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Hierarchy between two LSRs

  • From: Bhupesh Bajaj <bhupeshb@in.huawei.com>
  • Date: Thu, 17 May 2001 18:37:05 +0500
  • Cc: mpls@UU.NET, mpls-ops@mplsrc.com
  • Importance: high

hi,
according to what i interpret from your question ...
 
the hierarchy in a domain will be specified ( indirectly ) by the administrators...it not that one installs certain LSR's and the hierarchy comes into picture by itself ...i believe that hierarchy's concept comes into picture in case of different services of ISP's
 
e.g..
 
-------------------------------------------------------------------------------
                                                                                |
          --------------    ----------------                                    |
         |              |   |                |                     C            |            D
         |      A      |   |     B         |                                  |
         |________|   |_________ |                                  |
                                                                                |
                                                                                |   
_____________________________________________ |
 
Now here for example we have different domains A B and C ..hierarcy comes into picture when we have that
C domain is controlled by one ISP , A by another ISP ...and B by yet another ISP....
 
so for sending a packet from say ...A ...to D ...say passing thru B is required , Now as the domain changes the label stackin will be done...
 
now as you asked , how does LDP / CR-LDp comes to know that its going to have hierarchy, that will be done indirectly by administration , cos administrator will create domains will separate out domains....so once the LSRs know that its Egress / Ingress to its domain , the LDP will ofcourse do label distribution accordingly.
 
i hope it helps....
 
correct me if i am wrong..
 
thanks
bhupesh
-----Original Message-----
From: Asish Thomas Punnoose [mailto:asish.punnoose@wipro.com]
Sent: Thursday, May 17, 2001 5:20 PM
To: mpls@UU.NET
Subject: Hierarchy between two LSRs

hello
 
I am new to MPLS and i have a basic doubt.
 
If hierarchy is introduced between two LSRs, how does LDP/ CR-LDP know whether a hierarchy exists between the two. 
 
How does the label switching work in this situation.
 
Please do help and could someone send some pointers related to this topic.
 
Thanks in advance 
 
Asish Thomas