SPVC Service Spanning ATM PWE 3 PSN George

Скачать презентацию SPVC Service Spanning ATM PWE 3 PSN George

9961b4f83658b088f018c0d56ddd2160.ppt

Количество слайдов: 24

Requirements • SPVC setup across ATM and PSN • Recovery No per VC / VP configuration at ATM/PSN boundary rules out simple splicing • Flexibility in where re-assembly occurs • Minimal or no change to ATM software • Simple solution needed soon RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 3

PWE Identifiers • Two Identifiers for circuit SAI - Source Attachment Identifier TAI - Target Attachment Identifier • Structure of SAI, TAI AGI - Attachment Group Identifier AII - Attachment Individual Identifier (In role of source or target AII takes on the name SAII or TAII respectively) RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 6

Mismatched Identifiers • ATM Called Party ATM Address -> Remote Switch & Interface SPVC IE -> DLCI or VPI/VCI • PWE 3 IP Address -> Remote Switch TAI -> Interface & DLCI or VPI/VCI RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 7

NSAP Format IDP AFI HO-DSP ICP 3 0 0 5 0 2 IPv 4 IDP AFI ICP HO-DSP ESI SEL RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 0 0 0 ESI SEL Port 0 0 Initial Domain Part Address Format Indicator Internet Code Point High Order Domain Specific Part End System Identifier Select 8

Mapping Identifiers (2) • SPVC IE carries DLCI or VPI / VCI • Two special AGIs are defined to indicate format of the TAII AGIfr -> AGIatm -> • No further semantics implied VPI / VCI in SPVC IE does not imply ATM RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 10

MPLS / ATM Interface • Interface between ATM and MPLS is AINI or UNI / IISP • MPLS network is modeled as a Multihomed ATM Host (with lots of addresses) • All AEs advertise the same single NSAP prefix for the MPLS Network • Prefix : : = RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 11

Re-assembly & ATM / FR IWF ATM / FR Interworking, Pseudo-wire encapsulation Re-assembly occurs at ME FRF 5, FRFpresence of AAL 5 at based onon basis of selected 8. 1 configured. Re PAE or FD bits IE and/or PME -assembly Customer Site ME 1 AE 1 Label Mapping PNNI / Q. 2931 UNI PAE 1 ATM MPLS AE 2 RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. PME 1 ME 2 12

Quality of Service (Qo. S) Qos. Reverse ATM configured at Qo. S Forward & MPLS PAE and Forward MPLS Qo. S PME Qo. S carried in ATM configured atfrom ATM inferred PME because Signaling LDP is uniditectional Signaling Customer Site ME 1 AE 1 PNNI / Q. 2931 UNI PAE 1 ATM MPLS AE 2 RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. PME 1 ME 2 13

Configuration • PMEs: AGIs and (T)AII (note AII indicates both interface and DLCI or VPI/VCI) • PAEs: NSAP and DLCI or VPI/VCI • MEs configured with special AGIs that indicate the further structure of the AII RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 14

SPVC Setup • Call is originated from the ATM side • Called Party address NSAP encoded IP loopback address for MPE + Interface encoded in ESI • SPVC IE carries DLCI or VPI / VCI RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 15

ATM Setup: PAE to ME • PAE uses normal procedures PNNI determines path to ATM address, selecting an AE Setup message formatted and sent • Call is routed through a UNI to a ME • ME terminates ATM call RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 16

ATM Setup: PAE to ME Customer Site ME 1 AE 1 PNNI / Q. 2931 UNI PAE 1 ATM MPLS AE 2 PME 1 ME 2 PAE 1 uses normal FR SPVC setup RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 17

MPLS Setup: ME to MPE • LDP session created to MPE loopback (if not already setup) • TAII created by formatting ESI + DLCI or ESI + VPI/VCI • SAII mapped based on incoming Port & VPI/VCI • Signals L 2 VPN FEC with AGI + TAII RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 18

MPLS Setup: MPE to ME Customer Site AE 1 ME 1 Customer Site Label Mapping PAE 1 ATM MPLS AE 2 PME 1 ME 2 ME 1 sends a label for FEC PME 1 responds with a label for FEC with values of SAI and TAI reversed RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 19

SPVC Setup Completion • PME uses TAII to identify interface and DLCI or VPI/VCI (could be literal or symbolic) • PME responds with reverse setup • ME then completes the ATM call RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 20

ATM Setup: ME to PAE Customer Site AE 1 PAE 1 Customer Site ME 1 Q. 2931 / PNNI ATM MPLS AE 2 PME 1 ME 2 ME 1 sends Connect message to PAE 1 RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 21

Recovery Customer Site ME 1 AE 1 Clear PTSP PAE 1 X ATM Connect Customer Site LABEL Withdraw Label Mapping Setup AE 2 ME 2 PME 1 MPLS PTSP Removes NSAP prefix for MPLS network RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 22

Conclusions • Wide deployment of PWE 3 will not happen without a tractable transition plan • Proposal places all functions within boxes in PSN (don’t expect ATM vendors to be highly motivated to assist in the transition) • So far ATM / PWE proposals from other organizations has been complex • Needs to be done by the IETF to keep it simple RST-430 2902_05_2001_c 1 © 2001, Cisco Systems, Inc. All rights reserved. 23