MPLS MultiProtocol Label Switching

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

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.

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).

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.

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.

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.

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.

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.

Basic MPLS Concepts (Cont.) Example

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

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.

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

SHIM Layer N D P 3 2 1 MPLS

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

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

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.

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.)

MPLS Labels (Cont.)

MPLS Labels (Cont.)

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

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.

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.

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.

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

Label Switch Routers (Cont.) Architecture of Edge LSRs

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

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

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

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

MPLS Label Assignment/Binding Label Request for FEC 10.0.0.0 Upstream LDP peer Net: 10.0.0.0 Label: 17 Advertise incoming label Net: 10.0.0.0 Label: 52 (3, 29) Net: 10.0.0.0 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)

Label Operations PUSH SWAP POP

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

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

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

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

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

MPLS Forwarding Example 1 2 Ingress Routing Table Destination Next Hop 134.5/16 200.3.2/24 (2, 84) (3, 99) MPLS Table In Out (6, 0) (1, 99) (2, 56) (3, 56) (5, 0) 3 5 6 134.5.1.5 200.3.2.7 200.3.2.1 134.5.6.1 Egress Routing Table 200.3.2.7 99 200.3.2.7 200.3.2.7 200.3.2.7 56 200.3.2.7

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.

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

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

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

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

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

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.

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

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

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.

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

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

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.>

Thank You Lesson Aim <Enter lesson aim here.>