OAM Overview
Page 1376 7750 SR OS Services Guide
Pseudowire switching is a method to scale a large network of VLL or VPLS services by removing
the need for a full mesh of T-LDP sessions between the 7x50 PE nodes as the number of these
nodes grows over time. In the network displayed in Figure 72, a terminator PE (T-PE) is where the
pseudowire originates and terminates. The switching PE (S-PE) is the node that performs
switching by cross-connecting two spoke SDPs.
VCCV ping supports the following OAM functions:
• VCCV ping to a destination PE. A VLL FEC ping is a message sent by T-PE1 to test the
FEC at T-PE2. The operation at T-PE1 and T-PE2 is the same as in the case of a single-
segment pseudowire in Figure 72.
An alternative method, based on T-PE1 including a new multi-segment pseudowire
control word which gets processed by S-PE1, is described in draft-hart-pwe3-segmented-
pw-vccv-00.txt, VCCV Extensions for Segmented Pseudo-Wire.
• Use of the OAM control word (Figure 73).
Figure 3: OAM Control Word Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1| FmtID | Reserved | Channel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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