Manual

Layer 2 Tunnel Protocol Version 3
Restrictions for Layer 2 Tunnel Protocol Version 3
8
Cisco IOS Releases 12.0(29)S and 12.2(25)S
Backward explicit congestion notification (BECN) and forward explicit congestion notification
(FECN) configuration are not supported.
The Type of Service (ToS) byte must be configured in IP headers of tunneled Frame Relay
packets when you configure the L2TPv3 pseudowire (see Configuring the L2TPv3 Pseudowire,
page 34).
All standard restrictions for configuring QoS on Cisco 12000 series line cards apply to
configuring QoS for L2TPv3 on Cisco 12000 series 2-port Ch OC-3/STM-1 (DS1/E1) or 6-port
Ch T3 line cards.
On the ingress side of a Cisco 12000 series Frame Relay interface:
• Weighted random early detection (WRED) and modified deficit round robin (MDRR)
configurations are not supported.
On the egress side of a Cisco 12000 series Frame Relay interface:
• Modified Deficit Round Robin (MDRR) is the only queuing strategy supported.
• Weighted Random Early Detection (WRED) is the only packet drop strategy supported.
• MDRR is supported only in the following modes:
With both a low latency (priority) queue and class-default queue configured. (The low latency
queue is only supported in combination with the class-default queue, and cannot be configured
with normal distributed round robin (DRR) queues.)
Without a low latency queue configured. (In this case, only 6 queues are supported, including
the class-default queue.)
• Egress queuing is determined according to the IP Precedence value(s) configured for classes of
L2TPv3 Frame Relay traffic using the match ip precedence command, instead of on a
per-DLCI basis.
• The configuration of an L2TPv3 session on a Multilink Frame Relay (MLFR) bundle interface is
supported only on Cisco 12000 series Two-Port Channelized OC-3/STM-1 (DS1/E1) and Six-Port
Channelized T3 (T1) line cards. (For more information, see Binding L2TPv3 Sessions to Multilink
Frame Relay Interfaces, page 21.)
• Frame Relay policing is nondistributed on the Cisco 7500 series. By configuring Frame Relay
policing, you cause traffic on the affected PVCs to be sent to the RSP for processing.
• Frame Relay support is for 10-bit DLCI addresses. Frame Relay Extended Addressing is not
supported.
• Multipoint DLCI is not supported.
• The keepalive will automatically be disabled on interfaces that have an Xconnect applied to them,
except for Frame Relay encapsulation, which is a requirement for LMI.
• Static L2TPv3 sessions will not support Frame Relay LMI interworking.
VLAN-Specific Restrictions
• A PE router is responsible only for static VLAN membership entries that are manually configured
on the router. Dynamic VLAN membership entries, entry aging, and membership discovery are not
supported.
• Implicit tagging for VLAN membership operating on the other layers (such as at Layer 2,
membership by MAC address or protocol type, at Layer 3, or membership by IP subnet) is not
supported.