3com S7906E 설치 설명서

 

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Each LSP set up using RSVP-TE is assigned a resource reservation style. During an RSVP session, 
the receiver decides which reservation style can be used for this session and thus which LSPs can be 
used. 

Currently, two reservation styles are available: 

z

 

Fixed-filter style (FF) where resources are reserved for individual senders and cannot be shared 
among senders on the same session. 

z

 

Shared-explicit style (SE) where resources are reserved for senders on the same session and 
shared among them. 

 

At present, SE is only used for make-before-break because multiple LSPs cannot be present on the 
same session. 

 

Make-before-break is a mechanism to change MPLS TE tunnel attributes with minimum data loss and 
without extra bandwidth. 

Diagram for make-before-break 

 

 

 presents a scenario where a path Router A → Router B → Router C → Router D is 

established with 30 Mbps reserved bandwidth between Router A and Router D. The remaining 
bandwidth is then 30 Mbps.  

If 40 Mbps path bandwidth is requested, the remaining bandwidth of the Router A → Router B → Router 
C → Router D path will be inadequate. The problem cannot be addressed by selecting another path, 
Router A → Router E → Router C → Router D, because the bandwidth of the Router C → Router D link 
is inadequate. 

To address the problem, you may use the make-before-break mechanism. It allows the new path to 
share the bandwidth of the original path at the Router C → Router D link. Upon creation of the new path, 
traffic is switched to the new path and the previous path is torn down. This helps avoid traffic interruption 
effectively. 

RSVP-TE uses RSVP messages with extensions. The following are RSVP messages: