Cisco Systems 12.4 manual Mpls LDP Session Protection Customizations

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MPLS LDP Session Protection Customizations

Information About MPLS LDP Session Protection

•If the LSR is one hop from its neighbor, it is directly connected to its neighbor. The LSR sends out LDP Hello messages as User Datagram Protocol (UDP) packets to all the routers on the subnet. The hello message is called an LDP Link Hello. A neighboring LSR responds to the hello message and the two routers begin to establish an LDP session.

•If the LSR is more than one hop from its neighbor, it is not directly connected to its neighbor. The LSR sends out a directed hello message as a UDP packet, but as a unicast message specifically addressed to that LSR. The hello message is called an LDP Targeted Hello. The nondirectly connected LSR responds to the Hello message and the two routers establish an LDP session. (If the path between two LSRs has been traffic engineered and has LDP enabled, the LDP session between them is called a targeted session.)

MPLS LDP Session Protection uses LDP Targeted Hellos to protect LDP sessions. Take, for example, two directly connected routers that have LDP enabled and can reach each other through alternate IP routes in the network. An LDP session that exists between two routers is called an LDP Link Hello Adjacency. When MPLS LDP Session Protection is enabled, an LDP Targeted Hello Adjacency is also established for the LDP session. If the link between the two routers fails, the LDP Link Adjacency also fails. However, if the LDP peer is still reachable through IP, the LDP session stays up, because the LDP Targeted Hello Adjacency still exists between the routers. When the directly connected link recovers, the session does not need to be reestablished, and LDP bindings for prefixes do not need to be relearned.

•MPLS LDP Session Protection Customizations, page 32

MPLS LDP Session Protection Customizations

You can modify MPLS LDP Session Protection by using the keywords in the mpls ldp session protection command.

Specifying How Long an LDP Targeted Hello Adjacency Should Be Retained

The default behavior of the mpls ldp session protection command allows an LDP Targeted Hello Adjacency to exist indefinitely following the loss of an LDP Link Hello Adjacency. You can issue the duration keyword to specify the number of seconds (from 30 to 2,147,483) that the LDP Targeted Hello Adjacency is retained after the loss of the LDP Link Hello Adjacency. When the link is lost, a timer starts. If the timer expires, the LDP Targeted Hello Adjacency is removed.

Specifying Which Routers Should Have MPLS LDP Session Protection

The default behavior of the mpls ldp session protection command allows MPLS LDP Session Protection for all neighbor sessions. You can issue either the vrfor for keyword to limit the number of neighbor sessions that are protected.

Enabling MPLS LDP Session Protection on Specified VPN Routing and Forwarding Instances

If the router is configured with at least one VPN routing and forwarding (VRF) instance, you can use the vrf keyword to select which VRF is to be protected. You cannot specify more than one VRF with the mpls ldp session protection command. To specify multiple VRFs, issue the command multiple times.

Enabling MPLS LDP Session Protection on Specified Peer Routers

You can create an access list that includes several peer routers. You can specify that access list with the for keyword to enable LDP Session Protection for the peer routers in the access control list.

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 Information About Mpls LDP Finding Feature InformationPrerequisites for Mpls LDP LDP and TDP Support Introduction to Mpls LDPMpls LDP Functional Overview 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 AutoconfigurationMpls LDP Autoconfiguration on Ospf and IS-IS Interfaces Information About Mpls LDP AutoconfigurationHow to Configure Mpls LDP Autoconfiguration 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.
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