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Configuring IQE PIC ToS Translation

On the IQE PICs, the behavior aggregate (BA) translation tables are included for every logical interface (unit) protocol family configured on the logical interface. The proper default translation table is active even if you do not include any explicit translation tables. You can display the current translation table values with the show class-of-service classifiers command.

On the M320 and T-series, M120, and M40e routing platforms with IQE PICs, you can replace the ToS bit value on the incoming packet header on a logical interface with a user-defined value. The new ToS value is used for all class-of-service processing and is applied before any other class-of-service or firewall treatment of the packet. The IQE PIC uses the translation-table statement to determine the new ToS bit values.

You can configure a physical interface (port) or logical interface (unit) with up to three translation tables. For example, you can configure a port or unit with BA classification for IPv4 DSCP, IPv6 DSCP, and MPLS EXP. The number of frame relay DLCIs (units) that you can configure on each PIC will vary based on the number and type of BA classification tables configured on the interfaces.

To configure ToS translation on the IQE PIC, include the following statements at the [edit class-of-service] hierarchy level:




translation-tables {


(to-dscp-from-dscp | to-dscp-ipv4-from-dscp-ipv6 | to-inet-precedence-from-inet-precedence
| to-exp-from-exp) trans-table-name {
to-code-point value from-code-point value(s);
to-code-point value from-code-point
*;
}


}

The from-code-point statement establishes the values to match on the incoming packets. The default option is used to match all values not explicitly listed, and, as a single entry in the translation table, to mark all incoming packets on an interface the same way. The to-code-point statement establishes the target values for the translation. If an incoming packet header ToS bit configuration is not covered by the translation table list and a * option is not specified, the ToS bits in the incoming packet header are left unchanged.

You can define many translation tables, as long as they have distinct names. You apply a translation table to a logical interface at the [edit class-of-service interfaces] hierarchy level. Translation tables always translate “like to like.” For example, a translation table applied to MPLS traffic can only translate from received EXP bit values to new EXP bit values. That is, translation tables cannot translate (for instance) from DSCP bits to INET precedence code points.

On the IQE PIC, incoming ToS bit translation is subject to the following rules:

Locally generated traffic is not subject to translation.
The to-dscp-from-dscp translation table type is not supported if an Internet precedence classifier is configured.
The to-inet-precedence-from-inet-precedence translation table type is not supported if a DSCP classifier is configured.
The to-dscp-from-dscp and to-inet-precedence-from-inet-precendence translation table types cannot be configured on the same unit.
The to-dscp-from-dscp and to-inet-precedence-from-inet-precendence translation table types are supported for IPv4 packets.
Only the to-dscp-ipv6-from-dscp-ipv6 translation table type is supported for IPv6 packets.
Only the to-exp-from-exp translation table type is supported for MPLS packets.

Note: Translation tables are not supported if fixed classification is configured on the logical interface.

The following example translates incoming DSCP values to the new values listed in the table. All incoming DSCP values other than 111111, 111110, 000111, and 100111 will be translated to 000111.



[edit class-of-service]
translation-tables {


to-dscp-from-dscp dscp-trans-table {
to-code-point 000000 from-code-point 111111;
to-code-point 000001 from-code-point 111110;
to-code-point 111000 from-code-point [ 000111 100111 ];
to-code-point 000111 from-code-point *;
}


}

You must apply the translation table to the logical interface input on the Enhanced IQ PIC:



[edit class-of-service interfaces so-1/0/0 unit 0]
translation-tables input to-dscp-from-dscp dscp-trans-table;

A maximum of 32 distinct translation tables are supported on each IQE PIC. However, this maximum is limited by the number of classifiers configured along with translation tables because on the IQE PIC the hardware tables are not always merged. For example, if a translation table and a classifier are both configured on the same logical interface (such as unit 0 ), there is only one hardware table and only one table added to the 32 translation table limit. However, if the translation table is configured on unit 0 and the classifier on unit 1 on the same physical interface, then two hardware tables are used and these two tables count toward the 32 maximum.

You can issue the following operational mode commands to verify your configuration:

show class-of-service translation-table
show class-of-service interface interface-name
show class-of-service forwarding-table translation-table
show class-of-service forwarding-table translation-table mapping

ToS translation on the IQE PIC is a form of behavior aggregate (BA) classification. The IQE PIC does not support multifield (MF) classification of packets at the PIC level. For more information about MF classification, see Classifying Packets Based on Various Packet Header Fields.

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