Figure 5-4 Networking Of Sh-Pwe3; Figure 5-5 Networking Of Mh-Pwe3 - Huawei Quidway S9300 Configuration Manual

5 PWE3 Configuration
When PE1 does not forward packets sent from PE2 for a certain reason, for example, PE2 is no
longer specified as the peer, PE1 sends a Withdraw message to PE2. After receiving the
Withdraw message, PE2 tears down the PW tunnel and returns a Release message to PE1. After
receiving the Release message, PE1 releases the label and tears down the PW tunnel.
SH-PW and MH-PW
l
l
5-6
SH-PW
The SH-PW (single-hop PW) is a PW set up between two U-PEs. That is, switching labels
at PW label layer is not required, as shown in

Figure 5-4 Networking of SH-PWE3

PE1
CE1
MH-PW
The MH-PW (multi-hop PW) is a set of two or more contiguous PW segments between
two U-PEs, as shown in
same as that in SH-PW except that the MH-PW requires exchange of PW labels on the
switching PE (S-PE).

Figure 5-5 Networking of MH-PWE3

U-PE1
PW100
CE1
To carry out MH-PWs, the S-PE needs to connect the SH-PWs at both the endpoints of the
PW and switch the labels at the PW level on the S-PE. PWs can be switched in the following
modes:
Dynamic-and-dynamic switch: The PWs on the two sides of the S-PE are set up through
–
signaling. The remote labels are sent from the two neighboring endpoints (U-PE or S-
PE) to this S-PE using signaling.
Static-and-static switch: The PWs on the two sides of the S-PE are configured manually.
–
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Figure
P
PE2
PW100
Figure 5-5. The forwarding mechanism of U-PE in MH-PW is the
S-PE P
PW200
Quidway S9300 Terabit Routing Switch
Configuration Guide - VPN
5-4.
CE2
U-PE2
CE2
Issue 03 (2009-08-20)