Got it

The difference of the DBD packet between a Huawei and a Cisco router

837 0 0 0 0

As we konw, the DBD packets are exchanged between routers to transfer the LSDB. In the DBD packet, there is a MTU field which indicates the interface MTU, if the value mismatch between the routers, the neighbor relationship could not be established.


In the case of a Huawei router, if you guys have noticed, the MTU field in the DBD packet is 0, instead of the MTU vlaue of the interface. This is because the router doesn't set this field to the interface MTU value, just as the picture below shows:


dbd

In the case of a Cisco router, this MTU field is set to the interface MTU value by default: 

dbd - 副本

When the Huawei router connects to the Cisco router, if the interface MTU is modified to 1400, will the neighbor relationship be established successfully? The answer is yes.


However, if we enable the command ospf mtu-enable, the neighbor relationship will not be established successfully, because when enabling the command, the Huawei router will set the MTU field in the DBD packet to the interface MTU value, while the Cisco router enables the MTU inspection by default. So, the router will stuck in exstart.


By the way, we can disable the inspection function on the Cisco router by excuting the command ip ospf mtu-ignore. By doing this, the Cisco router will not check the MTU field. 

  • x
  • convention:

Comment

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

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 " User Agreement."

My Followers

Login and enjoy all the member benefits

Login

Block
Are you sure to block this user?
Users on your blacklist cannot comment on your post,cannot mention you, cannot send you private messages.
Reminder
Please bind your phone number to obtain invitation bonus.
Information Protection Guide
Thanks for using Huawei Enterprise Support Community! We will help you learn how we collect, use, store and share your personal information and the rights you have in accordance with Privacy Policy and User Agreement.