EXFO IQS-8100 Series Transport Blazer for IQS-600 - Manual (Page 678)

Glossary
664 IQS-8100 Series Transport Blazer
Next-Gen - Virtual Concatenation (VCAT)
High-Order Virtual Concatenation (HO VCAT)
HO VCAT provides bandwidth for links that require speeds greater than
51.84 Mb/s, but do not lend themselves to one of the standard contiguous
concatenation bandwidth configurations. HO VCAT is realized under
SONET and SDH by the PTE, which combines either multiple STS-1/STS-3c
SPEs (for SONET) or VC-3/VC-4s (for SDH), therefore making it ideally
suited for transport of 100M, Gigabit Ethernet, and Fibre Channel rates.
HO VCAT rates are designated by STS-m-nv or VC-m-nv, where the nv
indicates a multiple n of the STS-m/VC-m base rate.
³
HO VCAT Frame Structure
As mentioned, a HO VCG super-container can be formed by using
STS-1 or STS-3c in SONET and VC-3 (AU-3) or VC-4 (AU-4) in SDH. This
means that a SONET virtually concatenated payload STS-1/3c-Xv or an
SDH VC-3/4-Xv can transport X*48384/149760 kb/s, as shown
respectively in figure STS-1/3c-Xv VCG on page 665 and figure
VC-3/4-Xv VCG on page 665, assuming the stuff bytes remain
untouched.
In either case, the value of X can be between 1 and 256. Each SONET
SPE or SDH VC used to create a VC contains its individual path
overhead (POH). Among these bytes is the H4 byte, used to specify the
virtual concatenation multiframe indicator (MFI) and sequence
indicator (SQ).