MPLS TE Over ATM

MPLS TE Over ATM

Advisor: Dr. Ravi Pendse

Presented by: Deepak Gulla Nishant Tambe

Outline

Goals MPLS basics with Traffic Engineering ATM basics with ATM Traffic Management Network Scenario Results / Observations Conclusions Future Work

Goals

Effects of link loading and link failure on an ATM network running MPLS Traffic Engineering (TE)

Behavior of Non-Real Time Traffic

Behavior of Real Time Traffic

MPLS with TE

MPLS with TE

IP domain IP

domain

ISP Backbone

ATM backbone ATM with

TM

MPLS Tunnel

Overview Model

Basic Network Scenario

ATM LSR

Edge LSR

LC-ATM Interfaces

hosts

hosts

LSR: Label Switch Router

LC-ATM: Label Controlled ATM

Links used : OC-3 ( 155.4 Mbps)

R5

ATM 1

R4

ATM 3

R7

ATM 2

R8

What is MPLS?

It’s a high performance method for forwarding packets through a network.

It’s a multi protocol because it can work with protocols like OSPF,RSVP,LDP, BGP etc.

It uses label (a short fixed length) with packet. All packets with same label use the same path -

a so-called label switched path (LSP). Because labels refer to paths and not endpoints, packets destined for the same endpoint can use a variety of LSP’s to get there.

Why MPLS?

Fast forwarding Traffic Engineering Virtual Private Networks It combines the scalability and flexibility

of routing with performance of layer 2.

MPLS Label Format

Layer 2 Header Layer 3 HeaderMPLS Shim Header Packet dataHeader

Label20 bits

EXP3 bits

S1bit

TTL8 bits

32 bits

Label Distribution Protocol

Request 56.2 Request 56.2

Mapping 0.40 Mapping 0.30

56.1

2 1 11 22

Intf In

Dest Intf out

Label out

2 56.2 1 0.40

Intf In

Label in

Dest Intf out

2 0.30 56.2 1

Intf In

Label In

Dest Intf out

Label out

2 0.40 56.2 1 0.30

56.3

56.2

Network 130.10.X.X / 24

3 3 3

11

1

2

22

33

MPLS Operation

Label creation and distribution LFIB table at each router Label switching path and table

lookup Forwarding of packet through the

network

MPLS Traffic Engineering

Optimizes the routing of IP traffic. Routes traffic flows across the network

based on resources the flow requires and the resources available.

Employs “Constraint-based routing” Recovers to link or node failures that

change the topology. Routing protocol used must be a link

state protocol.

ATM

ATM is a ITU-T standard for a cell relay wherein information for services is conveyed in small, fixed size cells.

ATM is a cell switching and multiplexing technology that combines the benefits of circuit switching with those of packet switching.

The cell size in ATM is 53 bytes where the payload is of 48 bytes and the 5 bytes constitutes for the header information.

It’s a connection oriented duplex communication network.

Why ATM ?

Integrated Services High speed Scalable Quality of service Well established industry standard Faster more efficient switching

ATM Cell

01234567

Generic Flow Ctrl. Virtual Path IE

Virtual Path IE Virtual Channel IE

Virtual Channel IE

Virtual Channel IE Payload Type IE

Header Error Check

Payload (48 bytes)

5 B

ytes

48 B

yte

s

CLP

Cell Header

VPI/VCI - Used to route cell to destination 24 bit information, routing significance only

CLP - Cell Loss Priority 1: discard first; 0: try not to discard

PT - Payload Type Data or OAM (Operation, Administration,

Maintenance) Congestion indication End of AAL5 packet

GFC - Generic Flow Control (UNI only) local functions

Types of ATM Connections Types of ATM Connections

•PVC (Permanent Virtual Connections)•SVC (Switched Virtual Connections)•Fundamental Connections

•Point-to-point•Point-to-multipoint

ATM CoSATM CoS •Constant Bit Rate (CBR) •Variable Bit Rate- Real time (VBRrt)•Variable Bit Rate- Nonreal time (VBRnrt)•Unspecified Bit Rate (UBR)•Available Bit Rate (ABR)

Connection setup through ATM

Connects to B

Connects to B

Connects to B

Connects to B

OK

OK

OK•Signaling request

•Connection routed – setup path

•Connection accepted /rejected

•Data flow- along same path

•Connection tear down

End system A

End system B

ATM Switching Operation

3525 45

25

Port VPI/VCI Port VPI/VCI 1 25 2 35 2 35 1 25 1 45 3 25 3 25 1 45

2

31

Input Output

•Receives cell across a link on a known VCI or VPI value

•Translation table lookup takes place to determine the

outgoing port and new VPI / VCI value is assigned.

•Retransmits cell on that outgoing link with appropriate

identifiers

Basic Network Scenario

ATM LSR

Edge LSR

LC-ATM Interfaces

hosts

hosts




R5

ATM 1

R4

ATM 3

R7

ATM 2

R8

Phase 1: MPLS TE over ATM ( NRT)

