SDN in IP/MPLS NetworksMochammad Irzanm.irzan@gmail.comirzan@juniper.net

Agenda

● IP/MPLS in the Service provider Network● Planning tool● SDN in IP/MPLS a.k.a PCE● Use cases

IP Network

● Packet forwarding based on packet's header and routing table

● Distributed control plane– Routing protocol : OSPF, ISIS, BGP, RIP

– Hop-by-hop routing information propagation

– Distributed calculation

● Best path based on metric

IP Network

R1 R2 R3 R4

R5 R6

A B

IP Network (...)

R1 R2 R3 R4

R5 R6

A B

Routing protocol

IP Network (...)

R1 R2 R3 R4

R5 R6

A B

Routing protocol

IP Network (...)

R1 R2 R3 R4

R5 R6

A B

Routing protocol

Prefix Outgoing Intf Metric

B 2 3

… … ….

IP Network (...)

● Packet forwarding follow the best path● Explicit routing/Traffic Engineering is

complicated/difficult– Policy based routing

– Metric manipulation

IP Network (...)

R1 R2 R3 R4

R5 R6

A B

IP Network (...)

R1 R2 R3 R4

R5 R6

A B

IP/MPLS Network

● Packet forwarding is based on label information● Used the existing IP routing infrastructure● Label distribution protocol

– MP-BGP, LDP, RSVP

● Traffic Engineering/Explicit routing is easier● Multiservice network

IP/MPLS Network

R1 R2 R3 R4

R5 R6

A B

LER LERLSR

IP/MPLS Network (...)

● LER (Label Edge Router)– Push/Pop Label

● LSR (Label Switch Router)– Label Swapping

MPLS label

MPLS label (20 bit) Exp. Bit (3 bit) Stack bit (1 bit) TTL (8 bit)

L2 Header MPLS Label L3 Header Payload

L2 Header Label 1 Label 2 L3 Header Payload

L2 Header Label 1 ... Label N L3 Header Payload

Label Distribution Protocol

● LDP– Follow IP Routing protocol

● RSVP– Explicit path/Traffic Engineering

● MP-BGP– L3VPN, L2VPN, VPLS, EVPN

IP/MPLS Network (...)

R1 R2 R3 R4

R5 R6

A B

LER LERLSR

prefix Label in Label out Out. intf. Metric

B Null 100 2 3

... ... …. ... ...

Routing Table

IP/MPLS Network (...)

R1 R2 R3 R4

R5 R6

A B

LER LERLSR

Label in Label out Out. Intf.

100 120 2

... ... ...

Label Table

IP/MPLS Network (...)

R1 R2 R3 R4

R5 R6

A B

LER LERLSR

Label in Label out Out. Intf.

120 100 2

... ... ...

Label Table

IP/MPLS Network (...)

R1 R2 R3 R4

R5 R6

A B

LER LERLSR

prefix Label in Label out Out. intf. Metric

B 100 null 2 3

... ... ... ... ...

Routing Table

Explicit Routing/Traffic Engineering

R1 R2 R3 R4

R5 R6

A B

LER LERLSR

prefix Label in Label out Out. intf. Metric

B null 100 LSP1 3

... ... ... ...

Routing Table

MPLS Use Case 1, IP routing

R2 R3 R4/LER

R5 R6

A B

R1/LER

LSReBGP eBGP

iBGP

MPLS Use Case 1 (...)

R2 R3 R4/LER

R5 R6

A B

R1/LER

LSReBGP eBGP

iBGP

Prefix Next-hop metric

B1 X1 1

B2 X2 1

… 1

Bn Xn 1

MPLS Use Case 1 (...)

R2 R3 R4/LER

R5 R6

A B

R1/LER

LSReBGP eBGP

iBGP

Prefix Next-hop metric Label

B1 R4 1 100

B2 R4 1 100

… ... ... ...

Bn R4 1 100

MPLS Use Case 1 (...)

R2 R3 R4/LER

R5 R6

A B

R1/LER

LSReBGP eBGP

iBGP

Prefix Label in Label out Out. Intf.

R4 100 120 2

… ... ... ...

MPLS Use Case 1 (...)

R2 R3 R4/LER

R5 R6

A B

R1/LER

LSReBGP eBGP

iBGPPrefix Label in Label out Out. Intf.

R4 120 110 2

… ... ... ...

MPLS Use Case 1 (...)

R2 R3 R4/LER

R5 R6

A B

R1/LER

LSReBGP eBGP

iBGPPrefix Label in Label out Out. Intf.

R4 110 null 2

… ... ... ...

MPLS Use Case 1 (...)

R2 R3 R4/LER

R5 R6

A B

R1/LER

LSReBGP eBGP

iBGPPrefix Label in Label out Out. Intf.

R4 110 null 2

… ... ... ...

Prefix Next-hop metric

B1 X1 1

B2 X2 1

… 1

Bn Xn 1

MPLS Use Case 2, VPN services

R2 R3 R4/LER

R5 R6

A1 B1R1/LER

LSR

eBGP OSPF

MP-BGP

B2A2

MPLS Use Case 2 (...)

● Two Label– Label 1 : VPN label

– Label 2 : Egress LER

● Label 1 is used at the egress LER● Label 2 is used for label swapping in the

IP/MPLS core (LSR)

MPLS Use Case 3

R1

R2

R3 R4

R6

R7

5G

5G 5G

3G5G

2G

2G

MPLS Use Case 3 (...)

R1

R2

R3 R4

R6

R7

5G

5G 5G

3G5G

2G

2G

LSP R1-R6 : 2G

MPLS Use Case 3 (...)

R1

R2

R3 R4

R6

R7

5G

5G 5G

3G5G

2G

2G

LSP R1-R6 : 2GLSP R2-R6 : 3G

MPLS Use Case 3 (...)

● The LSP tunnel configuration is distributed and independent

● Result might be different on different time● Can be resolved using LSP priority and

preemption● Can be complex to deploy

MPLS Use case 4R1

R2

R3

R4

R6

R7

R5

R8

MPLS Use case 4 (...)R1

R2

R3

R4

R6

R7

R5

R8

S1

S2

S3 S5

S7

S6

MPLS Use case 4 (...)

● Packet and optical network are not fully overlapping

● Multiple L3 link may overlap on the optical transmission

● L3 link R3-R5 and R4-R7 share the same optical transmission S3-S7

Planning tool

● Centralized optimization engine ● What-if scenario ● Identify potential bottleneck● Planning and design● Off-line tool

Path Computation Element

PCC

PCE

PCC

PCC

PCEP PCEP

PCEPRFC5440

Path Computation Element

Topology DiscoveryPath calculationPath InstallationBGP-LS

OSPFISISetc

PCEPNetconf/

Yang

Use case 1, Path Diversity

LSP1

LSP2

Use case 2, TE++

R1

R2

R3 R4

R6

R7

5G

5G 5G

3G5G

2G

2G

LSP R1-R6 : 2GLSP R2-R6 : 3GDynamic LSP create/tear down based on traffic load

Use case 3, Bandwidth Calendaring

Use Case 4, Programmable path cost function

● Home grown CSPF algorithm● IGP Metric tuning● Controlling exit point

Use Case 5, Packet Optical Integration

R1

R2

R3

R4

R6

R7

R5

R8

S1

S2

S3 S5

S7

S6

PCE

Thank You