Cisco Systems 12.4 Introduction to Mpls LDP, Mpls LDP Functional Overview, LDP and TDP Support

Page 8

Introduction to MPLS LDP

Information About MPLS LDP

Introduction to MPLS LDP

MPLS LDP provides the means for LSRs to request, distribute, and release label prefix binding information to peer routers in a network. LDP enables LSRs to discover potential peers and to establish LDP sessions with those peers for the purpose of exchanging label binding information.

MPLS LDP enables one LSR to inform another LSR of the label bindings it has made. Once a pair of routers communicate the LDP parameters, they establish a label-switched path (LSP). MPLS LDP enables LSRs to distribute labels along normally routed paths to support MPLS forwarding. This method of label distribution is also called hop-by-hop forwarding. With IP forwarding, when a packet arrives at a router the router looks at the destination address in the IP header, performs a route lookup, and forwards the packet to the next hop. With MPLS forwarding, when a packet arrives at a router the router looks at the incoming label, looks up the label in a table, and then forwards the packet to the next hop. MPLS LDP is useful for applications that require hop-by-hop forwarding, such as MPLS VPNs.

MPLS LDP Functional Overview

Cisco MPLS LDP provides the building blocks for MPLS-enabled applications, such as MPS Virtual Private Networks (VPNs).

LDP provides a standard methodology for hop-by-hop, or dynamic label, distribution in an MPLS network by assigning labels to routes that have been chosen by the underlying Interior Gateway Protocol (IGP) routing protocols. The resulting labeled paths, called label switch paths (LSPs), forward label traffic across an MPLS backbone to particular destinations. These capabilities enable service providers to implement MPLS-based IP VPNs and IP+ATM services across multivendor MPLS networks.

LDP and TDP Support

LDP supercedes Tag Distribution Protocol (TDP). See the table below for information about LDP and TDP support in Cisco IOS releases.

Use caution when upgrading the image on a router that uses TDP. Ensure that the TDP sessions are established when the new image is loaded. You can accomplish this by issuing the global configuration command mpls label protocol tdp. Issue this command and save it to the startup configuration before loading the new image. Alternatively, you can enter the command and save the running configuration immediately after loading the new image.

Table 1

LDP and TDP Support

Train and Release

12.0S Train

LDP/TDP Support

•TDP is enabled by default.

•Cisco IOS Release 12.0(29)S and earlier releases: TDP is supported for LDP features.

•Cisco IOS Release 12.0(30)S and later releases: TDP is not support for LDP features.

