RIP

Routing Information Protocol

• cmd:

show ip route

• config:

Mask, Prefix Format

Basic

its metrics & timer

• GW:

Candidate Default Routes & GW of Last Resort

• routing table:

its Content & Update Process

Unicast Routing Updates

• so on:

LB

NBMA

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Show IP Route

the cmd is used to display the routing table of cisco router. And this routing table only contains static and connected routes, so the output of show ip route cmd is simple.

There are 3 sources of routing information:

• Static
• Dynamic
• Connected

And the "Gateway at last resort is not set" denotes the default router that the router shall use if it receive a datagram destined for an IP addr for which it does not have any route.

R0$ show ip route


    Codes: R - RIP
           O - OSPF
           S - Stactic
           U - Per User Static Route
           B - BGP
           i - IS-IS
           * - Candidate Default
           D - EIGRP
       
    Gateway at last resort is not set
       
      R 192.168.2.0/24 [120/2] via 192.168.3.1 00:00:00. Serial0
      |          |       | |           |                      |
      V          |       | |           V                      |
      source of routing info           Next Hop Router        V
                 |       | |                                  Output of interface
                 V       | V
                 Mask    V metrics
                         Distance of Route

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Routing Table Entries

• it specifies the source of routing information that create the routing table entry. Both the indicators and its options are explained in the legend line.

• the subnet mask (a.k.a network prefix) for which the routing table is created.

• the asministrative distance.

• the routing information source metric, said static, then value is 0.

• the ip addr of next hop router en route.

• the output interface to be used to send datagrams destined for IP addr matched by the mask (prefix).

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Network Prefix

https://github.com/QueenieCplusplus/Subnet_mask

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Default GW

https://github.com/QueenieCplusplus/GW

(to be continued)