A Case of CBQ EF Reserved-Bandwidth Can Not Larger Than 48 K

Publication Date:  2012-07-27 Views:  244 Downloads:  0
Issue Description
This case is about the CBQ interconnection between Quidway R3680E (VRP1.74-0101) and Cisco router. When configed the CBQ EF reserved-bandwidth as 2M on the serial port of Quidway R3680E, system prompted that the available bandwidth was only 48K. But there wasn't any config about the 48K limitation.
Alarm Information
System prompted that the available bandwidth was only 48K.
Handling Process
1. Since R3680E was DTE site, there wasn't any configuration about bandwidth limitation. Checking the configuration of Cisco router (DCE site), the bandwidth limitation was 2M. 2. Displayed qos cbq interface on R3680E, the parameters of 'reserved-bandwidth' and 'max-bandwidth' were 48K and 64K. This is the reason of this problem. 3. Tried to use commands of 'qos max-bandwidth' and 'qos reserved-bandwidth' to change these two parameters to 2M, then configed the CBQ EF reserved-bandwidth to 2M. Everything was OK.
Root Cause
Because system prompted that the available bandwidth was only 48K and there wasn't any config about this limitation, this problem maybe because of serial port negociation or some default parameters of R3680E.

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