Network Convergence:
From Virtual Circuits to Pseudo-Wires.

Luca Martini, Technical Leader , Cisco Systems© 2004, Cisco Systems, Inc. All rights reserved.

1

Agenda●“Martini draft” Background and History.

●

Network design principle.

●

Network management design.

●

Organization design.

© 2004, Cisco Systems, Inc. All rights reserved.

2

History:●

Year 1998/99:
ATM has failed to deliver the multi-service networks, and is
too slow/expensive●

Huge bandwidth demand. ( or at least we thought so )●●New network from the ground up:
All packet based services must run on one single packetnetwork.

●

MPLS is an emerging technology with the best
management/granularity compromise●Must create new telecom market competition to make network
elements and services a commodity.

●© 2004, Cisco Systems, Inc. All rights reserved.

3Motivation of "draft-martini"●

Next Generation SP design:
Classical frame/ATM is expensive and does not integrate well.

●

Multi-service Backbone.

●

Re-deployment or expand existing Hardware.

●●Multiple vendor Implementation = market competition.

●

New lower cost services with market acceptance.

© 2004, Cisco Systems, Inc. All rights reserved.

4

Protocol Design Criteria●"Simple" protocol Implementation.

●

Must use existing hardware when possible.

●

Leverage MPLS, for multi-service Core network●

Support existing SP protocols, and existing CPE●

Similar operational model to standard SPservices.

© 2004, Cisco Systems, Inc. All rights reserved.

5

Result:●

11 vendors inter-operated when I stopped counting.

●Draft-martini is LDP based, a modern design.

●

●

●

Point-to-point links - operationally similar to classicalframe/atm.
MPLS based Multi-service network.
Service management granularity/scalabilitycompromise© 2004, Cisco Systems, Inc. All rights reserved.

6

Scaling MPLS to the Edge
●Must take advantage of MPLS "stackingarchitecture" on all levels:●●●

Routing information ( RSVP, LDP/IGP )FIB: customer specific information need not be in the core ofthe network
Hierarchical management.
MPLS
Edge
RouterMPBGP/Targeted LDP

1 million routes Distributed

RSVP-TE
2500 tunnels

Bigger label stack
OSPF/LDP
10000 routes

MPLS
Core
RouterMore info/element
Fault detection dependency© 2004, Cisco Systems, Inc. All rights reserved.

7

IP VS PW
Success
PW successsuccess isis due
due toto networknetwork
Success ofof IP
IP isis due
due toto scalingscaling ●● PW
convergenceproperties
convergence potential
potential
properties●●Notion
No aggregation
aggregation isis possible.
possible.
Notion ofof longest
longest prefix
prefix match
match -- ●● No●●The>> aggregation
The network
network Egress
Egress point
point ofof aa
aggregation ofof information.
information.
PW
●●The
PW is
is static
static ,, andand always
always known,known,
The network
network Egress
Egress point
point ofof ananwhenIP
when thethe packet
packet entersenters thetheIP packet
packet isis notnot known
known atatnetwork.
ingress
network.
ingress toto thethe network.
network.
●●Management
PW management:
management: Each
Each PW
PW ororManagement ofof IP
IP isis performed
performed ●● PW
Networkon
Network only
only ??
on aa network
network link
link byby link
link basis
basis
●●
SP
●●
NoSP manages
manages each
each PW.
PW.
No SP
SP endend useruser toto endend useruser●●“Stacking”
management.
“Stacking” insuresinsures thatthat aa single
singlemanagement.
user●●Address
user does
does notnot require
require specificspecific
Address Aggregation
Aggregation insuresinsures
information
thatinformation inin thethe core
core network.
network.
that aa single
single useruser does
does notnot
requirerequire specificspecific information
information ininthethe core
core network.
network.
●●© 2004, Cisco Systems, Inc. All rights reserved.

8

Learn the IP lesson
We must learn and use the architectural advantages ofIP.
● Network state/information needs to be bounded.
● Aggregation of network information.
● SP monitoring of aggregate information only.
●MPLSEdge
RouterBigger label stack
MPLSCoreRouterMore info/element
Fault detection dependency© 2004, Cisco Systems, Inc. All rights reserved.

9

Stacking of Management layer.
●

Replicating a legacy network management will notscale !
●●Example: ATM OAM Loop cells.

The MPLS network needs to be trusted to perform asspecified.
●

Monitoring each PW is not necessary, nor practical.

PE monitoring should be sufficient to detect 99% of thefailures.

●●Core network status is propagated by IGP protocols.

●

Monitor individual network link using BFD© 2004, Cisco Systems, Inc. All rights reserved.

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Hierarchical Network FaultManagement.
●

Monitor Core Links ( BFD )IGP notification of link failure.

●●

Repair: MPLS Fast-reroute/IGP fast convergence.

●

Total failure ?
Reachability information is withdrawn●PE is notified of failure immediately.
●●

Customer link fault notification.
PE
2CE
3PE
4

LAN

WAN(core)

CE
2CE
1

Customer Prem.

PE
1

SP LAN (BFD)© 2004, Cisco Systems, Inc. All rights reserved.

P
1
MPLS CoreX

PE
3

CE
5CE
4

Customer Premise
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The weak link.
●The network's weak link : the Human.

●Example: Bypass LSP for Fast-rerouteManual Static network configuration routing:●Is expensive.

●Is very prone to errors.

●

Automatic routing ( bypass LSP/RSVP-TE etc.)●

Is not as easy to understand.

●

System can have Bugs. ( but bugs eventually get fixed)●© 2004, Cisco Systems, Inc. All rights reserved.

12

New Organization Interactions.
●

●

●

●

Converged networks -> cost savings -> convergedorganization.
Biggest hurdle to deployment of a multi service
converged network.
design/support organization structure must match
new converged network design.
IP/Frame/ATM network delineation is now blurred
They all share the same core network.

●All existing organizations need to be re-trained.

●© 2004, Cisco Systems, Inc. All rights reserved.

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Organization design●

Engineering <> operational support groups:
Operations groups “own” the network.

●

Engineering design groups “design” the new network.

●

●

●

●

●

No "tossing over the wall" !
For a successful converged network
responsibility must be shared.
Unfortunately more often then not, Network
boundaries reflect internal organization boundaries.
Support, and engineering organizations must bemerged at least at head of department level.
© 2004, Cisco Systems, Inc. All rights reserved.

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Conclusions●A protocol designed for the market.

●Learn IP network architecture lesson.

●"Divide and conquer" strategy.

●

Design the network properly, and trust it!

© 2004, Cisco Systems, Inc. All rights reserved.

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Ethernet OAM Standards Status© 2003, 2004, Cisco Systems, Inc. All rights reserved.
© 2004, Cisco Systems, Inc. All rights reserved.

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