Concept Guide

Creating a Layer 2 Class Map

All class maps are Layer 3 by default; however, you can create a Layer 2 class map by specifying the layer2 option with the class-map

command.

A Layer 2 class map dierentiates trac according to 802.1p value and/or VLAN and/or characteristics dened in a MAC ACL..

Use Step 1 or Step 2 to start creating a Layer 2 class map.

1 Create a match-any class map.

CONFIGURATION mode

class-map match-any

2 Create a match-all class map.

CONFIGURATION mode

class-map match-all

3 Specify your match criteria.

CLASS MAP mode

[seq sequence number] match mac

After you create a class-map, Dell EMC Networking OS places you in CLASS MAP mode.

Match-any class maps allow up to ve access-lists. Match-all class-maps allow only one. You can match against only one VLAN ID.

4 Link the class-map to a queue.

POLICY MAP mode

service-queue

Determining the Order in Which ACLs are Used to Classify Trac

When you link class-maps to queues using the service-queue command, Dell EMC Networking OS matches the class-maps according

to queue priority (queue numbers closer to 0 have lower priorities).

For example, as described in the previous example, class-map cmap2 is matched against ingress packets before cmap1.

ACLs acl1 and acl2 have overlapping rules because the address range 20.1.1.0/24 is within 20.0.0.0/8. Therefore (without the keyword

order), packets within the range 20.1.1.0/24 match positive against cmap1 and are buered in queue 7, though you intended for these

packets to match positive against cmap2 and be buered in queue 4.

In cases such as these, where class-maps with overlapping ACL rules are applied to dierent queues, use the keyword order. Dell EMC

Networking OS writes to the CAM ACL rules with lower order numbers (order numbers closer to 0) before rules with higher order numbers

so that packets are matched as you intended.

• Specify the order in which you want to apply ACL rules using the keyword order.

order

The order can range from 0 to 254.

By default, all ACL rules have an order of 255.

Quality of Service (QoS)

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