[Lsr] 答复: LSR Working Group Adoption Call for "Hierarchical IS-IS" - draft-li-lsr-isis-hierarchical-isis-01

["Aijun Wang" <[e-mail]>]

Hi, Tony:

 

Would you like to elaborate this in more detail to show how you design the control plane hierarchically but the traffic can be transported horizontally? Let’s consider the following graph:

 



If, as you stated,  we connect R1 and R7 via one link(although we will not do so, if we design the network hierarchically), how you flood the link information hierarchically but let the traffic between the two connected L1 area bypass the L2 area?

 

 

Best Regards.

 

Aijun Wang

China Telecom

 

 

 

发件人: [e-mail] [mailto:[e-mail]] 代表 [e-mail]
发送时间: 2019年8月15日 23:37
收件人: Robert Raszuk
抄送: [e-mail]; Aijun Wang
主题: Re: [Lsr] LSR Working Group Adoption Call for "Hierarchical IS-IS" - draft-li-lsr-isis-hierarchical-isis-01

 

 

Hi Robert,

 





> The hierarchical arrangement of the control plane does NOT imply that the data plane is necessarily hierarchical.  

 

Since Aijun posted his question I was trying to think of such model, but failed. 

 

While it is easy to envision this with DV protocols say BGP - do you have any pointer to a link state protocol architecture where data plane is non hierarchical (links do not belong to upper levels) while control plane used traverses multiple levels ? 

 

 

Consider any topology where two peer areas intersect.  At the intersection, traffic can transition between the areas without entering the parent level.

 

While I’m at it, I should also point out that the existence of hierarchy for the control plane does not mandate its use. This is another tool in the toolbox. Use the right tool for the job at hand.

 

Tony