Quantity is how many containers you have. The result is how many tributaries fit, the path, and the leftover line rate. The choices stay in the URL, so you can share them.
Result: standard mapping
How many E1s are in an OC-3?
An OC-3 carries 63 E1s, per Telcordia GR-253.
63
E1s in an OC-3
Working
OC-3 → 3 × OC-1 (STS-1) → 21 × E1
- 3 × OC-1 (STS-1) in each OC-3 Telcordia GR-2533 × OC-1 (STS-1). Channelized OC-3 is 3 STS-1s.
- 21 × E1 in each OC-1 (STS-1) Telcordia GR-253Seven VT groups × three VT2 (E1).
- 3 OC-1s
- 3 × 21 = 63 E1s
Leftover capacity
26.496 Mbit/s of each OC-3 line rate (155.520 Mbit/s) sits outside 63 × 2.048 Mbit/s of E1 line rate (129.024 Mbit/s). That remainder is overhead, fixed stuff or justification. It is not another whole tributary.
By bit rate only
Dividing the line rates gives 75.93, which floors to 75 E1s by bit rate only. The standard mapping is 63. Use the mapping.
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