High Availability In
MPLS/GMPLS Networks

Presentation Title: MPLS Japan
Rev/date: 10/30/02

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MPLS/GMPLS Network
Relationships
MPLS(packet based)(Metro Ethernet)
Out of band control plane

GMPLS(TDM/optical)
SONET/SDH

Optical(lambdas/fiber)

Presentation Title: MPLS Japan
Rev/date: 10/30/02

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High Availability Requirements•••

50 ms switchover time
– Current standards for Telecom networks
Failure “hierarchy”– Layer 1 and 2 faster restoration than layer 3– Transparency– Depends on facilities and topology
Current capabilities– SONET/SDH APS < 50 ms– Link bundling< 45 ms– MPLS fast re-route< 45 ms– MPLS LER re-signaling< 7s– IP re-routing< 7sTarget Five 9’s Of Voice Network
Presentation Title: MPLS Japan
Rev/date: 10/30/02

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Implementation Options•••

Internal capabilities– Hardware/software redundancy– Architecture distribution
Control plane resiliency– Routing stability – e.g. graceful re-start– Signaling flexibility
Network resiliency– Protection and restoration schemes• 1:1 APS like
• n:1 n>=1 – traffic engineering implications• Re-signaling– Control plane interaction• Secondary LSP pre-computed• Secondary LSP pre-computed and signaled• Fast reroute – multiple points of repair– Fault detection at Layer 1 or 2, routing (IGP), orsignaling (RSVP-TE)
Presentation Title: MPLS Japan
Rev/date: 10/30/02

4Today’sFocus

Fast Reroute Challenges•

Re-route from ingress (required for CR-LDP)
E
LER

A

X

F
B

GC

D

LSR

Protected LSP– Detect failure, notify ingress, re-calculate, signal new LSP– Difficult to meet 50ms requirements•Pre-compute backup LSPs
ELER

A

X

FX

B

GCX

D
Protected LSP

LSR– How many scenarios to calculate ?
– Consumes enormous resources (network and state)

Requires Flexible Local Repair Mechanisms
Presentation Title: MPLS Japan
Rev/date: 10/30/02

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GMPLS and MPLS Status••GMPLS– Optical applications generally end-to-end– Functional specification stage– ITU, OIF and IETF CCAMP standards bodies– Mapping to ASON/ASTN models– Out-of-band control plane increases complexity– Consensus emerging on use of GMPLS notify object
MPLS– Packet mechanisms have flexibility (IP, metro Ethernet)– IETF MPLS working group driven– Original ideas from Cisco, Juniper and Avici– Consolidated fast reroute draft• Draft-ietf-mpls-rsvp-fastreroute-00.txt

Presentation Title: MPLS Japan
Rev/date: 10/30/02

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Fast Reroute Concepts
Backup LSP Tunnel

X

LER

Point of Local
Repair (PLR)••

X

Merge Point(MP)Protected LSP

Next Hop (link)protection

Next Next Hop(link and node)
protection

1:1 backup – detour LSPs
N:1 backup – bypass tunnels (facility backup)

Traffic Engineering and RSVP-TE
Presentation Title: MPLS Japan
Rev/date: 10/30/02

7LSRDetour LSPs
ELER•••

AX

FGCX

B

D

1:1 backup at any point on protected LSP– Up to n-1 backups
Preserves explicit route characteristics– Network resources must be reserved– State information must be saved
Switchover time can be immediate on failure detection– Holdover priorities optional

Presentation Title: MPLS Japan
Rev/date: 10/30/02

8LSR

Bypass LSPs
Place label CD
In bypass LSP
HLER

EA

FXB

CLabel AB•••Multiple LSPs can be backed up– Traffic constraints overbooked
Protected LSP label management– PLR needs to learn MP label– Platform wide labels strongly suggested
Switchover constraints same as for detour

Presentation Title: MPLS Japan
Rev/date: 10/30/02

9JGDLabel CDLSR

Detour Path Calculation
EA

LER

A B C D LSR
CSPF generates ERO
RSVP-TE signals path
1 Mbps

•FB

GC

D

E F C
1 Mbps F G D
Detour object identifies
Detour object identifies‘A’ as PLR
CSPF calculates ‘C’ as MP ‘B’ as PLR
CSPF calculates ‘D’ as MP
RSVP-TE signals path
RSVP-TE signals path
1 MbpsCSPF can support disjoint paths– Enables support for Shared Risk Link Groups (SLRGs)• Requires knowledge of lower layer transport•LSR

New PATH message objects– Fast reroute – identifies protected LSPs andattributes – priority, hold time etc.
– Detour object identifies PLR and any restrictions

Presentation Title: MPLS Japan
Rev/date: 10/30/02

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Bypass Path Calculation
1 MbpsA B C D J

HLER

EA

A B C D LSR
CSPF generates ERO
RSVP-TE signals path
1 Mbps•FBC
BC CD DLSRJGDCD DLSRE F GD
Detour object identifies‘A’ as PLR
CSPF calculates ‘D’ as MP
RSVP-TE signals path

LSRDLSR

1 MbpsRROFacility backup identified in Fast reroute object– However, generally manually provisioned••••

One LSP selected as control for merged LSPs
All messages (path, resv) directed over bypass tunnel
Supports bandwidth over-subscription (with limits)
Record Route Object to correlate labels– A learns CD is label between C and D (MP)Presentation Title: MPLS Japan
Rev/date: 10/30/02

11Path Restoration••

After local repair, LSP routing may be sub-optimal
After failure detected– Error message/code returned to ingress– IGP routing update will occur– Order of seconds to update•

Re-computation of TE tunnel(s)– Policy determines long term repair and optimization
scenario– Hold over on backup for primary path recovery

Time Sensitivity Removed
Presentation Title: MPLS Japan
Rev/date: 10/30/02

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Summary•••

Protection and restoration key issues for MPLS/GMPLS
acceptance– GMPLS and optical requirements evolving– MPLS fast reroute understood and implemented
Two main fast reroute mechanisms– Detour LSPs – single LSP protection– Bypass tunnels – supports multiple LSPs
– Mechanisms can be be co-resident
MPLS/GMPLS driving towards carrier-classcharacteristics– Five 9’s operation or better becoming a reality

Application At All Network Layers
Presentation Title: MPLS Japan
Rev/date: 10/30/02

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Thank You
Q&AJohn Fryer
Vice President of Marketing
email: jfryer@netplane.com
url: www.netplane.com
Presentation Title: MPLS Japan
Rev/date: 10/30/02

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