Your customer would like to investigate converging voice and data on their existing T1 Frame Relay WAN link betweenNew YorkandAtlanta. The following applications are consuming no more bandwidth than what is in the list on this segment of the network.
T1 link 1536 Kbps
e-mail 75 Kbps
Internet 200 Kbps
Oracle 500 Kbps
FTP 250 Kbps
Total 1025 Kbps
The customer has allocated 25% of the WAN link for routing updated and other overhead. Assuming 6 bytes overhead for Frame Relay, nocRTPand using the G.729 codec, how many calls could be placed on this link?
A.
2 calls
B.
3 calls
C.
4 calls
D.
5 calls
E.
6 calls
Explanation:
Based upon a total bandwidth of 1536 Kbps and 1025 Kbps being used by other applications you can only have 4 calls not 5. The reason is that of the 1536 Kbps of bandwidth only 75% of it is available (or 1152 Kbps). 1152 minus 1025 leaves just 127 Kbps available for voice traffic. Assuming that you are using FRF.12, G.729 (stated in this scenario), and nocRTP(also stated in this scenario) then you will need approximately 28.14 Kbps per call with 5% overhead included (26.8 Kbps without overhead). 26.8 x 5 = 134 Kbps and 28.14 x 5 = 140.7 Kbps.
Both exceed the 127 Kbps available for voice. To calculate the required bandwidth reference the “Voice Codec Bandwidth Calculator” available on Cisco’s web site (requires a CCO sign-on to access the calculator).