Configuring graceful degradation – Cisco 3825 User Manual
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Cisco 3825 Mobile Wireless Edge Router Software Configuration Guide
OL-15667-03
Chapter 4 Configuring the Cisco 3825 Mobile Wireless Edge Router in a RAN-O Solution with the Command-Line
Configuration Sequence
Step 2
To configure the jitter buffer, enter the following command including the value of the jitter buffer.
Router(config-if)# gsm-abis jitter value ms
Where ms is the value range in milliseconds of the jitter buffer. The default is 4 ms.
For example, the following command configures the gsm-abis jitter buffer to 10 ms:
Router(config-if)# gsm-abis jitter 10
Step 3
To configure the tunable retransmission timer, enter the following command including the value in
milliseconds to retransmit.
Router(config-if)# gsm-abis retransmit value
Where value is the sample delay which is a value range of the retransmission of 100 ms to 5100 ms in
20 ms intervals. For example, if the value is 5, then the amount of time in ms would be calculated as 5
times 20 ms or a total of 100 ms as the retransmit time.
For example, the following command configures the gsm-abis retransmit timer to a value of 5 or
100 ms:
Router(config-if)# gsm-abis retransmit 5
Configuring Graceful Degradation
A local Cisco 3825 router detects congestion on the backhaul by measuring its transmit jitter buffer level.
If the transmit jitter buffer shrinks, it means that the backhaul packets are not arriving fast enough to fill
the transmit jitter buffer indicating congestion. You should set the congestion abatement detection level
at which a remote router will stop suppressing these timeslots.
Use the following instructions to configure graceful degradation on the Cisco 3825 router by entering
the following Cisco IOS commands at the router prompt.
You might also need to enter other configuration commands, depending on the requirements for your
system configuration and the protocols you plan to route on the interface.
Note
In the following procedure, press the Return key after each step unless otherwise noted. At any time,
you can exit the privileged level and return to the user level by entering disable at the
Router#
prompt.
To configure graceful degradation, follow these steps while in the global configuration mode:
Step 1
Perform Steps 1 through 10 as described in the previous procedure (see the
).
Step 2
To set the congestion detection algorithm to monitor the transmit jitter buffer so as to send the congestion
indicator signals to the remote when the congestion is detected, enter the following command.
Router(config-if)# gsm-abis congestion enable
Step 3
To set the congestion abate detection level, enter the following command.
Router(config-if)# gsm-abis congestion abate ms
Where ms is the value of the congestion abate in milliseconds.