02.10.2013 Views

FTOS Configuration Guide for the C-Series - Force10 Networks

FTOS Configuration Guide for the C-Series - Force10 Networks

FTOS Configuration Guide for the C-Series - Force10 Networks

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

An AS can be divided into a number of areas, which are groups of contiguous networks and<br />

attached hosts. Routers with multiple interfaces can participate in multiple areas. These routers,<br />

Area Border Routers (ABRs), maintain separate databases <strong>for</strong> each area. Areas are a logical<br />

grouping of OSPF routers identified by an integer or dotted-decimal number.<br />

Areas allow you to fur<strong>the</strong>r organize your routers within in <strong>the</strong> AS. One or more areas are required within<br />

<strong>the</strong> AS. Areas are valuable in that <strong>the</strong>y allow sub-networks to "hide" within <strong>the</strong> AS, thus minimizing <strong>the</strong><br />

size of <strong>the</strong> routing tables on all routers. An area within <strong>the</strong> AS may not see <strong>the</strong> details of ano<strong>the</strong>r Area's<br />

topology. AS areas are known by <strong>the</strong>ir area number or <strong>the</strong> router’s IP address.<br />

Figure 375 Autonomous System Areas<br />

Router E<br />

Area 100<br />

Router A<br />

Area Types<br />

Router F<br />

Router B<br />

Router D<br />

Router C<br />

Area 0<br />

Router K<br />

Router I<br />

Area 300<br />

Area 200<br />

Router J<br />

Router M<br />

Router H<br />

Router L<br />

Router G<br />

The Backbone of <strong>the</strong> network is Area 0. It is also called Area 0.0.0.0 and is <strong>the</strong> core of any Autonomous<br />

System (AS). All o<strong>the</strong>r areas must connect to Area 0. Areas can be defined in such a way that <strong>the</strong><br />

backbone is not contiguous. In this case, backbone connectivity must be restored through virtual<br />

links. Virtual links are configured between any backbone routers that share a link to a<br />

non-backbone area and function as if <strong>the</strong>y were direct links.<br />

530 Open Shortest Path First

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!