Subinterface Mtu; Efps; Layer 2 Vpn On Vlans - Cisco NCS 5500 Series Configuration Manual

Subinterface MTU

Subinterface MTU
The subinterface maximum transmission unit (MTU) is inherited from the physical interface with an additional
four bytes allowed for the 802.1Q VLAN tag. By default subinterface inherits MTU of physical interface if
the MTU is not configured. We can have maximum 3 different MTU for a subinterface per NPU. For
information about Ethernet MTU and Flow Control on Ethernet interfaces, see References for Carrier Ethernet
Model section in L2VPN and Ethernet Services Configuration Guide for Cisco NCS 5000 Series Routers.

EFPs

An Ethernet Flow Point (EFP) is a Metro Ethernet Forum (MEF) term describing abstract router architecture.
An EFP is implemented by an Layer 2 subinterface with a VLAN encapsulation. The term EFP is used
synonymously with an VLAN tagged L2 subinterface. For more information on EFPs, see the Carrier Ethernet
Model chapter in L2VPN and Ethernet Services Configuration Guide for Cisco NCS 5000 Series Routers.

Layer 2 VPN on VLANs

The Layer 2 Virtual Private Network (L2VPN) feature enables Service Providers (SPs) to provide Layer 2
services to geographically disparate customer sites.
The configuration model for configuring VLAN attachment circuits (ACs) is similar to the model used for
configuring basic VLANs, where the user first creates a VLAN subinterface, and then configures that VLAN
in subinterface configuration mode. To create an AC, you need to include the l2transport keyword in the
interface command string to specify that the interface is a Layer 2 interface.
VLAN ACs support these modes of L2VPN operation:
• Basic Dot1Q AC—The AC covers all frames that are received and sent with a specific VLAN tag.
• QinQ AC—The AC covers all frames received and sent with a specific outer VLAN tag and a specific
Each VLAN on a CE-to-PE link can be configured as a separate L2VPN connection (using either VC type 4
or VC type 5).
For more information about Layer 2 VPN on VLANs and their configuration, see the Implementing
Point-to-Point Layer 2 Serviceschapter in L2VPN and Ethernet Services Configuration Guide for Cisco NCS
5000 Series Routers.
Interface and Hardware Component Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release
6.1.x
154
inner VLAN tag. QinQ is an extension to Dot1Q that uses a stack of two tags.
Configuring 802.1Q VLAN Interfaces