Command:

max-reserved-bandwidth


Mode:

Router(config-if)#


Syntax:

max-reserved-bandwidth percent
no max-reserved-bandwidth

 

Syntax Description:

percent Percent of interface bandwidth allocated for RSVP, CBWFQ, LLQ, IP RTP Priority, Frame Relay IP RTP Priority, and Frame Relay PIPQ.

 

Command Description:

To change the percent of interface bandwidth allocated for Resource Reservation Protocol (RSVP), class-based weighted fair queueing (CBWFQ), low latency queueing (LLQ), IP RTP Priority, Frame Relay IP RTP Priority, and Frame Relay PVC Interface Priority Queueing (PIPQ), use the max-reserved-bandwidth interface configuration command. To restore the default value, use the no form of this command.

The default is 75 percent.

The sum of all bandwidth allocation on an interface should not exceed 75 percent of the available bandwidth on an interface. The remaining 25 percent of bandwidth is used for overhead, including Layer 2 overhead, control traffic, and best-effort traffic.

If you need to allocate more than 75 percent for RSVP, CBWFQ, LLQ, IP RTP Priority, Frame Relay IP RTP Priority, and Frame Relay PIPQ, you can use the max-reserved-bandwidth command. The percent argument specifies the maximum percentage of the total interface bandwidth that can be used.

If you do use the max-reserved-bandwidth command, make sure that not too much bandwidth is taken away from best-effort and control traffic.

The max-reserved-bandwidth command is intended for use on main interfaces only; it has no effect on virtual circuits (VCs) or ATM permanent virtual circuits (PVCs).


Example:

In the following example, the policy map called policy1 is configured for three classes with a total of 8 Mbps configured bandwidth, as shown in the output from the show policy-map command:

Router#show policy-map policy1
Policy Map policy1
Weighted Fair Queueing
Class class1
Bandwidth 2500 (kbps) Max Threshold 64 (packets)
Class class2
Bandwidth 2500 (kbps) Max Threshold 64 (packets)
Class class3
Bandwidth 3000 (kbps) Max Threshold 64 (packets)

When you enter the service-policy command in an attempt to attach the policy map on a 10-Mbps Ethernet interface, an error message such as the following is produced:

I/f Ethernet1/1 class class3 requested bandwidth 3000 (kbps) Available only 2500 (kbps)

The error message is produced because the default maximum configurable bandwidth is 75 percent of the available interface bandwidth, which in this example is 7.5 Mbps. To change the maximum configurable bandwidth to 80 percent, use the max-reserved-bandwidth command in interface configuration mode, as follows:

max-reserved-bandwidth 80
service output policy1
end

To verify that the policy map was attached, enter the show policy-map interface command:

Router#show policy-map interface e1/1
Ethernet1/1 output :policy1
Weighted Fair Queueing
Class class1
Output Queue:Conversation 265
Bandwidth 2500 (kbps) Packets Matched 0 Max Threshold 64 (packets)
(discards/tail drops) 0/0
Class class2
Output Queue:Conversation 266
Bandwidth 2500 (kbps) Packets Matched 0 Max Threshold 64 (packets)
(discards/tail drops) 0/0
Class class3
Output Queue:Conversation 267
Bandwidth 3000 (kbps) Packets Matched 0 Max Threshold 64 (packets)
(discards/tail drops) 0/0

Virtual Template Configuration Example

The following example configures a strict priority queue in a virtual template configuration with CBWFQ. The max-reserved-bandwidth command changes the maximum bandwidth allocated between CBWFQ and IP RTP Priority from the default (75 percent) to 80 percent.

multilink virtual-template 1
interface virtual-template 1
 ip address 172.16.1.1 255.255.255.0
 no ip directed-broadcast
 ip rtp priority 16384 16383 25
service-policy output policy1
ppp multilink
ppp multilink fragment-delay 20
ppp multilink interleave
max-reserved-bandwidth 80
end
interface Serial0/1
bandwidth 64
ip address 10.1.1.2 255.255.255.0
no ip directed-broadcast
encapsulation ppp
ppp multilink
end


Misconceptions:

To make the virtual access interface function properly, do not configure the bandwidth command on the virtual template. Configure it on the actual interface, as shown in the example.


Related Commands:

None

� Cisco Systems, Inc. 2001, 2002, 2003
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