Is-Is Network Type; Dis And Router Priority - Zte ZXR10 5900E Series User Manual

Chapter 4 IS-IS Configuration
F 10 IS-IS AREAS
IGURE

IS-IS Network Type

There are two network types in IS-IS: broadcast network and
point-to-point network which make IS-IS easy for configuration
and implementation.

DIS and Router Priority

In a broadcast network IS-IS protocol is similar to OSPF protocol
and uses designated router (DIS that is Designated Intermediate
System). The DIS is responsible for advertising network infor-
mation to all routers on the broadcast network and meanwhile all
other routers only advertise one adjacency to the DIS.
The router priority parameters can be IS-IS configured for DIS
election. L1 and L2 can be independently IS-IS configured with
different priorities. Upon DIS election, a highest priority router
plays the role of DIS.
If priorities are same for a frame relay interface, a router with
higher router ID will be elected as the DIS. While for an Ethernet
interface, a router with higher interface MAC value will be elected
as the DIS.
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