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Hold-queue question...
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- Jan 1, 1970
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hold-queue
To specify the hold-queue limit of an interface, use the hold-queue interface configuration command. Use the no form of this command with the appropriate keyword to restore the default values for an interface.
hold-queue length {in | out}
no hold-queue {in | out}
Syntax Description
length Integer that specifies the maximum number of packets in the queue.
in Specifies the input queue.
out Specifies the output queue.
Default
The default input hold-queue limit is 75 packets. The default output hold-queue limit is 40 packets. These limits prevent a malfunctioning interface from consuming an excessive amount of memory. There is no fixed upper limit to a queue size.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The input hold queue prevents a single interface from flooding the network server with too many input packets. Further input packets are discarded if the interface has too many input packets outstanding in the system.
If priority output queueing is being used, the length of the four output queues is set using the priority-list global configuration command. The hold-queue command cannot be used to set an output hold queue length in this situation.
For slow links, use a small output hold-queue limit. This approach prevents storing packets at a rate that exceeds the transmission capability of the link. For fast links, use a large output hold-queue limit. A fast link may be busy for a short time (and thus require the hold queue), but can empty the output hold queue quickly when capacity returns.
To display the current hold queue setting and the number of packets discarded because of hold queue overflows, use the EXEC command show interfaces.
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Note Increasing the hold queue can have detrimental effects on network routing and response times. For protocols that use seq/ack packets to determine round trip times, do not increase the output queue. Dropping packets instead informs hosts to slow down transmissions to match available bandwidth. This is generally better than having duplicate copies of the same packet within the network (which can happen with large hold queues).
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Example
The following example illustrates how to set a small input queue on a slow serial line:
interface serial 0
hold-queue 30 in
To specify the hold-queue limit of an interface, use the hold-queue interface configuration command. Use the no form of this command with the appropriate keyword to restore the default values for an interface.
hold-queue length {in | out}
no hold-queue {in | out}
Syntax Description
length Integer that specifies the maximum number of packets in the queue.
in Specifies the input queue.
out Specifies the output queue.
Default
The default input hold-queue limit is 75 packets. The default output hold-queue limit is 40 packets. These limits prevent a malfunctioning interface from consuming an excessive amount of memory. There is no fixed upper limit to a queue size.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The input hold queue prevents a single interface from flooding the network server with too many input packets. Further input packets are discarded if the interface has too many input packets outstanding in the system.
If priority output queueing is being used, the length of the four output queues is set using the priority-list global configuration command. The hold-queue command cannot be used to set an output hold queue length in this situation.
For slow links, use a small output hold-queue limit. This approach prevents storing packets at a rate that exceeds the transmission capability of the link. For fast links, use a large output hold-queue limit. A fast link may be busy for a short time (and thus require the hold queue), but can empty the output hold queue quickly when capacity returns.
To display the current hold queue setting and the number of packets discarded because of hold queue overflows, use the EXEC command show interfaces.
--------------------------------------------------------------------------------
Note Increasing the hold queue can have detrimental effects on network routing and response times. For protocols that use seq/ack packets to determine round trip times, do not increase the output queue. Dropping packets instead informs hosts to slow down transmissions to match available bandwidth. This is generally better than having duplicate copies of the same packet within the network (which can happen with large hold queues).
--------------------------------------------------------------------------------
Example
The following example illustrates how to set a small input queue on a slow serial line:
interface serial 0
hold-queue 30 in
- Thread starter
- #3
Thank you for your extensive reply.
I still have a question !
A colleague of mine has made some experiments with the ns simulator and she says that she uses a buffer of 25000 bytes.
How do i configure it in the router ? Not all the packtes have the same size, so how do i set a 25k buffer on the interface ?
thanks for your attention.
I still have a question !
A colleague of mine has made some experiments with the ns simulator and she says that she uses a buffer of 25000 bytes.
How do i configure it in the router ? Not all the packtes have the same size, so how do i set a 25k buffer on the interface ?
thanks for your attention.
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