Manual

Layer 2 Tunnel Protocol Version 3

Restrictions for Layer 2 Tunnel Protocol Version 3

Cisco IOS Releases 12.0(29)S and 12.2(25)S

• Point-to-multipoint and multipoint-to-point configurations are not supported. There is a 1:1

relationship between an attachment circuit and an L2TPv3 session.

ATM VP Mode Single Cell Relay over L2TPv3 Restrictions

• The ATM VP Mode Single Cell Relay over L2TPv3 feature is supported only on the Cisco 7200 and

Cisco 7500 series routers with ATM Deluxe PA-A3 interfaces.

• Once the ATM VP Mode Single Cell Relay feature is configured for a virtual path connection (VPC),

no other permanent virtual circuits (PVCs) will be allowed for the same virtual path identifier (VPI).

ATM AAL5 SDU over L2TPv3 and Single Cell Relay VC Mode over L2TPv3

Restrictions

• The ATM AAL5 OAM Emulation over L2TPv3 feature and the ATM Single Cell Relay VC Mode

over L2TPv3 feature are supported only on the Cisco 7200 and Cisco 7500 series routers with ATM

Deluxe PA-A3 interfaces.

• Sequencing is supported only for ATM adaptation layer 5 (AAL5) service data unit (SDU) frames

or ATM cell relay packets. Sequencing of Operation, Administration, and Maintenance (OAM) cells

is not supported.

• Sequencing is supported in CEF mode. If sequencing is enabled with dCEF, all L2TP packets that

require sequence number processing will be sent to the RSP module.

• L2TPv3 manual mode configuration does not support ATM alarm signaling over the pseudowire.

• The Cisco 7200 and the Cisco 7500 ATM driver cannot forward Resource Management (RM) OAM

cells over the packet-switched network (PSN) for available bit rate (ABR) ToS. The RM cells will

be locally terminated.

ATM Port Mode Cell Relay over L2TPv3 Restrictions

• Port mode and virtual path (VP) or VC mode cell relay are mutually exclusive. Once the ATM

interface is configured for cell relay, no permanent virtual path (PVP) or PVC commands will be

allowed on that interface.

• ATM port mode cell relay is supported only on the PA-A3-T3, PA-A3-E3, and PA-A3-OC3 ATM

port adapters.

• ATM port mode cell relay is not supported on the PA-A3-8T1IMA and PA-A3-8E1IMA port

adapters.

ATM Cell Packing over L2TPv3 Restrictions

• The ATM Cell Packing over L2TPv3 feature is supported only on PA-A3 ATM interfaces on

Cisco 7200 and Cisco 7500 routers. Cell packing cannot be configured on other platforms or

interface cards.

• A minimum of 2 and a maximum of 28 ATM cells can be packed into an L2TPv3 data packet.