1. MPLS
MultiProtocol Label Switching

2. Overview Drawbacks of Traditional IP Routing Basic MPLS Concepts
MPLS Labels
Traffic Engineering with MPLS
MPLS Architecture
Lesson Aim
<Enter lesson aim here.>

3. Drawbacks of Traditional IP Forwarding
Routing protocols are used to distribute Layer 3 routing information.
Forwarding is based on the destination address only.
Routing lookups are performed on every hop.

4. Drawbacks of Traditional IP Forwarding (Cont
Drawbacks of Traditional IP Forwarding (Cont.) Traditional IP Forwarding
Every router may need full Internet routing information (more than 100,000 routes).

5. Drawbacks of Traditional IP Forwarding (Cont
Drawbacks of Traditional IP Forwarding (Cont.) Traditional IP Forwarding
Every router may need full Internet routing information (more than 100,000 routes).
Destination-based routing lookup is needed on every hop.

6. Drawbacks of Traditional IP Forwarding (Cont.) IP over ATM
Layer 2 devices have no knowledge of Layer 3 routing information—virtual circuits must be manually established.

7. Drawbacks of Traditional IP Forwarding (Cont.) IP over ATM
Layer 2 devices have no knowledge of Layer 3 routing information—virtual circuits must be manually established.
Layer 2 topology may be different from Layer 3 topology, resulting in suboptimal paths and link use.
Even if the two topologies overlap, the hub-and-spoke topology is usually used because of easier management.

8. Drawbacks of Traditional IP Forwarding (Cont.) Traffic Engineering
Most traffic goes between large sites A and B, and uses only the primary link.
Destination-based routing does not provide any mechanism for load balancing across unequal paths.

9. Basic MPLS Concepts
MPLS is a new forwarding mechanism in which packets are forwarded based on labels.
Labels usually correspond to IP destination networks (equal to traditional IP forwarding).
Labels can also correspond to other parameters, such as QoS or source address.
MPLS was designed to support forwarding of other protocols as well.

10. Basic MPLS Concepts (Cont.) Example

11. Basic MPLS Concepts (Cont.) Example
Only edge routers must perform a routing lookup.

12. Basic MPLS Concepts (Cont.) Example
Only edge routers must perform a routing lookup.
Core routers switch packets based on simple label lookups and swap labels.

13. Traffic Engineering with MPLS
Traffic can be forwarded based on other parameters (QoS, source, ...).
Load sharing across unequal paths can be achieved.

14. SHIM Layer N D P 3 2 1
MPLS

15. MPLS Labels
MPLS technology is intended to be used anywhere regardless of Layer 1 media and Layer 2 protocol.
MPLS uses a 32-bit label field that is inserted between Layer 2 and Layer 3 headers

17. MPLS Labels (Cont.) Label Format
MPLS uses a 32-bit label field that contains the following information:
20-bit label
3-bit experimental field
1-bit bottom-of-stack indicator
8-bit TTL field

18. MPLS Label Stack
Protocol identifier in a Layer 2 header specifies that the payload starts with a label (labels) and is followed by an IP header.
Bottom-of-stack bit indicates whether the next header is another label or a Layer 3 header.
If s=0, then label stack implementation is in use.
If s=1, then last label
Receiving router uses the top label only.

19. MPLS Label Stack (Cont.)
Usually only one label is assigned to a packet.
The following scenarios may produce more than one label:
MPLS VPNs (two labels: The top label points to the egress router and the second label identifies the VPN.)
MPLS TE (two or more labels: The top label points to the endpoint of the traffic engineering tunnel and the second label points to the destination.)
MPLS VPNs combined with MPLS TE (three or more labels.)

20. MPLS Labels (Cont.)

21. MPLS Labels (Cont.)

22. Some MPLS Terms... FEC - Forward Equivalence Class
LER - Label Edge Router
LSR - Label Switch Router
Label – 20 bit value
Label Stack - Multiple labels containing information on how a packet is forwarded.
Label Switch Path - path that a packet follows for a specific FEC
LDP - Label Distribution Protocol, used to distribute Label information between MPLS-aware network devices

23. FEC
A packet can be mapped to a particular FEC based on the following criteria:
Destination IP address
- Source IP address
TCP/UDP port
- Class of service,
- Application used etc…
Any combination of the previous criteria.

