TCP/IP protocol principles and application Notes 21: routing selection method

1. Route Selection Method

(1) Basic Ideas

• Instead of selecting routes for an IP group, you can obtain all the routes (Routing Protocol) in advance)
• Forward IP packets by a predefined route (route table)

(2) route reservation:Route table(Route table)

• Route tableIt can also be calledForwarding Table)
• HostAndVroRoute tables are used for PacketSend,Forwarding

 

2. Information contained in the route table

(1) thoughts:

UseAs little information as possibleImplement Routing

(2) Information contained:

 

(3) Example:

 

 

(4) discussion:

• Route table sizeOnly related to the number of networks,And the size of each network(Number of hosts included)Irrelevant
• Vro independent routing. The path from net 1 to net 2 may be different from the path from net 2 to net 1:

 

• Only the last vro knowsTarget HostExist?

 

3. Host-specific Routing)

(1) thoughts:

Create a separate route for a host

(2) Implementation:

Mask value all '1' --- host mask

(3) Role: More control

• Delivery path
• Security

 

 

4. Default route)

(1) thoughts

Specify a default vro. When the destination network of the IP Group is not displayed in the routing table, the IP Group is sent to the default vro.

(2) Implementation:

Destination network address =0.0.0.0

Destination network mask =0.0.0.0

(3) Role

• Make the route table small
• Hiding a large amount of network routing information

(4) Example:

 

 

(5) default route settings for hosts and Routers

TCP/IP protocol principles and application Notes 21: routing selection method