Intermediate Systems And End Systems - Dell PowerConnect B-RX Configuration Manual

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Configuring IS-IS (IPv4)
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The administrative distance is a protocol-independent value from 1 – 255. Each path sent to the
CPU, regardless of the source of the path (IS-IS, OSPF, static IP route, and so on) has an
administrative distance.
Each route source has a default administrative distance. The default administrative distance for
IS-IS is 115.
You can change the administrative distance for IS-IS and other routes sources.

Intermediate systems and end systems

IS-IS uses the following categories to describe devices within an IS-IS routing domain (similar to an
OSPF Autonomous System):
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•
When you configure IS-IS on a device, the device is an IS.
Figure 117
FIGURE 117
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If the path provided by IS-IS has the lowest administrative distance, then the CPU places that
IS-IS path in the IP route table.
If a path to the same destination supplied by another protocol has a lower administrative
distance, the CPU installs the other protocol's path in the IP route table instead.
Intermediate System (IS) – A device capable of forwarding packets from one device to another
within the domain. In Internet Protocol (IP) terminology, an IS is a router.
End System (ES) – A device capable of generating or receiving packets within the domain. In IP
terminology, an ES is an end node or IP host.
shows an example of an IS-IS network.
An IS-IS network contains Intermediate Systems (ISs) and host systems
Router A
IP
IP
Host
Host
An IS-IS routing domain can
contain multiple areas.
IS-IS routers route within an
area at Level-1.
IS-IS routers route between
areas at Level-2.
IS-IS Routing Domain
IS-IS Area 1
Router C
Router B
IP
Host
IS-IS Area 2
Router D
BGP4
Router E
BigIron RX Series Configuration Guide
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