L2Vpn Nonstop Routing; L2Tpv3 Over Ipv6; Overview - Cisco ASR 9000 Series Configuration Manuallines

L2VPN Nonstop Routing

Note Only CEM mode is supported.
Benefits of Circuit Emulation over Packet Switched Network
CEM offers these benefits to the service provider and end-users:
• Saving cost in installing equipment.
• Saving cost in network operations; as leased lines are expensive, limiting their usage to access only mode
• Ensuring low maintenance cost because only the core network needs to be maintained.
• Utilizing the core network resources more efficiently with packet switched network, while keeping
• Providing cheaper services to the end-user.
L2VPN Nonstop Routing
The L2VPN Nonstop Routing (NSR) feature avoids label distribution path (LDP) sessions from flapping on
events such as process failures (crash) and route processor failover (RP FO). NSR on process failure (crash)
is supported by performing RP FO, if you have enabled NSR using NSR process failure switchover.
NSR enables the router (where failure has occurred) to maintain the control plane states without a graceful
restart (GR). NSR, by definition, does not require any protocol extension and typically uses Stateful Switch
Over (SSO) to maintain it's control plane states.

L2TPv3 over IPv6

A L2TPv3 over IPv6 tunnel is a static L2VPN cross-connect that uses Layer 2 Tunneling Protocol version 3
(L2TPv3) over IPv6, with a unique IPv6 source address for each cross-connect. The L2TPv3 over IPv6 tunnels
consists of one L2TPv3 tunnel for each subscriber VLAN. The unique IPv6 address completely identifies the
customer, and the service that is delivered.
Note
L2TPv3 over IPv6 tunnels are supported on the ASR 9000 Enhanced Ethernet line cards by a scale of 15000
crossconnects for each router and line card.

Overview

L2TPv3 defines the L2TP protocol for tunneling Layer 2 payloads over an IP core network using Layer 2
virtual private networks (VPNs). Traffic between two customer network sites is encapsulated in IP packets
carrying L2TP data messages (payload) and sent across an IP network. The backbone routers of the IP network
treat this payload in the same manner as it treats any other IP traffic. Implementing L2TPv3 over IPv6 provides
an opportunity to utilize unique source IPv6 addresses to directly identify Ethernet attachment circuits. In this
case, processing of the L2TPv3 session ID is bypassed; this is because each tunnel has only one associated
L2VPN and Ethernet Services Configuration Guide for Cisco ASR 9000 Series Routers, IOS XR Release 6.3.x
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saves significant costs.
investment in access network intact.
Implementing Point to Point Layer 2 Services