Cisco IOS Wide-Area Networking Configuration Guide - Free Books

OAM Transparent ModeIn OAM transparent mode, the PEs will pass the following OAM cells transparently across thepseudowire:• F5 segment and end-to-end Fault Management (FM) OAM cells• RM OAM cells, except Performance Management (PM) and Security OAM cellsNoteThe Cisco 7200 and the Cisco 7500 ATM driver cannot forward RM cells over the PSN for ABRToS. The RM cells are locally terminated.VPI or VPI/VCI rewrite is not supported for any ATM transport mode. Both pairs of PE to CE peerrouters must be configured with matching VPI and VCI values except in OAM local emulation mode.For example, if PE1 and CE1 are connected by PVC 10/100, PE2 and CE2 should also be connected byPVC 10/100.OAM Local Emulation ModeIn OAM Local Emulation mode, OAM cells are not passed through the pseudowire. All F5 OAM cellsare terminated and handled locally. On the L2TPv3-based pseudowire, the CE device sends an SLImessage across the pseudowire to notify the peer PE node about the defect, rather than tearing down thesession. The defect can occur at any point in the link between the local CE and the PE. OAMmanagement can also be enabled on the PE node using existing OAM management configurations.IPv6 Protocol DemultiplexingUpgrading a service provider network to support IPv6 is a long and expensive process. As an interimsolution, the Protocol Demultiplexing for L2TPv3 feature introduces the ability to provide native IPv6support by setting up a specialized IPv6 network and offloading IPv6 traffic from the IPv4 network. IPv6traffic is transparently tunneled to the IPv6 network using L2TPv3 pseudowires without affecting theconfiguration of the CE routers. IPv4 traffic is routed as usual within the IPv4 network, maintaining theexisting performance and reliability of the IPv4 network.Figure 3 shows a network deployment that offloads IPv6 traffic from the IPv4 network to a specializedIPv6 network. The PE routers demultiplex the IPv6 traffic from the IPv4 traffic. IPv6 traffic is routed tothe IPv6 network over an L2TPv3 pseudowire, while IPv4 traffic is routed normally. The IPv4 PE routersmust be configured to demultiplex incoming IPv6 traffic from IPv4 traffic. The PE routers facing theIPv6 network do not require demultiplexing configuration.46