Cisco Systems 12.4 manual Introduction to LDP Sessions, Train and Release LDP/TDP Support

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Introduction to LDP Sessions

Directly Connected MPLS LDP Sessions

Train and Release

LDP/TDP Support

 

 

12.2S, SB, and SR Trains

• LDP is enabled by default.

 

 

• Cisco IOS Release 12.2(25)S and earlier releases: TDP is

 

supported for LDP features.

 

• Cisco IOS Releases 12.2(27)SBA, 12.2(27)SRA,

 

12.2(27)SRB and later releases: TDP is not supported for

 

LDP features.

 

 

12.T/Mainline Trains

• Cisco IOS Release 12.3(14)T and earlier releases: TDP is

 

 

enabled by default.

 

• Cisco IOS Releases 12.4 and 12.4T and later releases:

 

LDP is enabled by default.

 

• Cisco IOS Release 12.3(11)T and earlier releases: TDP is

 

supported for LDP features.

 

• Cisco IOS Release 12.3(14)T and later releases: TDP is

 

not support ed for LDP features.

 

 

Introduction to LDP Sessions

When you enable MPLS LDP, the LSRs send out messages to try to find other LSRs with which they can create LDP sessions. The following sections explain the differences between directly connected LDP sessions and nondirectly connected LDP sessions.

•Directly Connected MPLS LDP Sessions, page 3

•Nondirectly Connected MPLS LDP Sessions, page 4

Directly Connected MPLS LDP Sessions

If an LSR is one hop from its neighbor, it is directly connected to its neighbor. The LSR sends out LDP link Hello messages as User Datagram Protocol (UDP) packets to all the routers on the subnet (multicast). A neighboring LSR may respond to the link Hello message, allowing the two routers to establish an LDP session. This is called basic discovery.

To initiate an LDP session between routers, the routers determine which router will take the active role and which router will take the passive role. The router that takes the active role establishes the LDP TCP connection session and initiates the negotiation of the LDP session parameters. To determine the roles, the two routers compare their transport addresses. The router with the higher IP address takes the active role and establishes the session.

After the LDP TCP connection session is established, the LSRs negotiate the session parameters, including the method of label distribution to be used. Two methods are available:

•Downstream Unsolicited: An LSR advertises label mappings to peers without being asked to.

•Downstream on Demand: An LSR advertises label mappings to a peer only when the peer asks for them.

For information about creating LDP sessions, see the Enabling Directly Connected LDP Sessions, page 6.

MPLS LDP Configuration Guide, Cisco IOS Release 12.4

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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 Finding Feature Information Prerequisites for Mpls LDPInformation About Mpls LDP Mpls LDP Functional Overview Introduction to Mpls LDPLDP and TDP Support Train and ReleaseTrain and Release LDP/TDP Support Introduction to LDP SessionsNondirectly Connected Mpls LDP Sessions Enabling Directly Connected LDP Sessions, How to Configure Mpls LDPStep Command or Action Purpose Enabling Directly Connected LDP SessionsExample Step Command or Action PurposeStep Command or Action Establishing Nondirectly Connected Mpls LDP SessionsExamples 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 Following example displays the LDP router ID Preserving QoS Settings with Mpls LDP Explicit NullInterface 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 Configuring Directly Connected Mpls LDP Sessions Example Mpls LDP Configuration ExamplesRouter 1 Configuration Router 2 ConfigurationRouter 3 Configuration Establishing Nondirectly Connected Mpls LDP Sessions Example Router 4 Configuration Router 5 ConfigurationRouter 6 Configuration Additional References Technical Assistance Description Link Feature Information for Mpls Label Distribution ProtocolRouter-id Releases Feature InformationFeature Name Releases Feature Name Releases Feature Information Page Information About Mpls LDP Session Protection Restrictions for Mpls LDP Session ProtectionMpls LDP Session Protection Customizations Enabling Mpls LDP Session Protection How to Configure Mpls LDP Session ProtectionRouterconfig-if#mpls label protocol ldp Verifying Mpls LDP Session Protection Router# show mpls ldp neighbor detail Troubleshooting TipsIp classless Redundancy Full-duplex Interface Ethernet5/0/2 RFCs Title MIBs MIBs LinkCommand Reference Restrictions Mpls LDP Inbound Label Binding FilteringConfiguring Mpls LDP Inbound Label Binding Filtering How to Configure Mpls LDP Inbound Label Binding FilteringIp access-list standard access-list-number Router# show mpls ldp neighbor 10.12.12.12 detail Verifying that Mpls LDP Inbound Label Bindings are FilteredAccess-list-number Access-list-name LDP Specification, draft-ietf-mpls-ldp-08.txt Technical Assistance Description Link Glossary Releases Feature InformationMpls LDP Inbound Label Binding Filtering Page Restrictions for Mpls LDP Autoconfiguration Mpls LDP AutoconfigurationHow to Configure Mpls LDP Autoconfiguration Information About 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 Command or Action Purpose Step Configuring Mpls LDP Autoconfiguration with IS-IS InterfacesEnables IS-IS for IP on the interface Enables the LDP for interfaces that belong to an IS-IS Router# show isis mpls ldp Verifying Mpls LDP Autoconfiguration with IS-ISTroubleshooting Tips Mpls LDP Autoconfiguration with Ospf ExampleCommand Reference Mpls LDP Autoconfiguration with IS-IS ExamplesFeature Information for Mpls LDP Autoconfiguration Feature Information for Mpls LDP Autoconfiguration Mpls LDP Graceful Restart How Mpls LDP Graceful Restart Works Information About Mpls LDP Graceful RestartConfiguring Mpls LDP Graceful Restart How to Configure Mpls LDP Graceful RestartMpls ip Mpls label protocol ldptdpboth Verifying the Configuration Configuration Example for Mpls LDP Graceful RestartRouter 2 configured with LDP SSO/NSF Router 1 configured with LDP GRMpls label protocol ldp mpls traffic-eng tunnels mpls ip Router 3 configured with LDP SSO/NSFMpls 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.
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