24. Label Switch Routers
LSR primarily forwards labeled packets (label swapping).
Edge LSR primarily labels IP packets and forwards them into the MPLS domain, or removes labels and forwards IP packets out of the MPLS domain.

25. Label Switch Routers (Cont.) Architecture of LSRs
LSRs, regardless of the type, perform these functions:
Exchange routing information
Exchange labels
Forward packets
The first two functions are part of the control plane.
The last function is part of the data plane.

26. Label Switch Routers (Cont.) Architecture of LSRs (Cont.)

27. Label Switch Routers (Cont.) Architecture of Edge LSRs

28. LSP Label-Switched Path Simplex L2 tunnel across a network
New Delhi
Mumbai
LSP
Label-Switched Path
Simplex L2 tunnel across a network
Concatenation of one or more label switched hops
Analogous to an ATM PVC

29. LSR MPLS enabled router is called label Switching Router
New Delhi
Mumbai
LSP
LSR
MPLS enabled router is called label Switching Router
Forwards MPLS packets using label-switching
Executes one or more IP routing protocols
Participates in MPLS control protocols

30. MPLS Terminology Ingress LSR (“head-end LSR”) Transit LSR
Egress
LSR
Ingress
LSR
New York
Transit
LSR
San
Francisco
Transit
LSR
LSP
Ingress LSR (“head-end LSR”)
Examines inbound IP packets and assigns them to an FEC
Generates MPLS header and assigns initial label
Transit LSR
Forwards MPLS packets using label swapping
Egress LSR (“tail-end LSR”)
Removes the MPLS header

31. MPLS Label Assignment/Binding
Assign label
Label assigned
Data
Control
Upstream Node
Downstream Node

32. MPLS Label Assignment/Binding
Label Request for FEC
Upstream
LDP peer
Net:
Label: 17
Advertise
incoming
label
Net:
Label: 52
(3, 29)
Net:
Label: 29
MPLS Table In
Out
Downstream
LDP peer
LSR 3 1 4 5 2 3
MPLS Table In
Out
(1, 17)
MPLS Table In
Out
(5, 52)
Receive
outgoing
label
(3, 35)
(4, 17)
(2, 52)

33. Label Operations
PUSH
SWAP
POP

34. Routing Information Base Forwarding Information Base
Label Pushing S0 S1 N D P 3 2 1
Routing Information Base
Receive Logic
Transmit Logic
Input port
Output port
Forwarding Information Base
MPLS
Ingress Node D H4 H3 D H4 H3 D H4 H3 S D H4 H3 H2 T2 S D H4 H3 H2 T2
101 00 10 01 11 S
101 00 10 01 11

35. Routing Information Base Forwarding Information Base
Label Swapping S0 S1 N D P 3 2 1
Routing Information Base
Receive Logic
Transmit Logic
Input port
Output port
Forwarding Information Base
MPLS
Transit Node D H4 H3 S D H4 H3 S D H4 H3 H2 T2 S D H4 H3 H2 T2 S
101 00 10 01 11 S
101 00 10 01 11 S

36. Routing Information Base Forwarding Information Base
Label Popping S0 S1 N D P 3 2 1
Routing Information Base
Receive Logic
Transmit Logic
Input port
Output port
Forwarding Information Base
MPLS
Egress Node D H4 H3 D H4 H3 D H4 H3 H2 T2 D H4 H3 S D H4 H3 H2 T2 S
101 00 10 01 11
101 00 10 01 11 S

37. Label databases FIB - Forwarding Information Base
LIB – Label Information Base
LFIB - Label Forwarding Information Base

38. LSR Operation Each LSR maintains a connection table Connection Table
(port, label)
Out
(1, 22)
(1, 24)
(1, 25)
(2, 23)
(2, 17)
(3, 17)
(4, 19)
(3, 12)
Label
Operation
Swap
Port 1
Port 3
Port 2
Port 4 25 IP 19 IP

39. MPLS Forwarding Example1 2
Ingress Routing Table
Destination
Next Hop
134.5/16
/24
(2, 84)
(3, 99)
MPLS Table In
Out
(6, 0)
(1, 99)
(2, 56)
(3, 56)
(5, 0) 3 5 6
Egress Routing Table 99 56

40. MPLS Architecture MPLS has two major components:
Control plane: Exchanges Layer 3 routing information and labels
Data plane: Forwards packets based on labels
Control plane contains complex mechanisms to exchange routing information, such as OSPF, EIGRP, IS-IS, and BGP, and to exchange labels, such as TDP, LDP, BGP, and RSVP.
Data plane has a simple forwarding engine.

