Description

On EX series switch, you may observe syslog message below when changing configuration or rebooting device.

Jun 24 11:34:45 Switch cosd[10505]: COSD_CLASSIFIER_STACKING_NOT_SUPPORTED: Interface xe-0/0/0.0 already has classifier mapped and supports only one among DSCP/DSCP-IPv6/IPPrec. Skipping defaults

This is harmless message which you can ignore unless configuring custom CoS. This KB describes the details of this message.

NOTE: This KB can be applied to all EX series switch except EX9200 and EX4300.

Symptoms

On EX series switch such as EX4400, you may observe syslog message below when changing configuration or rebooting device. Even if using a default CoS config, you may see this message. 
Jun 24 11:34:45 Switch cosd[10505]: COSD_CLASSIFIER_STACKING_NOT_SUPPORTED: Interface xe-0/0/0.0 already has classifier mapped and supports only one among DSCP/DSCP-IPv6/IPPrec. Skipping defaults
The interface in this message has the setting of IPv4 and IPv6 address. The message is not seen when configuring one of them.

Solution

You can ignore this message on EX series switch as it does not support IPv4 & IPv6 classifiers on the same interface. Here is the details:
1. Each IFL per IFF (family inet/inet6) will create a default classifier per family.
2. The display of an error message is an expected behavior, since these platforms do not support per protocol classifier on the same interface.
3. This behavior is there on EX side, apart from other Juniper platforms, but syslog message is seen as it is common among Junos products.
4. If we apply custom cos configs, a commit failure is encountered as below: 
user@Switch# commit 
[edit class-of-service interfaces ge-0/0/1 unit <>]
  'classifiers'
    can not bind both IPv4 & IPv6 classifiers on this platform for an interface: ge-0/0/1
error: configuration check-out failed
5. You can find the document below:
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If you have not explicitly configured a classifier on a logical interface, the default classifiers are assigned and classification works as follows:
  • To a logical interface configured with an IPv4 address, a DSCP classifier is assigned by default, and IPv4 and IPv6 packets are classified using the DSCP classifier.
  • To logical interface configured with an IPv6 address, a DSCP IPv6 classifier is assigned by default, and IPv4 and IPv6 packets are classified using the DSCP IPv6 classifier.

https://www.juniper.net/documentation/us/en/software/junos/cos-ex/topics/concept/cos-ex-series-classifiers-understanding.html
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6. You can check output of "show class-of-service classifier type dscp" and "show class-of-service classifier type dscp-ipv6", both outputs must be the same, so there is no behavior change no matter which classifier was assigned to IPv4 and IPv6 enabled interface.

Modification History

2024-06-23 : Article Created