| LIB (Label Information Base)
tables are loaded using Independent Control or Ordered Control.
Under Independent Control each router can listen to routing
information flooded by other routers, and based on this information creates
its own table. Then this information is flooded to the rest of the routers.
This mode has the advantage that any router can listen to routing protocols
(i.e., OSPF, IS-IS), generates its own table and distribute
it. The system converge faster after any update. Problem is that not having
a centralized point of control, traffic engineering is more difficult to
achieve. |
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| When Ordered Control is used, one
router, typically an egress LER router for dynamic configuration, or
an ingress LER router for static configuration, is responsible for
distributing the label information. Control is then centralized and better
achieved. Disadvantage are that the system converge slowly in case of any
update, and the controller router represents a single point of failure. |
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| When Independent Control is used,
labels are binded with FEC independently by the down-stream routers in a
way known as Down-stream Unsolicited (DOU). When Ordered
Control is used, labels are binded with FEC by the down-stream
routers when they demand the kind of binding to the Label Manager Router.
This method is known as Down-stream on Demand (DOD). |
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| The LIB tables contain the following
information: label-in, port-in, label-out, port-out,
and instructions. Once the LIB tables are loaded the data can
begin to flow through the designated LSP. |
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