MPLS LDP Configuration Guide, Cisco IOS Release 12.4

2

Page 7 Page 9
Image 8
Page 7 Page 9
Contents Mpls LDP Configuration Guide, Cisco IOS Release Page N T E N T S Mpls LDP Inbound Label Binding Filtering Mpls LDP Graceful Restart Contents Mpls LDP Configuration Guide, Cisco IOS Release Information About Mpls LDP Finding Feature InformationPrerequisites for Mpls LDP Introduction to Mpls LDP Mpls LDP Functional OverviewLDP and TDP Support Train and ReleaseIntroduction to LDP Sessions Train and Release LDP/TDP SupportNondirectly Connected Mpls LDP Sessions How to Configure Mpls LDP Enabling Directly Connected LDP Sessions,Example Step Command or Action PurposeEnabling Directly Connected LDP Sessions Command or Action Purpose StepExamples Step Command or ActionEstablishing Nondirectly Connected Mpls LDP Sessions Mpls label protocol ldp tdp both Interface tunnelnumber Tunnel destination ip-address Saving Configurations Mpls Tag Switching Commands Specifying the LDP Router ID Routerconfig# mpls ldp Router-id pos2/0/0 Preserving QoS Settings with Mpls LDP Explicit Null Following example displays the LDP router IDInterface type number Command or Action Purpose Local Outgoing Prefix Protecting Data Between LDP Peers with MD5 Authentication Summary Steps Mpls ldp neighbor vrf vpn-nameip Mpls LDP Configuration Examples Configuring Directly Connected Mpls LDP Sessions ExampleRouter 3 Configuration Router 1 ConfigurationRouter 2 Configuration Establishing Nondirectly Connected Mpls LDP Sessions Example Router 6 Configuration Router 4 ConfigurationRouter 5 Configuration Additional References Feature Information for Mpls Label Distribution Protocol Technical Assistance Description LinkReleases Feature Information Router-idFeature Name Releases Feature Name Releases Feature Information Page Restrictions for Mpls LDP Session Protection Information About Mpls LDP Session ProtectionMpls LDP Session Protection Customizations How to Configure Mpls LDP Session Protection Enabling Mpls LDP Session ProtectionRouterconfig-if#mpls label protocol ldp Verifying Mpls LDP Session Protection Troubleshooting Tips Router# show mpls ldp neighbor detailIp classless Redundancy Full-duplex Interface Ethernet5/0/2 MIBs MIBs Link RFCs TitleCommand Reference Mpls LDP Inbound Label Binding Filtering RestrictionsHow to Configure Mpls LDP Inbound Label Binding Filtering Configuring Mpls LDP Inbound Label Binding FilteringIp access-list standard access-list-number Verifying that Mpls LDP Inbound Label Bindings are Filtered Router# show mpls ldp neighbor 10.12.12.12 detailAccess-list-number Access-list-name LDP Specification, draft-ietf-mpls-ldp-08.txt Technical Assistance Description Link Releases Feature Information GlossaryMpls LDP Inbound Label Binding Filtering Page Mpls LDP Autoconfiguration Restrictions for Mpls LDP AutoconfigurationInformation About Mpls LDP Autoconfiguration How to Configure Mpls LDP AutoconfigurationMpls LDP Autoconfiguration on Ospf and IS-IS Interfaces Configuring Mpls LDP Autoconfiguration with Ospf InterfacesGlobally enables hop-by-hop forwarding Router ospf process-id Verifying Mpls LDP Autoconfiguration with Ospf Router# show mpls interfaces Serial 2/0 detail Configuring Mpls LDP Autoconfiguration with IS-IS Interfaces Command or Action Purpose StepEnables IS-IS for IP on the interface Enables the LDP for interfaces that belong to an IS-IS Verifying Mpls LDP Autoconfiguration with IS-IS Router# show isis mpls ldpMpls LDP Autoconfiguration with Ospf Example Troubleshooting TipsMpls LDP Autoconfiguration with IS-IS Examples Command ReferenceFeature Information for Mpls LDP Autoconfiguration Feature Information for Mpls LDP Autoconfiguration Mpls LDP Graceful Restart Information About Mpls LDP Graceful Restart How Mpls LDP Graceful Restart WorksHow to Configure Mpls LDP Graceful Restart Configuring Mpls LDP Graceful RestartMpls ip Mpls label protocol ldptdpboth Configuration Example for Mpls LDP Graceful Restart Verifying the ConfigurationRouter 1 configured with LDP GR Router 2 configured with LDP SSO/NSFRouter 3 configured with LDP SSO/NSF Mpls label protocol ldp mpls traffic-eng tunnels mpls ipMpls Label Distribution Protocol Feature Information for Mpls LDP Graceful Restart Feature Information for Mpls LDP Graceful Restart

12.4 specifications

Cisco Systems has consistently been at the forefront of networking technology, and one of its notable software releases is IOS version 12.4. This version introduced significant enhancements and features that continue to influence networking practices. IOS 12.4 was specifically designed to accommodate the growing demands of network reliability, scalability, and advanced functionalities.

One of the primary characteristics of IOS 12.4 is its enhanced security features. The version integrates advanced security protocols, including improvements in IPsec, which allows for secure communication across potentially insecure networks. Additionally, it supports firewall technologies and access control lists (ACLs), ensuring that organizations can implement stringent security measures tailored to their traffic requirements.

Another defining feature of IOS 12.4 is its support for IPv6. As the internet continued to grow, the need for expanded address space became critical. With IOS 12.4, Cisco provided robust capabilities for transitioning from IPv4 to IPv6, ensuring that network managers could adopt the newer standard without sacrificing performance or reliability. This included support for routing protocols and other networking functions that were essential in an IPv6 environment.

Performance improvements were also a key aspect of IOS 12.4. The release optimized routing protocols, including Enhanced Interior Gateway Routing Protocol (EIGRP) and Open Shortest Path First (OSPF), to enhance convergence times and reduce latency. This effectively contributed to improved network efficiency and uptime.

Cisco also included advanced Quality of Service (QoS) capabilities in IOS 12.4, allowing organizations to prioritize critical traffic. Features such as class-based weighted fair queuing and low-latency queuing became invaluable for organizations requiring seamless voice and video communications over IP networks. This focus on QoS demonstrated Cisco's understanding of the growing importance of multimedia applications in modern business environments.

With a set of stable and scalable routing features, IOS 12.4 supports a variety of platforms, enabling businesses to deploy it across different networking hardware to suit their needs. The modularity of this IOS version makes it flexible for various applications, from small business networks to large enterprise systems.

In summary, Cisco Systems' IOS 12.4 brought forth a wealth of features aimed at enhancing security, performance, and flexibility. Through improved routing capabilities, strong IPv6 support, and advanced QoS features, this version laid the foundation for many of the networking principles that organizations still utilize today.
Top Page Image Contents