2.2.1.1.20 QoS Characteristics
The QoS Characteristics attribute specifies various QoS–related characteristics of the responder host and network interface. This attribute is mandatory for responders that support layer 2 forwarding, VLAN tagging, or 802.1p priority tagging; implementations MUST include it in all Hello frames.
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Type |
Length |
E |
Q |
P |
Reserved |
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Type (1 byte): This field MUST be set to 0x14.
Length (1 byte): This field MUST be set to 0x04.
E (1 bit): This field MUST be set if the responder is not providing any Layer 2 forwarding between segments on this link.
Q (1 bit): This field MUST be set if the interface supports 802.1q virtual local area network (VLAN) tagging, as specified in [IEEE802.1Q] section 9.
P (1 bit): This field MUST be set if the network interface supports setting the User Priority field in the Tag Control Information of the tag header (802.1p priority tagging), as specified in [IEEE802.1Q] section 9.3.2.1
Reserved (13 bits): MUST be set to zero when sent and MUST be ignored on receipt.