Huawei quidway s7700, Configuration Manual

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l Attachment Circuit (AC) : AC is an independent link or circuit that connects CE and PE.
The AC interface may be a physical interface or a logical interface. The AC attributes
include the encapsulation type, MTU and interface parameters of specified link type.
l Virtual Circuit (VC) : It refers to a kind of logical connection between two PEs.
l Tunnel (Network Tunnel) : It transmits the user data transparently.
Through the label stack, VLL can realize the transparent transmission of user datagram in an
MPLS network.
l
Outer label: The label, which is also called tunnel label, is used in transferring packets from
one PE to another.
l Inner label: The label, which is also called VC label in VLL, is used to identify different
links between VPNs. The PE on the receiver side transfers packets to the corresponding
CE according to the VC label.
Figure 5-2 shows the packet label change in the forwarding process.
Figure 5-2 VLL label processing
P CE 1 CE 2 PE 1 PE 2
L2PDU L2PDU L2PDU T' V
L2PDU
T V
Figure 5-2 shows the Layer 2 Protocol Data Unit (PDU) that is the link layer packet.
Here, T represents Tunnel label; V represents VC label; T' indicates that the outer label is
substituted in the forwarding process.
5.2 VLL Features Supported by the S7700
VLL can be implemented in four modes, namely, Circuit Cross Connect (CCC), Switched
Virtual Circuit (SVC), Kompella, and Martini. VLL also supports inter-Autonomous System
(inter-AS) applications.
CCC VLL
The Circuit Cross Connect (CCC) implements the VLL by static configuration.
Unlike common VLL, the CCC adopts one label to transfer user data, so it uses the LSP
exclusively. These LSPs can only be used to transfer the data of this CCC link, and cannot be
used in other VLL links, BGP/MPLS VPN, or used to transfer common IP packets.
The two types of CCC connection are as follows:
l Local connection: refers to the connection between two local CEs. The two CEs are
connected to the same PE. Similar to a layer 2 switch, PE can directly transport packets
without configuring static LSP.
l Remote connection: refers to the connection between local CE and remote CE. The two
CEs are on different PEs. In this case, static LSP configuration is needed to transfer packets
Quidway S7700 Smart Routing Switch
Configuration Guide - VPN
5 VLL Configuration
Issue 01 (2011-07-15) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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