All Rights Reserved © Alcatel-Lucent 2006, ##### Scalability of IP/MPLS networks Lieven Levrau 30 th April, 2008 France Telecom, Cisco Systems, uawei Technologies,

All Rights Reserved © Alcatel-Lucent 2006, #####

Scalability of IP/MPLS networks

Lieven Levrau

30th April, 2008France Telecom, Cisco Systems, uawei Technologies,Telekomunikacja Polska S.A. ECI Telecom, Alcatel-Lucent

dsl20081 111 02.ppt

Benchmarking Carrier Ethernet Technologies

Workshop

Session AII.1: PW/MPLS

Krakow, Poland

All Rights Reserved © Alcatel-Lucent 20082 | Session AII.1 | April 2008

Agenda

1. MPLS control plane: Scaling the IGP to each scenario

2. MPLS transport tunnels: Scaling MPLS to each scenario


Use cases

Services to be offered by the IP/MPLS network: L2VPN P2P (VPWS)

for mobile backhauling, non-routable residential traffic

L2VPN P2MP or MP2MP (VPLS) for enterprise customers

L3VPN (IPVPN) for routable residential traffic

3 orders of magnitude for deployment scenarios: Scenario 1: 1k PE nodes Scenario 2: 10k PE nodes Scenario 3: 100k PE nodes


1 MPLS control plane:Scaling the IGP to each scenario


IGP scalability with 1k nodes

A single area is sufficient for the IGP ISIS or OSPF are eligible

Routing

ISIS or OSPF

PE P PE

ISIS or OSPF

P

ISIS or OSPF

L2 ISIS

IP/MPLS

L2 ISIS area



IP/MPLS

L2 ISIS area

IP/MPLS

L1 ISIS area

Multiple areas are required for the IGP ISIS or OSPF are eligible

Area Border Routers are required to control redistribution between areas Routes are aggregated Only Loopback addresses from one area are redistributed into other

areas

IP/MPLS

L1 ISIS area

IP/MPLS

L1 ISIS area

ABR

ABR

ABR

Routing

ISIS

PE P PEP

ISIS

L1 ISIS

P

ISISISISISIS ISIS

L2 ISIS L1 ISIS

P P P



IGP discontinuity is required: Different instances of a single IGP or different IGPs or different AS

IP/MPLS

L2 ISIS area

IP/MPLS

L1 ISIS area

IP/MPLS

L1 ISIS area

IP/MPLS

L1 ISIS area

ABR

ABR

ABR

RoutingISIS

PE P PEP

ISIS

L1 ISIS

P

ISISISISISIS ISIS

L2 ISIS L1 ISIS

P P PPE

IGP

RIP

IP/MPLS


2 MPLS transport tunnels: Scaling MPLS to each scenario


CAC and sub-100ms resiliency require MPLS traffic engineering: TE-LSPs (RSVP-TE signaled LSP) as the technology for MPLS

transport tunnels

Otherwise : LDP-LSPs (LDP signaled LSP) as the technology for MPLS

transport tunnels

For each network segment, either TE-LSP or LDP-LSP need to be chosen.

Needs for QoS and resiliency drive the choice for the LSP technology


For LDP-LSPs, a flat VPN model is sufficient (RFC 5036)

For TE-LSPs, the use of hierarchical MPLS-TE is required (RFC 4206)

For L3VPN, BGP Route Reflectors are required (RFC 4364)

Scaling up to 1k Provider Edge nodes

Routing

LSP label allocation

ISIS or OSPF

PE P PE

PW label allocation targeted LDP

ISIS or OSPF

P

ISIS or OSPF

LDP or RSVP-TE LDP or RSVP-TE LDP or RSVP-TE

L3VPN label allocation and route distribution

IP/MPLS

L2 ISIS area

RR

RR

MP-BGP



Inter-area support is required (within a single MPLS domain) : draft-ietf-mpls-ldp-interarea-03.txt Allows to setup LSPs across IGP areas without having to distribute in

the IGP each /32 PE loopback => ABRs aggregate routes to reach loopback addresses

IP/MPLS

L2 ISIS areaABR ABR

Routing (IGP)

