Configuring Drop Timeout Interval for Fragmentation by Forwarding Class

date_range 19-Feb-21

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For LSQ interfaces configured for multiclass MLPPP, you can change the drop timeout interval that the interface waits for fragment resequencing by forwarding class. This feature is mutually exclusive with the no-fragmentation statement configured for a forwarding class.

You can also disable the fragment resequencing function altogether by forwarding class. You do this by setting the drop-timeout interval to 0.

The drop-timeout interval can also be set at the bundle level. When the drop-timeout interval is set to 0 at the bundle level, none of the individual classes forward fragmented packets. Sequencing is ignored also, and packets are forwarded in the order in which they were received. The drop-timeout interval value configured at the bundle level overrides the values configured at the class level.

This example configures a logical unit on an LSQ interface with a fragmentation map setting different drop timeout values for each forwarding class:

Best effort (BE)—The value of 0 means that no resequencing of fragments takes place for BE traffic.
Expedited Forwarding (EF)—The value of 800 ms means that the multiclass MLPPP waits 800 ms for fragment to arrive on the link for EF traffic.
Assured Forwarding (AF)—The absence of the timeout statements means that the default timeouts of 500 ms for links at T1 and higher speeds and 1500 ms for lower speeds are in effect for AF traffic.
Network Control (NC)—The value of 100 ms means that the multiclass MLPPP waits 100 ms for fragment to arrive on the link for NC traffic.

To configure the drop timeout interval:

Define the fragmentation properties for each forwarding class.

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[edit]
user@host# edit class-of-service fragmentation-maps Timeout_Frag_Map
user@host# set forwarding-class BE drop-timeout 0 multilink-class 3 fragment-threshold 128
user@host# set forwarding-class EF drop-timeout 800 multilink-class 2
user@host# set forwarding-class NC drop--timeout 100 multilink-class 0 fragment-threshold 512
user@host# set forwarding-class AF multilink-class 1 fragment-threshold 256

Apply the fragmentation map to the logical interface.

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[edit class-of-service]
user@host# set interfaces lsq-1/0/0 unit 1 fragmentation-map Timeout_Frag_Map

Verify the configuration.

Verify the Configuration of the Fragmentation Map Properties

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[edit class-of-service fragmentation-maps Timeout_Frag_Map]
user@host# show 
forwarding-class {
    BE {
        fragment-threshold 128;
        multilink-class 3;
        drop-timeout 0;  # no resequencing for this forwarding class
    }
    EF {
        multilink-class 2;
        drop-timeout 800;
    }
    NC {
        fragment-threshold 512;
        multilink-class 0;
        drop-timeout 100;
    }
    AF {
        fragment-threshold 256;  # Default timeout in effect for this class
        multilink-class 1;
    }
}

Verify the Fragmentation Map is Applied to the Logical Interface

content_copy zoom_out_map
[edit class-of-service]
user@host# show 
interfaces {
 lsq-1/0/0 {
        unit 1 {
            fragmentation-map Tineout_frag_Map;
        }
    }

Save the configuration.
```
[edit]
user@host# commit
```

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Class of Service User Guide (Routers and EX9200 Switches)

Configuring Drop Timeout Interval for Fragmentation by Forwarding Class

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Class of Service User Guide (Routers and EX9200 Switches)

Configuring Drop Timeout Interval for Fragmentation by Forwarding Class

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