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SPVC Service Spanning ATM & PWE3/PSN George Swallow [email protected]. The problem. Customer Site. Customer Site. Customer Site. Customer Site. PE. MPLS. ATM. Customer Site. Customer Site. Requirements. SPVC setup across ATM and PSN Recovery - PowerPoint PPT Presentation
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1RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
SPVC ServiceSpanning ATM & PWE3/PSN
George [email protected]
2RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
The problem
MPLS
PE
Customer Site
ATM
Customer Site
Customer Site
Customer Site
Customer Site
Customer Site
3RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
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
4RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
Terminology
MPLS
Customer Site
Customer Site
ATM
AE2 ME2
AE1 ME1
PME1PAE1
P - ProviderA - ATMM - MPLSE - Edge
Key:
5RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
Solution Elements / Issues
• MPLS / ATM Interface
• Addressing
• Circuit Identification
• Recovery
6RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
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)
7RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
Mismatched Identifiers
• ATM
Called Party ATM Address -> Remote Switch & Interface
SPVC IE -> DLCI or VPI/VCI
• PWE3
IP Address -> Remote Switch
TAI -> Interface & DLCI or VPI/VCI
8RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
NSAP Format
Port35
00
02 IPv4 0
000
00
00
00
00
00
AFI ICPIDP
HO-DSP ESI SEL
IDP Initial Domain Part
AFI Address Format Indicator
ICP Internet Code Point
HO-DSP High Order Domain Specific Part
ESI End System Identifier
SEL Select
9RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
Mapping Identifiers
IDP HO-DSP ESISEL
DLCI
Called Party Address
FEC TAII
SPVC
Target for LDP
IP Address ESI DLCI
10RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
Mapping Identifiers (2)
• SPVC IE carries DLCI or VPI / VCI
• Two special AGIs are defined to indicate format of the TAII
AGIfr -> <ESI><DLCI>
AGIatm -> <ESI><VPI><VCI>
• No further semantics implied
VPI / VCI in SPVC IE does not imply ATM
11RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
MPLS / ATM Interface
• Interface between ATM and MPLS is AINI or UNI / IISP
• MPLS network is modeled as a Multi-homed ATM Host (with lots of addresses)
• All AEs advertise the same single NSAP prefix for the MPLS Network
• Prefix ::= <IDP for IPv4><IP Net Prefix>
12RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
Re-assembly & ATM / FR IWF
MPLS
Customer Site
Customer Site
ATM
AE2 ME2
AE1 ME1
PME1PAE1
UNI
ATM / FR Interworking, FRF5, FRF 8.1 configured
at PAE and/or PME
PNNI / Q.2931
Pseudo-wire encapsulation selected on basis of
Re-assembly
Re-assembly occurs at ME based on presence of AAL5
IE or FD bits
Label Mapping
13RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
Quality of Service (QoS)
MPLS
Customer Site
Customer Site
ATM
AE2 ME2
AE1 ME1
PME1PAE1
UNI
PNNI / Q.2931
Qos configured at PAE and PME
Forward MPLS QoS inferred from ATM
Signaling
Reverse MPLS QoS configured at PME because
LDP is uniditectional
Forward & Reverse ATM QoS carried in ATM
Signaling
14RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
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
15RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
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
16RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
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
17RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
ATM Setup: PAE to ME
MPLS
Customer Site
Customer Site
ATM
AE2 ME2
AE1 ME1
PME1PAE1
UNI
PAE1 uses normal FR SPVC setup
PNNI / Q.2931
18RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
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 L2VPN FEC with AGI + TAII
19RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
MPLS Setup: MPE to ME
MPLS
Customer Site
Customer Site
ATM
AE2 ME2
AE1 ME1
PME1PAE1
ME1 sends a label for FEC <SAI><TAI>
Label Mapping
Label Mapping
PME1 responds with a label for FEC with values of SAI and TAI reversed
20RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
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
21RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
ATM Setup: ME to PAE
MPLS
Customer Site
Customer Site
ATM
AE2 ME2
AE1 ME1
PME1PAE1
ME1 sends Connect message to PAE1
Q.2931 / PNNI
22RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
Recovery
MPLS
Customer Site
Customer Site
ATM
AE2 ME2
AE1 ME1
PME1PAE1
PTSP Removes NSAP prefix for MPLS network
X LABEL Withdraw
Label Mapping
Clear
Connect
Setup
PTSP
23RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
Conclusions
• Wide deployment of PWE3 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
24RST-4302902_05_2001_c1 © 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.© 2001, Cisco Systems, Inc. All rights reserved.
Thank You
