RIP Routing information protocol
Routing Information Protocol (RIP) is a standards-based, distance-vector, interior gateway protocol (IGP) used by routers to exchange routing information. RIP uses hop count to determine the best path between two locations. Hop count is the number of routers the packet must go through till it reaches the destination network. The maximum allowable number of hops a packet can traverse in an IP network implementing RIP is 15 hops.
it has a maximum allowable hop count of 15 by default, meaning that 16 is deemed unreachable. RIP works well in small networks, but it's inefficient on large networks with slow WAN links or on networks with a large number of routers installed.
In a RIP network, each router broadcasts its entire RIP table to its neighboring routers every 30 seconds. When a router receives a neighbor's RIP table, it uses the information provided to update its own routing table and then sends the updated table to its neighbors.
Differences between RIPv1 or RIPv2
RIPv1
- A classful protocol, broadcasts updates every 30 seconds, hold-down period 180 seconds. Hop count is metric (Maximum 15).
- RIP supports up to six equal-cost paths to a single destination, where all six paths can be placed in the routing table and the router can load-balance across them. The default is actually four paths, but this can be increased up to a maximum of six. Remember that an equal-cost path is where the hop count value is the same. RIP will not load-balance across unequal-cost paths
RIPv2
- RIPv2 uses multicasts, version 1 use broadcasts,
- RIPv2 supports triggered updates—when a change occurs, a RIPv2 router will immediately propagate its routing information to its connected neighbors.
- RIPv2 is a classless protocol. RIPv2 supports variable-length subnet masking (VLSM)
- RIPv2 supports authentication. You can restrict what routers you want to participate in RIPv2. This is accomplished using a hashed password value.
RIP Timers
RIP uses four different kinds of timers to regulate its performance:
Route update timer
Sets the interval (typically 30 seconds) between periodic routing updates in which the router sends a complete copy of its routing table out to all neighbors.
Route invalid timer
Determines the length of time that must elapse (180 seconds) before a router determines that a route has become invalid. It will come to this conclusion if it hasn’t heard any updates about a particular route for that period. When that happens, the router will send out updates to all its neighbors letting them know that the route is invalid.
Holddown timer
This sets the amount of time during which routing information is suppressed. Routes will enter into the holddown state when an update packet is received that indicated the route is unreachable. This continues either until an update packet is received with a better metric or until the holddown timer expires. The default is 180 seconds.
Route flush timer
Sets the time between a route becoming invalid and its removal from the routing table (240 seconds). Before it's removed from the table, the router notifies its neighbors of that route's impending failure. The value of the route invalid timer must be less than that of the route flush timer. This gives the router enough time to tell its neighbors about the invalid route before the local routing table is updated.
Rip Routing configurations
We will use two router and four subnet. Create a topology as shown in figure on packet tracer.
| Router | FastEthernet 0/0 | FastEthernet 0/1 | Serial 0/0/0 |
| R1 | 10.0.0.1 | 20.0.0.1 | 50.0.0.1 |
| R2 | 30.0.0.1 | 40.0.0.1 | 50.0.0.2 |
| PC | IP Address | PC | IP Address |
| PC0 | 20.0.0.2 | PC1 | 20.0.0.3 |
| PC2 | 40.0.0.2 | PC3 | 40.0.0.3 |
| PC4 | 10.0.0.2 | PC5 | 10.0.0.3 |
| PC6 | 30.0.0.2 | PC7 | 30.0.0.3 |
Assign ip address to PC. Select pc and double click on it. select ip configurations from desktop tab and set ip address given as in table.
To configure router double click on it and select CLI.To configure this topology use this step by step guide.
(1841Router0) Hostname R1
To configure and enable rip routing on R1 follow these commands exactly.
Router>enable Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#hostname R1 R1(config)#interface fastethernet 0/0 R1(config-if)#ip address 10.0.0.1 255.0.0.0 R1(config-if)#no shutdown %LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up R1(config-if)#exit R1(config)#interface fastethernet 0/1 R1(config-if)#ip address 20.0.0.1 255.0.0.0 R1(config-if)#no shutdown %LINK-5-CHANGED: Interface FastEthernet0/1, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up R1(config-if)#exit R1(config)#interface serial 0/0/0 R1(config-if)#ip address 50.0.0.1 255.0.0.0 R1(config-if)#clock rate 64000 R1(config-if)#bandwidth 64 R1(config-if)#no shutdown %LINK-5-CHANGED: Interface Serial0/0/0, changed state to down R1(config-if)#exit R1(config)#router rip R1(config-router)#network 10.0.0.0 R1(config-router)#network 20.0.0.0 R1(config-router)#network 50.0.0.0
(2811Router1) Hostname R2
To configure and enable rip routing on R2 follow these commands exactly.
Router>enable Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#hostname R2 R2(config)#interface fastethernet 0/0 R2(config-if)#ip address 30.0.0.1 255.0.0.0 R2(config-if)#no shutdown %LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up R2(config-if)#exit R2(config)#interface fastethernet 0/1 R2(config-if)#ip address 40.0.0.1 255.0.0.0 R2(config-if)#no shutdown %LINK-5-CHANGED: Interface FastEthernet0/1, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up R2(config-if)#exit R2(config)#interface serial 0/0/0 R2(config-if)#ip address 50.0.0.2 255.0.0.0 R2(config-if)#no shutdown %LINK-5-CHANGED: Interface Serial0/0/0, changed state to up R2(config-if)# %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0, changed state to up R2(config-if)#exit R2(config)#router rip R2(config-router)#network 30.0.0.0 R2(config-router)#network 40.0.0.0 R2(config-router)#network 50.0.0.0 R2(config-router)#exit
To test rip routing do ping from pc0 to all pc and vice versa. If you get replay then you have successfully configured rip routing but if you did not get replay double check this configuration and try to troubleshoot. I have uploaded a configured and tested topology in case you are unable to locate the problem spot then download this configuration file. And try to find out where have you committed mistake
In our next article we will learn advance configuration of RIP routing.
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