Manual

Layer 2 Tunnel Protocol Version 3
Restrictions for Layer 2 Tunnel Protocol Version 3
7
Cisco IOS Releases 12.0(29)S and 12.2(25)S
• On Engine 2 line cards, the input Frame Relay permanent virtual circuit (PVC) counters will not be
updated.
• The 8-port Fast Ethernet line card should not be connected to a hub or switch when L2TPv3 is
configured on the ingress side of one or more of its ports, or duplicate packets will be generated,
causing the router to be flooded with packets. This restriction results from the requirement that
CAM filtering is disabled when L2TPv3 is used.
• On the 3-port Gigabyte Ethernet line card, performance degradation can occur if IP packets coming
from a port are sent to the slow path for forwarding. This performance degradation will occur if both
the following conditions are met:
– The port has at least one 802.1q subinterface that is in an L2TPv3 session.
– The IP packet comes from the port interface itself (not 802.1q encapsulated) or from an 802.1q
subinterface that is under the port interface but has no L2TPv3 session bound to it.
• On the 1-port OC-48c/STM-16c POS/SDH line card, the maximum performance of 2.5 million pps
is achieved only if you use transmit buffer management (TBM) ASIC ID 60F1. Other ASIC ID
versions can cause the performance to be reduced by half. To determine the ASIC value of the line
card, use the execute-on slot slot-number show controller frfab bma reg | include asic command,
where slot-number is the slot number of the server card.
• The optics of the 1-port OC-48c/STM-16c POS/SDH line card should be covered due to possible
interference or noise causing cyclic redundancy check (CRC) errors on the line card. These errors
are caused by a framer problem in the line card.
Frame Relay-Specific Restrictions
• Frame Relay per-DLCI forwarding and port-to-port trunking are mutually exclusive. L2TPv3 does
not support the use of both on the same interface at the same time.
• The xconnect command is not supported on Frame Relay interfaces directly. For Frame Relay, the
Xconnect is applied under the connect command specifying the DLCI to be used.
• Changing the encapsulation type on any interface removes any existing xconnect command applied
to that interface.
• To use DCE or a Network-to-Network Interface (NNI) on a Frame Relay port, you must configure
the frame-relay switching command.
• Quality of Service (QoS) policies configured with the Modular Quality of Service command-line
interface (MQC) are supported by L2TPv3 on Frame Relay interfaces as follows:
– On the Cisco 7500 series with distributed CEF (dCEF), in a QoS policy applied to a Frame
Relay interface configured for L2TPv3, only the MQC commands match fr-dlci in class-map
configuration mode and bandwidth in policy-map configuration mode are supported. (See
Configuring QoS for L2TPv3 on the Cisco 7500 Series Example, page 58.)
– On the Cisco 12000 series, a QoS policy is supported by L2TPv3 only on the Frame Relay
interfaces of a Two-Port Channelized OC-3/STM-1 (DS1/E1) and Six-Port Channelized T3 (T1)
line card. (See Configuring QoS for L2TPv3 on the Cisco 12000 Series Example, page 59.)
The police command is supported as follows:
• Only the transmit keyword is supported with the conform-action action parameter.
• Only the set-frde-transmit value is supported with the exceed-action action parameter.
• Only the drop value is supported with the violate-action action parameter.