bandwidth consumption and latency => The Operator must setup CESoPSN PW so as to carefully match the PW capacity to the actual payload. • Problem Statement • when upgrading the network (e.g.: introduction of new cells, new services…) the capacity of particular PWs needs to grow without interrupting ongoing voice services used by numerous customers. • Although interface parameter update will generally be a rare event for most applications, it is still highly recommended not to negatively impact customer services. • Solutions so far proposed to increase a CESoPSN PW capacity • Teardown the existing PW, and setup a new one with the new appropriate parameters • Cons: service disruption • Setup an additional PW for the specific additional bandwidth • Cons: as many pw as updates required

  3. Possible solutions Scenario1 "New PW" • Setting up a new PW in parallel with the updated interface parameters • New FEC => new PW label • Static switching from the old to the new PW Scenario2 "PW Update" • Remaining the existing FEC • New Label Mapping message including the new interface parameters Dynamic PW Update

  4. PW Update Overview • 2 options for the solution description • Definition of a specific mechanism to allow on-the-fly updating of CESoPSN PW capacity, i.e. while avoiding service interruption • Definition of a generic mechanism for PW parameters Update • The draft defines the generic solution and addresses the CESoPSN use case • Potential other use cases • PW interface parameters of other PW Type • PW Label Update (may be required for OAM purpose, Step from static to dynamic PW (Status negotiation…) setup)… • …

  5. CESoPSN Update Solution Overview • Need a way to update the PW interface parameters without service disruption • Requirement • Signaling the update in the control plane • Synchronizing the update in the data plane (The Length field of CESoPSN PW packet is not sufficient to correctly restitute the traffic over the AC, see next slides) • Proposal • Control plane: new LDP mapping message with a PW Update sub-TLV • To be included to the LDP Label Mapping initiated to update the PW • To indicate the update behavior of the new LDP mapping • Backward compatibility: otherwise the new LDP message is usually dropped since an existing label has already been assigned to this FEC • Data plane: in-band detection based on the new label assignment • Required to allow the egress PE to forward over the AC the received traffic with the new format

  6. CESoPSN Interface ParametersExtracted from [PW TDM CTRL] • Configured by the operator • N: Number of DS0 channels in the corresponding attachment circuit that must be retrieved from the E1 frames and must be transported over the CESoPSN PW. • D: Packetization latency in millisecond (application-related) • Derived/calculated • B: Number of frames to be encapsulated per PW packet derived from the Latency B = 8*D (8 E1 frames per second) • P: Total Payload (Bytes) per PW packet P: B*N • Signaled (PW setup) • N: The interface parameter CEP/TDM Bit-Rate (0x07) is defined for all kinds of structure-aware emulation • P: The interface parameter CEP/TDM Payload Bytes (0x04) is defined for a set of TDM PW types including SAToP, CESoPSN PWs 'update' operation encompass change in configuration ensued by update signaling.

  7. LDP Label Mapping [FEC129, Label, int.par.(N, P)] PE1 PE2 ce2 ce1 N AI2 AI1 PW1 P = B (3) x N E1 frame E1 frame PW1 PW1 Payload N bytes Payload N bytes CESoPSN Interface Parameters • P = B*N N is known as it has been advertised B = P / N ?...

  8. The PW Update sub-TLV Definition of a new LDP TLV TYPE (e.g. 0x096D) 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + Generalized ID FEC + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PW Update TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Parameters | | " | | " | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0|0| Generic Label (0x0200) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|0| PW Status (0x096A) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Status Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|0| PW Update Type (0x096D)| Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Update Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • Update code • e.g., • Interface Parameters • PW label Keeping the existing LDP TLV TYPE (0x096B) For the int. parameters values

  9. Procedure (e.g. cesopsn PW update) • Increase the PW capacity • Step 1: update the PW capacity following the proposal • Step 2 : update the CE to allow it to transport more payload per E1 frames • Decrease the PW capacity • Step 1 : update the CE to allow it to transport less payload per E1 frames • Step 2: update the PW capacity following the proposal • Remark: e.g. the cesopsn PW encapsulates non used-timeslots between the step 1 and step 2.

  10. PE1 PE2 ce2 ce1 8 X AI2 AI1 PW1 L2 L2 L1 L1 PW Update Illustration for cesopsn PW • Initial config (N=15, P = D(1ms)*8*15= 120) LDP Label Mapping ([SAI1, SAI2], L1, (P=120, N=15)] LDP Label Mapping ([SAI2, SAI1], L2, (P=120, N=15)]

  11. PE1 PE2 ce2 ce1 AI2 AI1 PW1 L20 L2 L1 L10 Non Used-timeslots to be encapsulated during the transition step PW UpdateIllustration for cesopsn PW • Update config (N=20, P = D(1ms)*8*20= 160) LDP Label Mapping ([SAI1, SAI2], L10, PW Update (L, iP), (N=20, P=160)] LDP Label Mapping ([SAI2, SAI1], L20, PW Update (L, iP), (N=20, P=160)]

  12. Next Steps • Add a section describing the PW Label removal from the LFIB • Describe the MS-PW approach • Soliciting comments

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