Multi Service Edge Device HL950
Administrator’s Guide
EN/LZT 108 5995 R3
Page 40 (159)
June 2003
Example Two: Structured CES without Partial Fill or CAS
Formula:
!
(8000 x N) / 46.875 cells per second
!
(64000 x N x 53) / 46.875 bits per second
where N is the number of 64 kbps timeslots.
In the following example, we configure a structured CES circuit with 8 Nx64 kbps timeslots. Let's
look at the calculated cell rate and bit rate: 8000 x 8 / 46.875 = 1365 cells per second or 64000 x 8 x
53 / 46.875 = 578901 bits per second, which the ATM switch further rounds up to 1366 and 578902
respectively.
Example Three: Structured CES with Partial Fill
Formula:
!
(8000 x N) / K (64000 x N) / K
where K is the number of octets filled per cell, that is the partial cell value.
If we keep the same circuit as Example Two and simply change the partial fill value to 20, note that
the bit rate stays the same, and the cell rate increases significantly from 1366 to 3200. The reason for
this is that partial fill means the CES hardware creates a cell when it accumulates just 20 bytes of
payload (typically voice samples), rather than 47 bytes.
Example Four: Structured CES with Partial Fill and CAS
The formula for structured CES with partial cell fill, N = even, K = the number of AAL1 user octets
filled is:
!
8000 x [Nx49/48] / K64000 x 53 [Nx49/48] / K
where K is the number of octets filled per cell, that is the partial cell value.
