Optical UNI

The Optical Internetworking Forum (OIF) is the standards body that is developing an Optical User Network Interface (O-UNI), which provides an interface between optical clients and an optical network. The O-UNI defines a link for communicating control, signaling, and data packets between the optical client (such as an IP router) and the adjacent optical transport-networking device (such as an OXC). The O-UNI was created so that carriers could offer a simple, open, external interface for...

Figure 33 Label Forwarding Information Base LFIB

Outgoing label Outgoing interface Next hop address Outgoing label Outgoing interface Next hop address Outgoing label Outgoing interface Next hop address Outgoing label Outgoing interface Next hop address Outgoing label Outgoing interface Next hop address Outgoing label Outgoing Interface Next hop address Label forwarding information base (LFIB) structure Each subentry consists of an outgoing label, outgoing interface, and next-hop address. Subentries within an individual entry may have the same...

WAN Technologies and MPLS

This chapter covers the following topics Inside the Cloud This section describes circuit, packet, and cell switching technologies. A fundamental understanding of existing WAN switching technologies will enhance your understanding of MPLS technology as applied to wide-area technology. Layer 3 Routing This section describes the forwarding and control components of the routing function and Forwarding Equivalence Classes (FECs). Label Switching An introduction to label switching and MPLS is...

Forwarding Equivalency Class

Forwarding Equivalency Class (FEC) is a set of Layer 3 packets that are forwarded in the same manner over the same path with the same forwarding treatment. While assigning a packet to an FEC, the router might look at the IP header and also some other information, such as the interface on which this packet arrived. FECs might provide a coarse or fine forwarding granularity based on the amount of information considered for setting the equivalence. A set of unicast packets whose Layer 3...

Advantages of MPLS Traffic Engineering

MPLS traffic engineering features allow an MPLS backbone to replicate and expand upon the traffic engineering capabilities of Layer 2 ATM and Frame Relay networks. Traffic engineering is essential for service provider and Internet service provider backbones. Both backbones must support a high use of transmission capacity, and the networks must be very resilient so that they can withstand link or node failures. The following are the advantages of MPLS traffic engineering With MPLS, traffic...

ATMBased Mpls Vpns

In an ATM-based MPLS configuration, ATM Forum PVCs are unnecessary. MPLS LVCs are automatically brough the switch has its resources partitioned for LVCs and other parameters have been appropriately set up. The VPN feature of MPLS allows several sites to transparently interconnect through a service provider's network. O service provider network can support several differentIP VPNs. Each of these VPNs appears to its users as a closed group private network, separate from all other networks. Within...

HSRP Support Between Two VRF Interfaces

Figure 5-18 illustrates HSRP support between the two VRF interfaces belonging to PE1 and PE2. The CE uses the virtual IP address of 10.10.10.10 as the next-hop address for its default static route. The real IP addresses of 10.10.10.1 and 10.10.10.2 are configured on PE1 and PE2. PE1 can be prioritized to remain active, and PE2 is in standby mode. The serial interfaces to the P router are tracked. This ensures that the links that experience a greater number of flaps will be automatically...

Committed Information Rate CIR

Another parameter, called the Committed Information Rate (CIR), defines an agreement between the carrier and the customer regarding the delivery of data on a particular VC. CIR is measured in bits per second. It measures the average amount of data over a specific period of time, such as 1 second, that the network will attempt to deliver with a normal priority. In the event of congestion, data bursts that exceed the CIR are marked as Discard Eligible (DE) and are delivered at lower priority or...

Optical Cross Connect

The Optical Cross-Connect (OXC) is a DWDM system component that provides cross-connect switching functionality between n input ports and n output ports, each handling a bundle of multiplexed single-wavelength signals. The OXC permits bandwidth management and supports network reconfiguration. The OXC lets service providers transport and manage wavelengths efficiently at the optical layer. An OXC contains a bit-rate and format-independent optical switch that helps it cross-connect over multiple...

Local Management Interface LMI Status Polling

The operational support protocol for the UNI is called the Local Management Interface (LMI). The LMI standards in use are ANSI T1.617 Annex D, Q.933 Annex A, and the Cisco LMI. The LMI defines a polling protocol between the FRAD and the Frame Relay switch. The FRAD periodically issues a STATUS ENQUIRY message, and the Frame Relay switch should respond with a STATUS message. The polling period is a negotiable parameter, with a default of 10 seconds. The LMI verifies link integrity, status of...

Dense Wavelength Division Multiplexing

Conventional fiber-optic systems use a single wavelength or color injected by an optical transmitter that is a light-emitting diode (LED) in the case of multimode fiber (MMF) or a laser diode in the case of single-mode fiber (SMF). Laser diodes or LEDs perform an electrical-to-optical (EO) conversion of the electrical signal. The light is injected at a precise angle into the core of the fiber-optic cable using a lens, which has a higher refractive index than the cladding. Light pulses are...

