* dynamic routing-- OSPF routing protocol * brief introduction
Dynamic routing-OSPF routing Protocol
First, internal gateway protocol and external gateway protocol
Ospf is a link-state routing protocol
Ospf Open shortest path first chooses the protocol
OSPF Multicast address: DR/BDR 224.0.0.5
other (other): 244.0.0.6
OSPF: features: suitable for large-scale networks
routing changes converge quickly
has no routing ring
supports variable length subnet mask VLSM
supports zoning
supports sending protocol packets at multicast addresses.
Backbone area: Area 0
Standard area (non-backbone area): Area1, Area2
The selection method of two DR BDR
1, automatic election
The router with the largest router id on the segment will be elected dr, and the second largest router will be elected bdr
2, hand-selected
The priority range of 1 is 0MMI 255. The higher the value, the higher the priority. The default value is 1.
2 if the priority is the same, this compares to touter id.
3 if the router priority is 0, he will not participate in the selection of DR BDR
Note: router priority can affect the election process, but it cannot force the replacement of existing DR, BDR
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Ports in down state can only receive hello packets but not send hello packets when they receive hello packets and activate init state.
After the router system is loaded, it will enter the 2way state from init.
You can either receive hello packets or send hello packets in the 2way state and elect the two largest router id (but DR BDR will not be elected)
When exchange status interaction DBD packet is received at the same time, there will be lsack packet.
Loading status is the busiest, including the most kinds of LSR LSU, etc.
FULL steady state starts forwarding packets
