Introduction To Vll - Huawei Quidway S9300 Configuration Manual

Quidway S9300 Terabit Routing Switch
Configuration Guide - VPN

4.1 Introduction to VLL

This section describes the principles of VLL.
Traditional VPNs are based on Asynchronous Transfer Mode (ATM) or Frame Relay (FR) where
different VPNs can share the network structure of carriers. The disadvantages of traditional
VPNs are as follows:
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To avoid the preceding disadvantages, new solutions are introduced. Virtual Leased Line (VLL)
based on the MPLS L2VPN is one of the solutions.
The S9300 provides L2VPN services based on the MPLS network to enable carriers to establish
L2VPNs on different media including VLAN and Ethernet. In addition, the MPLS network can
still provide traditional services, such as IP services, MPLS L3VPN services, traffic engineering,
and QoS.
VLL transparently transmits Layer 2 data of users on the MPLS network. For the users, the
MPLS network acts as a Layer 2 switched network through which Layer 2 connections can be
set up between nodes.
Compared with BGP/MPLS VPN, VLL has the following advantages:
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Figure 4-1
Issue 03 (2009-08-20)
Traditional VPNs are dependent on media such as ATM or FR. To provide VPN services
based on ATM, carriers must set up ATM networks covering all service areas. Similarly,
to provide VPN services based on FR, carriers must set up FR networks covering all service
areas. This leads to extra expenditure of carriers.
The deployment of traditional VPNs is complex. When adding a site to an existing VPN,
you must modify the configurations on all the edge nodes accessing this VPN.
NOTE
VLL in this chapter refers to VLL based on MPLS L2VPN, unless otherwise specified.
NOTE
On the MPLS L2VPN, the concepts and principles of the CE, Provider Edge (PE), and Provider (P) are
similar to those in the Border Gateway Protocol (BGP)/MPLS L3VPN.
High scalability: VLL establishes Layer 2 connections only. It does not import or manage
routing information of users. It greatly reduces the load on PEs and the SP network. This
enables the carrier to support more VPN services and more users.
Reliability and guaranteed security of VPN routing information: VLL cannot obtain or
process VPN routing information because the routing information is not imported. This
ensures the security of VPN routes.
Support for network layer protocols: IP, IPX, and SNA.
shows the model of a VLL.
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4 VLL Configuration
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