ATM LSR

Edge LSR

LC-ATM InterfacesPagent

on R6

R5

ATM 1

Pagent

on R2

R1

R4

R7

ATM 2

R8

R3

ATM 3

Pagent Path

3.2

3.1

2.2

1.2

1.1

5.1

4.2

4.1

5.2

9.2

9.1




2.1

P a t h 1

P a t h 2

P a g e n t p a t h

Path 1

Path 2

rack7r5#sh mpls forwarding-table Local Outgoing Prefix Bytes tag Outgoing Next Hop tag tag or VC or Tunnel Id switched interface 16 Pop tag 10.10.10.6/32 0 AT2/0.1 point2point 17 Pop tag 100.1.4.0/24 0 AT2/0.1 point2point 18 16 100.1.7.0/24 0 AT2/0.2 point2point 19 17 100.1.6.0/24 0 AT2/0.2 point2point 20 Pop tag 10.10.10.3/32 0 AT2/0.2 point2point 21 Untagged[T] 10.10.10.5/32 0 Tu1 point2point 22 21 10.10.10.7/32 0 AT2/0.2 point2point 23 22 10.10.10.8/32 0 AT2/0.2 point2point 24 23 10.10.10.9/32 0 AT2/0.2 point2point 25 Pop tag 100.1.3.0/24 0 AT2/0.2 point2point 26 Pop tag 100.1.5.0/24 0 AT2/0.2 point2point 27 Pop tag 100.1.9.0/24 0 AT2/0.2 point2point 28 26 10.10.10.10/32 0 AT2/0.2 point2point

Result of Phase 1Result of Phase 1

MPLS forwarding table with TE configured: MPLS forwarding table with TE configured:

rack7r5#trace 10.10.10.5

Type escape sequence to abort.

Tracing the route to 10.10.10.5

1 100.1.2.2 [MPLS: Label 27 Exp 0] 92 msec 204 msec 160 msec

2 100.1.3.2 116 msec 112 msec *

Route taken before change of Tunnels (with Route taken before change of Tunnels (with Label info): Label info):

Ping traffic showing packets drop:Ping traffic showing packets drop:

rack7r5#ping 10.10.10.5


Sending 5, 100-byte ICMP Echos to 10.10.10.5, timeout is 2 seconds:

...!!

Success rate is 40 percent (2/5), round-trip min/avg/max = 28/28/28 ms

Result of Phase 1:Result of Phase 1:

Result of Phase 1Result of Phase 1 Ping showing 100% success after change of Ping showing 100% success after change of Tunnels: Tunnels:

Route taken after change in Tunnels Route taken after change in Tunnels (with label info): (with label info):

rack7r5#ping 10.10.10.5


Sending 5, 100-byte ICMP Echos to 10.10.10.5, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 28/34/60 ms





2 100.1.4.1 20 msec 16 msec *

Phase 2: MPLS TE over ATM ( RT)Phase 2: MPLS TE over ATM ( RT)

Pagent on R6

R5

ATM 1

R4 ATM 2

R8

R3

Path 1

Path 2

ATM 3

Pagent Path

R7

T1 Link

T1 Link

Callgen R1

Callgen R2

Pagent on R2

PSQM Server

3.2

2.2

1.2

1.1

5.1

4.2

4.1

5.2

9.2

9.1

2.1

3.1

R1

GW

GW

Result of Phase 2Result of Phase 2Route taken before starting the call:Route taken before starting the call:

Route taken after change the call:Route taken after change the call:





2 100.1.3.2 64 msec 248 msec *





2 100.1.4.1 20 msec 20 msec *

Codecs (Kbps)

PSQM scores w/o MPLS TE

(just OSPF)

PSQM scores with MPLS but

no TE

PSQM scores with MPLS TE and no

ATM TM

PSQM scores with MPLS

TE and ATM TM

G.711 (64) 1.419 1.273 2.435 0.972 G.726 (32) 1.942 1.273 2.420 1.329 G.729 (8) 1.460 1.411 3.925 1.203 G.723(6.3) 1.296 1.486 2.223 1.015

Table.1: Synchronization type: 3-tone

Codecs

PSQM scores w/o MPLS TE

(just OSPF)


no TE


ATM TM


TE and ATM TM

G.711 0.669 0.670 3.240 0.627 G.726 0.683 1.104 2.486 0.648 G.729 0.709 1.242 3.541 0.674 G.723 0.742 0.921 2.847 0.691

Table 2: Synchronization type: (DTMF)

Codecs PSQM scores w/o MPLS TE

(just OSPF)


no TE


ATM TM


TE and ATM TM

G.711 2.012 2.145 4.129 1.746 G.726 2.421 2.104 5.031 2.124 G.729 2.742 2.546 5.112 1.842 G.723 2.396 2.286 4.912 1.910

Table 3: Synchronization type: no-sync

Results of Phase 2:

• During congestion MPLS automatically switches the path to the other path that is under utilized.

• LS1010 is not working as LSR when configured along with the 3600 series routers with the existing IOS, hence we cannot use SVC’s.

• The success rate of the call increased by increasing the PCR value of the switch.

• Due to the configuration done codecs G.729 and G.723 also yielded better results when compared to other codecs inspite of their lower bit rate

Observations

Goals

Effects of link loading and link failure on an ATM network running MPLS Traffic Engineering (TE)

Behavior of Non-Real Time Traffic

Behavior of Real Time Traffic

Conclusions

• The PSQM scores obtained were better for all scenarios by configuring MPLS TE with ATM TM.• Recovery of links is faster when MPLS TE with ATM TM is used.• G.723 inspite of lower bit rate yielded comparably equivalent scores hence for our scenario we would recommend using it.

Future Work

• MPLS QoS can be implemented on the existing scenario by replacing 3600 series with 7200 series routers.• ATM QoS can be implemented by replacing LS1010’s with that of MGX 8500 series switches. • Implement VPN extending our existing network scenario.• Behavior of real time traffic with more number of calls.

•Measure parameters such as jitter, echo, delay etc.

References

• MPLS Technology and Applications – Bruce David & Yakov Rekhter

• Cisco ATM Solutions – Cisco Press

• www.Cisco.com

• RFC 3031

• www.mplsrc.com

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MPLS TE Over ATM

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