Alcatel-Lucent 1643 AMS Applications And Planning Manual page 188

Ethernet Overview
The 10 Mbit/s payload is put into a VC-12–5v, i.e. into a virtual concatenation group
(VCG) consisting of 5 virtually concatenated VC-12s. These VC-12s can travel the
network independently, and do not have to follow the same route. At the endpoint, the
VC-12–5v is reassembled, and the payload is extracted.
Differential delay
Due to the different propagation delay of the VCs a differential delay occurs between
the individual VCs. This differential delay has to be compensated and the individual
VCs have to be re-aligned for access to the contiguous payload area.
The TransLAN
Link Capacity Adjustment Scheme (LCAS)
LCAS is an extension of virtual concatenation that allows dynamic changes in the
number of channels in a connection. In case channels are added or removed by
management actions this will happen without loosing any customer traffic.
LCAS allows a bandwidth service with scalable throughput in normal operation mode.
In case of failure the connection will not be dropped completely but only the affected
channel(s). The remaining channels will continue carrying traffic. LCAS provides
automatic decrease of bandwidth in case of link failure and re-establishment after link
recovery.
....................................................................................................................................................................................................................................
11-12
10 Mbit/s
Ethernet payload
VC-12-5v
0 1 2
VC-12 VC-12 VC-12
VC-12 VC-12 VC-12
0 1 2
VC-12-5v
10 Mbit/s
Ethernet payload
®
re-alignment process covers at least a differential delay of 32 ms.
Alcatel-Lucent - Proprietary
See notice on first page
3 4
VC-12 VC-12
VC-12 VC-12
3 4
Virtual concatenation
365-312-801R7.2
Issue 3, May 2007