PE PEL1 ISIS L1 ISISL2 ISISP P

LSP label allocation

PW label allocation targeted LDP

LDP

L3VPN label allocation and route distribution

10.0.0.1/32

10.0.0.1/3210.0.0/2410.0/16

Redistribution between IGP areasLabel for 10.0.0.1/32

RR

MP-BGP

RR

IP/MPLS

L1 ISIS area

IP/MPLS

L1 ISIS area



L2 ISIS areaL1 ISIS areas

ABR

ABR

ABR

PSN tunnel

PSN tunnel

PSN tunnel

MPLS service segmentation is required (multiple MPLS domains): For VPWS, multi-segment PW are required:

draft-ietf-pwe3-segmented-pw-07.txt

For multipoint L2VPN, hierarchical VPLS are required: RFC 4762

Such segmentations alleviate issues of number of LSPs in core network

L3VPN not addressed in this presentation

PW2

PW3

PW4

MS-PWT-PE

MS-PWT-PE

S-PE

S-PE

Hub-PW

Spoke-PW

Spoke-PWsVPLS

Core PE

VPLSCore PE

VPLSEdge PE

VPLSEdge PE

T-LDP

T-LDP

T-LDP

T-LDP

S-PE

Distinct IGP

Or distinct IGP instance

PW1

VPLSCore PE

Hub-PW

T-LDP

L1 ISIS areas


Thank you


Backup Material


Solutions' family for scaling MPLS

Single MPLS domain solution Flat VPN architecture: end-to-end PSN tunnels, PEs at the MPLS

edges

Multiple MPLS domain solutions Network segmentation with the intervention of border routers

(ASBRs or ABRs) in MPLS label exchange and MPLS traffic forwarding Still PSN tunnels between ultimate PEs (Flat VPN architecture), but segmented

on the infrastructure level

Service segmentation with the introduction of intermediate PEs PSN tunnels between ultimate PEs and intermediate PEs

Several solutions Each solution solves a set of issues All these solutions can coexist


Overview of IETF solutions' families

Number of PEs

Segmented routing plan

Single MPLS domain Multiple MPLS domains

Flat VPN

(end-to-end LSPs between ultimate PEs) Service segmentation

(intermediate PEs)LDP-LSPs TE-LSPsNetwork

segmentation

1k

Mono-AS, Mono-area No added feature required (distribution of IP/32 addresses into the IGP)

Full mesh of TE-LSPs possible with hierarchical TE (RFC 4206) (5) (3)

Not needed Not needed as transport LSPs are concerned

10k

Mono-AS, Multi-area LDP inter-area:draft-ietf-mpls-ldp-interarea-01.txt

can be combined with MP-BGP L2VPN (RFC4761) for flat L2VPN, wrt signaling scalability

Not feasible due to the number of LSPs, if full mesh required (1) as PSN tunnels

to be noted that LDP-LSPs as PSN tunnels can be nested into some set of smaller TE-LSPs (3)

LDP (or RSVP-TE) + BGP:RFC 3107 Carrying Label Information in BGP-4

LDP Aggregate FEC: draft-swallow-mpls-aggregate-fec-00.txt and draft-swallow-isis-detailed-reach-00.txt (4)

can be combined with MP-BGP L2VPN (RFC4761), wrt signaling scalability

MS-PW with FEC129:draft-ietf-pwe3-segmented-pw-06.txt

HVPLS RFC4762

HVPLS associating RFC4762 and 4761 PBB-HVPLS draft-balus-l2vpn-vpls-802.1ah-01.txt

VRF back-to back (for L3VPN; option a or d) and similarly Layer2peering (for L2VPN)

100k

Mono-AS, Multi-area

+ multi-instance IGP or ≠ IGPs

Multi-AS

Not feasible due to the number of LSPs (1)



As above (2) :

MS-PW; HVPLS

VRF back-to back; Layer2peering

All Rights Reserved © Alcatel-Lucent 2006, ##### Scalability of IP/MPLS networks Lieven Levrau 30 th April, 2008 France Telecom, Cisco Systems, uawei Technologies,

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