Cisco 10000-2P2-2DC Software Guide - Page 399

20 C H A P T E R Configuring L2 Virtual Private Networks OL-2226-23 To improve profitability, service providers (SPs) introduce new services to reduce operational expenditures. To reduce the number of managed networks, use network convergence, a multiphase transition of the network. This affects both the core and edge/aggregation side. The technology is predominantly Multiprotocol Label Switching (MPLS) based core networks. However, IP cores are the service of choice in a number of large SPs. Both the IP and the MPLS cores carry multiservice traffic. The edges of the network is constructed with network elements providing a single network element for convergence between Layer 2 and Layer 3 services. The following Layer 2 virtual private network (L2VPN) solutions enable existing or emerging Layer 2 transport technology to interwork through converged MPLS or IP core networks. • Virtual Private Wire Services (VPWS)-A point-to-point service consisting of individual point-to-point connections cross-connected to native interfaces. • Virtual Private LAN Services (VPLS)-A service consisting of a set of point-to-multipoint connections. L2VPN features are of the VPWS type and are designed for the benefit of the carriers. L2VPN features allow for a transparent use of network resources, and a way of reducing the number of networks that need managing. Cisco nonstop forwarding (NSF) with stateful switchover (SSO) is effective at increasing availability of network services. Cisco NSF with SSO provides continuous packet forwarding, even during a network processor hardware or software failure. In a redundant system, the secondary processor recovers control plane service during a critical failure in the primary processor. SSO synchronizes network state information between the primary and the secondary processor." Any Transport over MPLS (AToM) uses NSF, SSO, and Graceful Restart to allow a route processor (RP) to recover from a disruption in control plane service without losing the MPLS forwarding state. In Cisco IOS Release 12.2(33) SB, the L2VPN features support NSF/SSO. See the "NSF and SSO-L2VPN" section on page 20-6. Cisco 10000 series routers also support the following two L2VPN technology solutions: • Local Switching (LS)-The ordered duple . This is the point-to-point interconnection of two attachment circuits within a Cisco 10000 series router chassis. Also, two attachment circuits (ACs) can be of: - The same type-Creating a like-to-like LS connection. - A distinct type-Creating an any-to-any LS connection. • AToM-The ordered triple . This is the point-to-point interconnection of two attachment circuits in separate Cisco 10000 series router chassis through a pseudowire (MPLS). Also, two ACs can be of the same type in which case a like-to-like AToM connection exists. Or, two ACs can be of a distinct type, in which case an any-to-any AToM connection exists. Cisco 10000 Series Router Software Configuration Guide 20-1