Appendix B Mpls Equipment Design Specifications

The selection of edge and core LSR equipment depends on the design and capacity planning of the service provider core network. The tables in this appendix provide equipment specifications that help the MPLS network designer select equipment based on the service type, access, and redundancy options incorporated in the design. Table B-1. MPLS ATM-Edge Equipment Specifications Relatively small numbers of async, modem, serial Frame Relay, 10-Mbps Ethernet, ISDN BRI and PRI, HSSI, E1 T1 serial, Fast...

Figure 814 Example of Mpls Vpn QoS Hose Model

The service provider also supplies VPN1 with certain guarantees of up to 45 Mbps for traffic sent by site 2 and site 3 to site 1 (site 1 ECR 45 Mbps). This traffic could be directed to site 1 from site 2 or site 3 or distributed in an arbitrary way between site 2 and site 3 and sent to site 1. In VPN2, the service provider supplies certain guarantees of up to 20 Mbps for traffic sent by site 1 to site 2 (site 1 ICR 20 Mbps). Site 1 also has an ECR of 20 Mbps, which means that site 2 can send...

Optimized Rerouting

Fast rerouting can result in suboptimal traffic-engineered paths. The key is to dynamically respond to failure as well as to new or restored paths. Thus, when a failure is detected, it is necessary to also notify the headend of the LSP tunnel. The headend can then compute a more optimal path. Traffic can then be diverted to the new LSP tunnel. This can be done without further disruption. Often missing from Layer 2 networks is a feature called bridge-and-roll or make-before-break. This is the...

MPLS Backbone Link Sizing

The following steps detail the procedures involved with MPLS backbone link sizing Step 2. Estimate traffic from each point of presence. Step 3. Estimate the unidirectional traffic matrix. Step 4. Estimate the bidirectional traffic matrix. Step 5. Design the backbone trunk topology. Step 6. Calculate estimated link bandwidths. The first step in MPLS network design is to select the size, type, and layout of the PoPs according to the considerations described in the previous section. The edge PoPs...

Appendix A Mpls Command Reference

This MPLS command reference provides tables that document the commonly used MPLS commands. Cisco's prestandard equivalent tag-switching commands are provided, along with their MPLS counterparts. Sample usage of many of these commands can be found in the case studies and examples throughout this book. For sample usage of the remaining commands listed here, refer to the IOS Command Reference and Configuration Guide. These documents are available on Cisco's documentation CD-ROM and on Cisco...

Layer 3 Routing Design

MPLS uses link-state routing protocols such as OSPF and IS-IS to determine the routes for IP traffic and LVCs. LSRs run IP routing protocols in the same way that regular IP routers do. Designing IP routing in an MPLS network is almost exactly the same process as designing IP routing for an ordinary IP network. The network can be depicted in a logical topology, and a routing topology can be ascertained. By looking at the routing topology, you can divide the network into areas, design route...

Integration of IP and ATM

The early proponents and developers of ATM envisioned it to be a ubiquitous technology, spanning the desktop, LAN, and WAN. Today, few people still cling to that vision. Instead, IP has proliferated with the explosion of the Internet. The concept of IP over anything has taken precedence over the focus on forcing ATM to behave like a legacy LAN protocol. ATM on the LAN, driven by LANE (LAN Emulation), classical IP over ATM, and MPOA (multiprotocol over ATM), has seen limited growth and has been...

New Forwarding Paradigm

From a technology perspective, the Internet has impacted our lives more than anything in the last century. Today, we see wireless handheld devices, Internet appliances, Voice over IP (VoIP) phones, webcast video, PCs, hosts, and even mainframe traffic over the Internet. The sheer growth due to the emergence of the World Wide Web has propelled IP to the forefront of data communications. Carriers and service providers are in a constant state of backbone capacity expansion. More recently, with the...

PoP Design

Point of presence (PoP) design constraints include the choice of access line type and equipment for the network. The location of PoPs is largely determined by user traffic and the location of population centers. Proper capacity planning must be performed prior to PoP design. The capacity-planning phase should make proper estimates and approximations for future traffic growth based on the existing customer base and anticipated customer growth and corresponding traffic growth. Oversubscription...

Packet Based Mpls Vpns

This chapter covers the following topics MPLS VPN Operation MPLS Virtual Private Networks can be built over existing Layer 2 infrastructures. This section details the various MPLS VPN building blocks and the interaction between the various MPLS elements. This section also explains VPN route target communities, distribution of VPN routing information, and MPLS forwarding. The various packet-based MPLS LSR commands used to build VPN networks are explained. These commands are later exemplified in...

Multiprotocol Lambda Switching

Multiprotocol Lambda Switching (MP .S) is the optical analogy of MPLS. The MPLS control plane performs all crucial control functions for MPLS data networks. MPLS RSVP-TE extensions or CR-LSDP extensions can be applied to optical networks to unify the control plane for optical network elements. MP .S approaches the design of control planes for OXC switches and other integrated multifunctional optical switches that leverage existing control-plane techniques developed for MPLS traffic engineering....