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Route leaking – H3C Technologies H3C SR8800 User Manual

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Figure 50 IS-IS topology

Figure 51

shows another IS-IS topology. The Level-1-2 routers connect to the Level-1 and Level-2 routers,

and form the IS-IS backbone together with the Level-2 routers. No area is defined as the backbone in this

topology. The backbone comprises all contiguous Level-2 and Level-1-2 routers which can reside in
different areas.

Figure 51 IS-IS topology

NOTE:

The IS-IS backbone does not need to be a specific Area.

Both the Level-1 and Level-2 routers use the SPF algorithm to generate the shortest path tree (SPT).

Route leaking

An IS-IS routing domain is comprised of only one Level-2 area and multiple Level-1 areas. A Level-1 area

consists of a group of Level-1 routers and is connected with a Level-2 area rather than other Level-1 areas.