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Box forwarding entails 2 features:
Route dedication perform
Changing perform
The road dedication perform may be the procedure for the way the router decides that road to make use of whenever forwarding the box. To look for the greatest route, the actual router queries it's redirecting desk for any system tackle which fits the actual packet's location IP tackle.
Among 3 route determinations outcomes out of this research:
Straight Linked System -- When the location IP tackle from the box goes to some gadget on the system that's straight attached to among the router's interfaces, which box is actually submitted straight to which gadget. Which means that the actual location IP tackle from the box is really a web host tackle on a single system because this particular router's user interface.
Remote control System -- When the location IP tackle from the box goes to some remote control system, then your box is actually submitted to a different router. Remote control systems may just end up being arrived at through forwarding packets to a different router.
Absolutely no Path Decided -- When the location IP tackle from the box doesn't fit in with whether linked or even remote control system, and when the actual router doesn't have the default path, then your box is actually thrown away. The actual router transmits a good ICMP unreachable information towards the supply IP tackle from the box.
Within the very first 2 outcomes, the actual router re-encapsulates the actual IP box to the Coating two information hyperlink body structure from the leave user interface. The kind of Coating two encapsulation is dependent upon the kind of user interface. For instance, when the leave user interface is actually FastEthernet, the actual box is actually exemplified within an Ethernet body. When the leave user interface is really a serial user interface set up with regard to PPP, the actual IP box is actually exemplified inside a PPP body.
The next area shows this method.
