Got it

Different qos fields in IP packets, mpls packets, and vlan packets.

336 0 1 1

When implementing the QoS, we will do that with the help of the diffrent qos field in different packets.

In IP packets, we use the ToS field to adjust the QoS, the first three bits of the ToS represents the IP precedence, the value range is from 0 to 7, the value is bigger, the priority is higher. Now, RFC has redifined the ToS field, the new is call DSCP, the first three bits is called CSCP(class selector code point), and it is compatible with the previous IP preference.


In the case of the VLAN packets, the packet priority is defined by the PRI(PCP) field in 802.1q tag. We should notice that the vlan tag is defined by the 802.1q, while the PCP is not, PCP is defined in 802.1p.

Like the IP precedence, the 3 bits PRI defines 8 priority levels, from 0 to 7, the vlaue is bigger, the priority is higher.


For MPLS packets, the priority is defined by the EXP field. the EXP field also contains 3 bits, defines the priority from 0 to 7, with the value is bigger, the priority is higher.


  • x
  • convention:


You need to log in to comment to the post Login | Register

Notice: To protect the legitimate rights and interests of you, the community, and third parties, do not release content that may bring legal risks to all parties, including but are not limited to the following:
  • Politically sensitive content
  • Content concerning pornography, gambling, and drug abuse
  • Content that may disclose or infringe upon others ' commercial secrets, intellectual properties, including trade marks, copyrights, and patents, and personal privacy
Do not share your account and password with others. All operations performed using your account will be regarded as your own actions and all consequences arising therefrom will be borne by you. For details, see " Privacy."

My Followers

Login and enjoy all the member benefits


Huawei Enterprise Support Community
Huawei Enterprise Support Community
Are you sure to block this user?
Users on your blacklist cannot comment on your post,cannot mention you, cannot send you private messages.
Please bind your phone number to obtain invitation bonus.