topic How many bits reserved in 802.1Q and ISL header for QoS? in Switching https://community.cisco.com/t5/switching/how-many-bits-reserved-in-802-1q-and-isl-header-for-qos/m-p/1632642#M166326 <P>Please help - How many bits are reserved in 802.1q and ISL header for QoS.</P><P></P><P>Thanks in Advance</P><P>-Jigar</P> Wed, 06 Mar 2019 22:40:38 GMT Jigar Dave 2019-03-06T22:40:38Z How many bits reserved in 802.1Q and ISL header for QoS? https://community.cisco.com/t5/switching/how-many-bits-reserved-in-802-1q-and-isl-header-for-qos/m-p/1632642#M166326 <P>Please help - How many bits are reserved in 802.1q and ISL header for QoS.</P><P></P><P>Thanks in Advance</P><P>-Jigar</P> Wed, 06 Mar 2019 22:40:38 GMT https://community.cisco.com/t5/switching/how-many-bits-reserved-in-802-1q-and-isl-header-for-qos/m-p/1632642#M166326 Jigar Dave 2019-03-06T22:40:38Z Re: How many bits reserved in 802.1Q and ISL header for QoS? https://community.cisco.com/t5/switching/how-many-bits-reserved-in-802-1q-and-isl-header-for-qos/m-p/1632643#M166327 <HTML><HEAD></HEAD><BODY><P>Hi Jigar,</P><P></P><P>For 802.1Q, 3 bits are reserved, yielding 8 different CoS classes. For ISL, there appear to be 2 bits reserved for priority purposes, yielding 4 different CoS classes. See the following URL for more info:</P><P></P><P><A class="jive-link-external-small" href="http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080094665.shtml">http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080094665.shtml</A></P><P></P><P>Best regards,</P><P>Peter</P></BODY></HTML> Thu, 23 Dec 2010 10:16:32 GMT https://community.cisco.com/t5/switching/how-many-bits-reserved-in-802-1q-and-isl-header-for-qos/m-p/1632643#M166327 Peter Paluch 2010-12-23T10:16:32Z