viiiConfiguring L2TP ········································································· 250About L2TP ·························································································································· 250Typical L2TP networking ··································································································· 250L2TP message types and encapsulation structure ·································································· 250L2TP tunnel and session ··································································································· 251L2TP tunneling modes and tunnel establishment process ························································ 251L2TP features ················································································································· 254L2TP-based EAD ············································································································ 256Protocols and standards ··································································································· 256Restrictions: Hardware compatibility with L2TP ············································································ 256Restrictions and guidelines: L2TP configuration ············································································ 256L2TP tasks at a glance ············································································································ 257Configuring basic L2TP capabilities ··························································································· 258Configuring an LAC ················································································································ 258Configuring an LAC to initiate tunneling requests for a user ······················································ 258Specifying LNS IP addresses ····························································································· 259Configuring the source IP address of L2TP tunnel packets ······················································· 259Configuring each L2TP user to use an L2TP tunnel exclusively ················································· 259Enabling transferring AVP data in hidden mode ····································································· 260Configuring AAA authentication on an LAC ··········································································· 260Configuring an LAC to automatically establish an L2TP tunnel ·················································· 260Configuring an LNS ················································································································ 261Creating a VT interface ····································································································· 262Configuring an LNS to accept L2TP tunneling requests from an LAC ·········································· 262Configuring user authentication on an LNS ··········································································· 262Configuring AAA authentication on an LNS ··········································································· 264Setting the maximum number of ICRQ packets that the LNS can process per second ···················· 264Configuring optional L2TP parameters ························································································ 264Configuring L2TP tunnel authentication ················································································ 264Setting the Hello interval ··································································································· 265Setting the DSCP value of L2TP packets ·············································································· 265Setting the TSA ID of the LTS ···························································································· 265Enabling L2TP-based EAD ······································································································ 266Configuring IMSI/SN binding authentication on the LNS ································································· 266Display and maintenance commands for L2TP ············································································· 267L2TP configuration examples ··································································································· 267Example: Configuring a NAS-initiated L2TP tunnel ································································· 267Example: Configuring a client-initiated L2TP tunnel ································································ 270Example: Configuring an LAC-auto-initiated L2TP tunnel ························································· 271Troubleshooting L2TP ············································································································· 273Failure to access the private network ··················································································· 273Data transmission failure ··································································································· 274L2TP user offline ············································································································· 274Configuring PPPoE ······································································· 275About PPPoE ························································································································ 275PPPoE network structure ········································································································· 275Router-initiated network structure ······················································································· 275Host-initiated network structure ·························································································· 276Protocols and standards ·········································································································· 276Restrictions: Hardware compatibility with IPoE ············································································· 276Restrictions and guidelines: PPPoE configuration ········································································· 276Configuring the PPPoE server ·································································································· 277PPPoE server tasks at a glance ························································································· 277Configuring a PPPoE session ···························································································· 277Setting the maximum number of PPPoE sessions ·································································· 278Limiting the PPPoE access rate ·························································································· 278Configuring the NAS-Port-ID attribute ·················································································· 279Enabling PPPoE users to come online despite the PPPoE-NAT444 collaboration failure ················ 280Setting the maximum number of PADI packets that the device can receive per second ·················· 281Configuring PPPoE user blocking ······················································································· 281