Cisco IOS Wide-Area Networking Configuration Guide - Free Books

ATM OAM CellsThe SIP-400 linecard supports ATM OAM cells operating at VP and VC levels. F4 cells operate at theVP level. They use the same VPI as the user data cells. However, they use two different reserved VCIs,as follows:• VCI = 3 Segment OAM F4 cells• VCI = 4 End-to-end OAM F4 cellsOAM F5 cells operate at the VC level. They use the same VPI and VCI as the user cells. To distinguishbetween data and OAM cells, the PTI field is used as follows:• PTI = 100 (4) Segment OAM F5 cells processed by the next segment• PTI =101 (5) End-to-end OAM F5 cells which are only processed by end stations terminating anATM linkIn the ingress direction (CE to PE), because of OAM emulation not supported in the 12.2(33)SRCrelease, all OAM cells are handled the same as data cells on the SIP-400 linecard. Both segment andend-to-end OAM F4/F5 cells are tunneled over L2TPv3 to the remote PE device. They are senttransparently across the IP core in L2TPv3 tunnels.In the egress direction (PE to CE), the SIP-400 linecard sends all OAM cells to the CE device similar tosending ATM data cells.Loopback Interface ReservationYou must reserve a loopback interface used as a source of the L2TPv3 tunnel for a particular linecard toprevent it from being used across multiple linecards. These loopback interfaces host the local IPaddresses used by the L2TP tunnels. A minimum of one such IP address is needed for every CE-facinglinecard. In most cases, you must create multiple loopback interfaces to accommodate routing protocolconfiguration and L2TPv3 configuration. Also, you must explicitly use the mpls ldp router-id commandto avoid LDP router ID changes after system reload.To reserve a loopback interface, use the following command on the route processor in interfaceconfiguration mode:mls reserve l2tpv3 slot slot-number [processor processor-number]This command binds the loopback interface to the specified slot/NP. Once configured, the loopbackcannot be used to configure L2TPv3 tunnels on other LC/NPs. You must create another loopbackinterface in order to configure an L2TPv3 pseudowire on an interface that resides on another LC/NP.QoSQoS is handled on the linecard. EARL does not perform QoS operations on L2TPv3 packets.QoS at L2TPv3 Tunnel IngressThe SIP-400 linecard applies QoS to ingress traffic before doing L2TPv3 encapsulation. Given the orderof traffic processing, the SIP-400 linecard can support full-fledged interface/PVC level MQC on Layer2 traffic. QoS on IP tunnel traffic is limited to ToS marking only.The supported QoS-on-ingress Layer 2 frames are as follows.• Classification. Ethernet interfaces: match on vlan, cos, ip dscp, ip precedence. ATM interfaces:match on atm clp• Marking:– Ethernet interfaces: set cos– ATM interfaces: none10