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Cisco 10000 Series Router Quality of Service Configuration Guide
OL-7433-09
Chapter 15 Oversubscribing Physical and Virtual Links
Frame Relay PVC Oversubscription
Figure 15-1
shows a Frame Relay network that is oversubscribed. In the figure, the Central Site has a
1.544-Mbps Frame Relay circuit. The network has 18 remote sites with 128-kbps Frame Relay circuits.
The aggregate bandwidth is 2.3 Mbps:
128 kbps * 18 sites = 2.3 Mbps
The Central Site is oversubscribed by 50 percent. However, this configuration is valid because:
•
The remote users require only e-mail access and the ability to transfer small files using File Transfer
Protocol (FTP).
•
All of the remote sites are unlikely to try to use all of the available bandwidth at the same time.
•
All of the remote sites are unlikely to simultaneously access the network.
Figure 15-1
Oversubscribed Frame Relay Network
Feature History for Frame Relay PVC Oversubscription
Cisco IOS Release
Description
Required PRE
Release 12.3(7)XI1
The Frame Relay PVC oversubscription feature was
introduced on the PRE2.
PRE2
Release 12.2(28)SB
This feature was integrated in Cisco IOS
Release 12.2(28)SB for the PRE2.
PRE2
126832
1.544 Mbps
Central site
Frame Relay
Network
Aggregate bandwidth
of remotes exceed egress
18 Frame Relay
Access Devices
(FRAD)
128 kbps