MPLS JAPAN 2004
The MPLS MetaRevolution
Kireeti Kompella

Copyright © 2004 Juniper Networks, Inc.

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1Introduction
 We are in the midst of an MPLS revolution• Network core and edge architectures are dominatedby the use and implications of MPLS
• Network services take into account MPLS
applications: VPNs, QoS/CoS, guaranteed services• “Convergence” and “Multi-Service Edge” (MSE) are
the watchwords of new network designs

 Almost every new network build-out requires
MPLS, either immediately or in the near future

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Broader Implications of MPLS
 MPLS has gone beyond a data plane paradigmof label switching and label stacks• MPLS has had a major influence on the way we thinkabout protocol design and development• MPLS underlies almost every new network service• MPLS is changing the way we think about network
provisioning and configuration• MPLS is no longer confined to the Layer 3 network“core” and “edge” -- at one end, it has penetrated theLayer 2 access network and at the other, it isimpacting the design of the new Layer 1 transport
infrastructure, in the form of Generalized MPLS

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Topics of this Presentation
 MPLS’s impact on protocol design
 MPLS’s impact on the provisioning model MPLS’s impact on Layer 2 access networks,
especially Metro-Ethernet

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1. MPLS and Protocol Design Pragmatism Extensibility
 MPLS’s suite of support protocols
 Generalized MPLS

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5Pragmatism and Protocol Design
Tenets of protocol design reinforced by MPLS:
 Reuse and extend existing protocols when they
match the requirements reasonably closely• RSVP-TE, ISIS-TE, OSPF-TE, MP-BGP• LDP and LMP are good examples of exceptions

 “Rough consensus and running code”• Many aspects of MPLS are in production deployment
long before standardization• RSVP-TE and LDP were deployed quite early• IP VPNs (RFC 2547bis), Layer 2 circuits (“martini”)
and VPLS all are revenue-generating services

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Protocol Extensibility
 Every protocol associated with MPLS isdesigned to be easily extensible• Underlying philosophy is that we do not know what
new applications will be developed! Don’t guess, butplan ahead for evolution and reuse• When MPLS was first proposed, no one visualized
the use of the MPLS paradigm in optical networks, orthe application of MPLS to Ethernet switching (VPLS)

 When designing protocol mechanisms, makethem as simple and general as possible

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The MPLS Suite of Protocols
 MPLS does not consist of a single protocol, butrather a suite of helper protocols• These include: RSVP-TE, LDP, ISIS/OSPF-TE, MPBGP, LMP, BFD …
• Each protocol has different mechanisms and modesof operation as well as target utility• For a given function, one can choose among several
protocols to get the required behavior• This improves the chances of intelligent reuse

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Generalized MPLS
 In many ways, GMPLS is a triumph of theflexibility and forward-looking nature of MPLS
• Only one new protocol was invented to enable
GMPLS, namely the Link Management Protocol, LMP• All other protocols were reused and extended• RSVP-TE, ISIS-TE, and OSPF-TE• New requirements (ASON, UNI, protection and restoration,multi-domain) have all been met with the above protocols

 The amazing thing about this is that MPLS isviewed by many as a data plane paradigm!

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2. MPLS and Provisioning Self-provisioning Auto-discovery
 Self-healing “Operational convergence”

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Self-Provisioning
 MPLS for Traffic Engineering was initially seen
as very operationally intensive• First, one had to produce a Traffic Matrix bymeasuring traffic between every pair of edge routers• Then, a full mesh had to be configured manually• This mesh of MPLS paths had to be monitored, bothfor liveness, and to verify the allocated bandwidth• Also, protection paths had to be manually configured There was no protocol help with any of this• This led to many carriers using LDP instead of RSVPCopyright © 2004 Juniper Networks, Inc.

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Self-Provisioning in Action
So muchsimpler!
PE 10
Total work
PE 9is O(N)insteadPE 8of O(N2)
PE 7

PE 11

The “old” way:at each PE, do:

PE 12
PE 1

PPPP

PE 6

PE 2

PE 4

PE 3

1. Measure b/w
to all other PEs
2. Configure an
LSP to every PE

PE 5Instead, at each PE:
3. Monitor all
A. Configure “auto-mesh”
the (N-1) LSPs
B. Configure “auto-bandwidth
C. Configure “fast reroute” (if desired)
Each PE will automatically create LSPs (with fast reroute) to allother PEs, monitor its bandwidth utilization and adjust reservatio
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Auto-Discovery
Concept firstPE 10
introducedin BGP MPLS PE 9VPNs (RFCPE 82547)

PE 11PPPE 12PP

Each PE
PE 1
is configured
PE 2 with the VPNs
it belongs toPE 3PE 7
PE 4Each PE thenPE 6PE 5“auto-discovers”
other PEs inthe same VPN
Again, an O(N2)task reduces to This same concept has been extended to Layer
VPNs, VPLS and even Layer 1 (Optical) VPNs
just O(N)