41. MPLS Architecture (Cont.)
Router functionality is divided into two major parts: control plane and data plane

42. MPLS Architecture (Cont.)
Router functionality is divided into two major parts: control plane and data plane

43. MPLS Architecture (Cont.)
Router functionality is divided into two major parts: control plane and data plane

44. MPLS Architecture (Cont.)
Router functionality is divided into two major parts: control plane and data plane

45. MPLS Architecture (Cont.)
Router functionality is divided into two major parts: control plane and data plane

46. Network Architecture of Project 1
Depending on the traffic expectations, the locations are divided into two categories, A & B.
A locations are provided with core routers.
B locations are provided with only edge routers.

47. Location A
A is further divided into four categories viz A1, A2, A3, A4
All A nodes are provided with Cisco routers.

48. BSNL NIB-II CORE ROUTER A1,A2,A3 &A4
CONNECTIVITY DIAGRAM
LEGENDS
STM-16 LINK
A1 Nodes - 5
STM-1 LINK
Allahabad
A2+A3 Nodes - 9
Chandigarh
A4 Nodes - 10
CISCO ROUTER
JUNIPER ROUTER
(Existing with BSNL)
Lucknow
Guwahati
Patna
Jullundar
Jaipur
Ranchi
Noida
Ahmedabad
Indore
Manglore
Kolkata
Bhubneshwar
Mumbai
Nagpur
Pune
Coimbtore
Banglore
Chennai
Ernakulam
Vijaywada
Raipur
Hyderabad

49. B Nodes B locations are divided into B1 & B2 categories.
Provided with only edge routers Cisco 7613
B1 & B2 are dual homed to nearest A node on STM-1 link.

50. ROUTER CONNECTIVITY DIAGRAM
NIB-II A1,A2,A3,A4,B1& B2
ROUTER CONNECTIVITY DIAGRAM
A1 Nodes - 5
A2+A3 Nodes - 9
A4 Nodes - 10
B1 + B2 Nodes - 47
Jullundar
Jaipur
Pune
Ahmedabad
Indore
Lucknow
Patna
Noida
Kolkata
Chennai
Banglore
Mumbai
Ernakulam
Hyderabad
Chandigarh
Manglore
Bhubneshwar
Ranchi
Allahabad
Coimbtore
Madurai
Trichy
Palghat
Trivandrum
Trichur
Kalikat
Vijaywada
Rajmundary
Vizag
Tirupati
Durgapur
Siliguri
Dimapur
Guwahati
Kalyan
Panjim
Aurangabad
Kolhapur
Nashik
Nagpur
Bhopal
Gwalior
Mehsana
Ambala
Faridabad
Gurgaon
Meerut
Agra
Dehradun
Ludhiana
Ferozpur
Shimla
Amritsar
Ajmer
Jodhpur
Mysore
Hubli
Jamshedpur
Surat
Vadodara
Rajkot
Jabalpur
Shilong
Ghaziabad
Varanasi
Kanpur
Pondicherry
Belgaum
Raipur

51. Routers Connectivity Noida Mumbai Kolkata Chennai Route Reflector
Jaipur
Jallandar
Lucknow
Ahmedabad
Patna 3
Noida
Mumbai
Kolkata
NIB - II Core Router
IXP Router
Route Reflector
IDC Router
IGW Router
Chennai
Bangalore
Indore 1
Ernakulam
Pune 51
Hyderabad 51

52. Review Drawbacks of Traditional IP Routing Basic MPLS Concepts
MPLS Labels
MPLS Architecture
Label Switch Routers
Label database
Label operations
Lesson Aim
<Enter lesson aim here.>

53. Thank You
Lesson Aim
<Enter lesson aim here.>