Circuit Bonding Technology
Circuit bonding solves all of the major problems (just noted) that are associated with
the transmission of Ethernet service in the MAN environment. Ethernet frames are
transported over the network using the ITU standard GFP/VC/LCAS scheme.
In many instances, it is desirable to concatenate or ???bond??? many different links??”
either physical or virtual??”into a single virtual link or pipe. Doing so offers customers
or service providers several advantages, including increased efficiency of the physical
transport medium and potentially simplified management of one link versus complicated
management of several. Let??™s examine the basic theory and standards utilized
for circuit bonding.
SONET Multiplexing: Virtual Concatenation, LCAS, and Generic Framing Protocol A SONET
multiplexer combines STS-1s by interleaving bytes to create a ???higher-order??? STS-N. The
protocol is designed to scale by increasing the size of the multiplexed channel. Figure 10.1
Figure 10.1 SONET multiplexing
STS-1
STS-1
STS-1
3:1
STS-1
STS-1
STS-1
3:1
STS-1
STS-1
STS-1
3:1
STS-1
STS-1
STS-1
3:1
16:1
STS-48
STS-3
STS-3
STS-3
STS-3
TDM: Circuit Bonding 269
is a block diagram showing a possible method to construct an STS-48 from 48 STS-1s.
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