Routing management data
The following scenario describes routing management data in a divisioned network.
Suppose a node A wants to send messages to another node. If this node is in its own
area (determined by the area ID part in the area address field), the messages from A to
this particular node (B) are routed directly using the level 1 intermediate system (see
previous figure).
Alternatively, if the required destination is in a different area (C), the messages are sent
to a second, higher level (level 2) intermediate system. This intermediate system routes
the messages coming from node A to other level 2 intermediate systems until they
reach a level 2 intermediate system attached to the destination area of C. From there it
is routed within the area using level 1 intermediate systems to node C.
Notice that in both of the above cases the ES-ES communication between nodes in the
same or in different areas is still possible.
OSI-DCN networks types
In general, the OSI-DCN network can be classified in three types:
•
Undivided
•
IS-IS clustered
•
IS-IS area divided network
Undivided network definition
An undivided network consists of a single routing domain. There is no division
between the nodes at the network protocol level. All nodes in the network and
especially the intermediate systems can exchange routing information with each other.
ES
Level 1 IS
Level 2 IS
Level 2 subdomain
A
B
C
Area 4
Area 3
Area 2
Area 1
Management communication setup concepts
DCN configurations
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365-312-875R5.2
Issue 1, March 2007
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