Vll Diagnostics; Vccv Ping - Alcatel-Lucent 7750 SR OS Service Manual

OAM Overview

VLL Diagnostics

VCCV Ping

VCCV ping is used to check connectivity of a VLL in-band. It checks that the destination (target)
PE is the egress for the Layer 2 FEC. It provides a cross-check between the data plane and the
control plane. It is in-band, meaning that the VCCV ping message is sent using the same
encapsulation and along the same path as user packets in that VLL. This is equivalent to the LSP
ping for a VLL service. VCCV ping reuses an LSP ping message format and can be used to test a
VLL configured over an MPLS and GRE SDP.
VCCV-Ping Application
VCCV creates an IP control channel within the pseudowire between PE1 and PE2. PE2 should be
able to distinguish, on the receive side, VCCV control messages from user packets on that VLL.
The 7750 SR uses the router alert label immediately above the VC label to identify the VCCV-ping
message. This method has a drawback that if ECMP is applied to the outer LSP label, such as the
transport label, the VCCV message will not follow the same path as the user packets.
When sending the label mapping message for the VLL, PE1 and PE2 include an optional VCCV
TLV in the PW FEC interface parameter field. The TLV indicates that the control channel will
make use of the router alert label method. An example of VCCV ping is shown in
CE 1 [64.47.30.1/30]
FR SAP
1/1/1:100
Page 1374
VCCVE cho
Request
7750 SR
FRPW
IP/MPLS
PE 1
Figure 1: VCCV-Ping Application
VCCVE cho
Reply
7750 SR
FR SAP
1/1/1:200
PE 2
7750 SR OS Services Guide
Figure 71.
CE 2 [64.47.30.2/30]
IPIPE_010