Huawei quidway s7700 - Page 559

Figure 6-3 Process of tearing down an SH-PW
Loopback1
1.1.1.1/32
Loopback1
2.2.2.2/32
PE1 PE2
mpls l2vc 2.2.2.2 101 mpls l2vc 1.1.1.1 101
VC Deletion
Withdraw
Release
Withdraw
VC Deletion
When PE1 does not forward packets sent from PE2 for a specific cause, that is, PE2 is no longer
a peer of PE2, PE1 sends a Withdraw message to PE2. After receiving the Withdraw message,
PE2 tears down the PW and responds with a Release message. After receiving the Release
message, PE1 releases the label and tears down the PW.
SH-PW and MH-PW
l SH-PW
An SH-PW is set up between two U-PEs. That is, switching labels at PW label layer is not
required, as shown in Figure 6-4.
Figure 6-4 Networking diagram of an SH-PWE3
CE1
CE2
U-PE1
U-PE2
P
PW100
l MH-PW
Quidway S7700 Smart Routing Switch
Configuration Guide - VPN 6 PWE3 Configuration
Issue 01 (2011-07-15) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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