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Self-Healing with MPLS
 MPLS enables self-healing• in the control plane using Graceful Restart techniques• as well as in the data plane, using fast reroute and/or
standby paths

 Graceful Restart allows a node to gracefully
recover its control plane state after a failure Fast Reroute allows for quick recovery from alink or node failure Standby Paths serve the same function, butslower, with less state and overhead
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Operational Convergence There is much talk about “convergence” -- using
a network (or a device) for multiple services
 Equally (or more) important is convergence ofnetwork operations• Using the same concepts for multiple services

 Examples in the context of MPLS abound• GMPLS uses MPLS concepts for transport networks• Auto-discovery works identically for many VPN types• New developments (point-to-multipoint LSPs, or interdomain Traffic Engineering) reuse familiar concepts
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Self-Service Networking
 The next logical step is to off-load configuration
management to the end customer• This both eases the provider’s operational burden andoffers more flexibility to the customer

 Doing this requires strong authentication andsecurity (compare with ATM banking) Steps in this direction have been taken by theInfranet Initiative’s Client-Network Interface• Similar efforts are underway at the DSL Forum

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Infranet Client-to-Network Interface
Client requests
resources fromthe network
via the I-CNI.
The network
reconfigures
itself inresponse
I-CNI couples
Application’sneeds &Network’s delivery

I-CNI
Infranet Client-to-Network Interface

I-ICI
Infranet Inter-Carrier Interface

Application Experience
I-ICI extends ‘coupling’
across multiple providers

Network Transport

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3. MPLS and Metro Ethernet
 Metro Ethernet is a very popular, fast-growing
access technology, replacing Frame Relay/ATM
 However, Ethernet was not designed as acarrier-grade infrastructure for metro or WAN.
Ethernet’s deficiencies include:• Loops and broadcast storms are deadly• Spanning Tree doesn’t allow load balancing• Detecting link failures is slow
• Reacting to link failures is deliberately slow
• Pure Ethernet switching does not scale• No means of offering services other than switching
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Layer 2 Loops and Broadcast Storms
 If a loop occurs, packets loop for ever -- there is
not “time-to-live” in Ethernet forwarding• This is exacerbated if packets are also replicated, forexample, for broadcast traffic or flooding In many cases, the only way to recover is tophysically turn off switches• Remote administration is often not possible

 This is completely unacceptable for carrier-classnetworks• It may be acceptable for a LAN within a building
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19Layer 2 Loops and Spanning Tree
Every carrierclass network
PE 10
must have
PE 9
extra links forredundancy

PE 11

PE 12
PE 1

PPE 2

PPPPE 3

PE 8Spanning Tree PE 7
Protocol is used
to remove loops

PE 6

PE 4
PE 5

But now, these extra links
are wasted! They cannot
be used for load balancing
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However, thiswill cause adevastating
loop in an
Ethernetenvironment

If a link breaks, oneof the extra links must be
re-enabled to re-establish
connectivity -- but this isdone slowly and carefully

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Scaling and Hierarchy (or Stacking) Scaling Metro Ethernet networks is very hard
• VLANs have a limit of 4096, which is quite small• If customer MAC addresses are visible throughout theswitched network, each switch will have to holdmillions of MAC addresses• This is not scalable, secure or manageable

 Solutions to these issues include VLAN stacking
and “MAC-in-MAC”• However, these solutions are very specific to Ethernet,and do not address manageability• Also, stacking is limited to one level

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MPLS is the Right Approach Using MPLS in a Metro Ethernet network means• Ethernet switching is not used at all• Ethernet is just a transport (analogous to SDH)
• Transient loops do not bring down the network• All links can be used; load balancing is possible• Fast detection and fast recovery are possible

 Furthermore, MPLS is needed in any case tooffer customer services such as IP VPNs, VPWS
and VPLS, as well as infrastructure services likefast reroute and Traffic Engineering
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MPLS in the Future MPLS is at the perfect cusp of maturity andinnovation• Five years ago, we were arguing about protocols, andstill trying to understand where MPLS would be useful• Now, MPLS has proved itself, and is deployed in mostnetworks, and in fact carries high-revenue services• Yet, MPLS innovations have not ceased, especially inthe area of services and usability• MPLS Operations and Management (LSP ping)• Point-to-multipoint MPLS (multicast)• Virtual Private LAN Service (VPLS/MPLS LAN Emulation)

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MPLS Dreams
 MPLS+GMPLS combine to offer self-managed,
self-reconfiguring networks• Manual provisioning focuses on the service edge

 MPLS offers an effective access network• Legacy ATM-to-MPLS interworking• New metro Ethernet services

 MPLS continues to evolve and match newservice needs and expectations

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24Thank You!

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