Routing Protocols Flashcards
RIP Characteristics
• The Routing Information Protocol (RIP) is a Distance Vector
routing protocol
• It uses hop count as its metric
• The maximum hop count is 15
• It will perform Equal Cost Multi Path, for up to 4 paths by default
RIPv2 vs RIPv1
• RiPv1 is a legacy protocol which is not typically used anymore (although it is still supported on Cisco routers)
• RiPv1 does not send subnet mask information with routing updates so Variable Length Subnet Masking (VLSM) is not supported. RIPv2 does support VLSM.
• RIPv1 updates are sent every 30 seconds as broadcast traffic.
RIPv2 uses multicast address 224.0.0.9
• RIPV2 supports authentication, RIPv1 does not this Means you can set password on both side of router
RIPng
• RIPng (RIP next generation) supports IPv6 networks
• It is not covered on the CCNA exam
RIPV2 Configuration commands
R1 (config) #router rip
R1 (config-router) #version 2
R1 (config-router) #network 10. 0.0.0
network’ command should reference a classful network. No subnet mask is specified.
Auto-Summary command in RIP
• RIP will automatically summarise routes to the classful boundary by default
• For example, 192.168.10.1/30 will be advertised as 192.168.10.0/24
• 172.16.10.1/30 will be advertised as 172.16.0.0/16
• This is almost never desirable
R1 (config) #router rip
R1 (config-router) #no auto-summary
That is almost never desirable. Unless by some magical coincidence your network, the summarization does fall exactly in the classful boundaries, in which case, it would be fine.Your network, modern real networks, aren’t designed that they all fall into the summarization ranges exactly on classical boundaries. So, if you leave auto-summary turned on, it’s liable to cause have on your network, possibly blackholing, dropping some of your traffic.So, we always disable auto-summary. To do that, the commands is ‘router rip’ and then no auto-summary.
Manual Summarization in RIP
• Manual summarisation gives you control of exactly how you summarise
• The individual summarised routes are not advertised - only their summary
route
(config-router) #interface f1/0 h
(config-if)#ip summary-address rip 10.0.0.0 255.255.0.0
want to do the automatic summarization, but we probably still will want to do summarization manually. To do that, the command is ‘ip summary-address. So, we would do this to get control of exactly how we are summarizing.When we do this,
the individual summarized routes that fall within the larger range are not going to be advertised, only the summary route. So in the neighbor router that learns the route, it’s not going to learn all those different individual route. It will only learn the summary route. It’s more efficient and it takes up less memory. It also compartmentalizes
the different parts of your network. So if you have an outage anywhere, it’s going to limit the impact that that has network wide
RIPv2 Verification commands
- show ip protocols
- sh ip route
- sh rip database
-R1#sh run | section rip
router rip version 2
network 10.0.0.0
no auto-summary
Default Route Injection in rip
R4 (config)#ip route 0.0.0.0 0.0.0.0 203.0.113.2
R4 (config) #router rip
R4 (config-router) #default-information originate
This is where we have got a default static route for all traffic probably going out to the Internet, and we don’t want to have to configure a default static route on every single router.
So what we’ll do is on the final outbound router, which is connected out to the Internet, we will configure a default static route there, and we will then advertise, it inject it into RIP, so all of our other internal routers will learn about it automatically. Saves us having to do a static route for it on every single router in the organization.
What is a Passive Interface?
A passive interface is an interface where a routing protocol does not send updates but can still receive them (depending on the protocol).
Why Use a Passive Interface?
1. Security – Prevents exposing routing information on interfaces connected to end devices (like PCs or servers).
2. Efficiency – Reduces unnecessary bandwidth usage by stopping unneeded routing advertisements.
3. Stability – Avoids routing loops and unnecessary updates in networks where only one-way communication is needed.
How It Works in RIP:
router rip
passive-interface GigabitEthernet 0/1
This stops RIP from sending updates on GigabitEthernet 0/1. Since RIP does not receive updates on passive interfaces either, this means no RIP learning will happen on that interface.
Important Notes:
• In OSPF and EIGRP, passive interfaces still receive updates (so they can learn routes but don’t send advertisements).
• In RIP, a passive interface neither sends nor receives RIP updates.
Key Takeaways:
• Passive interfaces in RIP stop both sending and receiving updates on that interface.
• In OSPF and EIGRP, passive interfaces only stop sending updates but still receive them (different from RIP).
• This helps keep the network secure and efficie
• By default, RIP sends updates every 30 seconds on all configured interfaces. • When you set an interface as passive, RIP stops sending updates on that interface. • However, in RIP, a passive interface also stops receiving updates, meaning it won’t learn new routes from that interface.
Example Scenario:
Imagine a router with these interfaces:
• GigabitEthernet 0/0 – Connected to another router (should exchange RIP updates).
• GigabitEthernet 0/1 – Connected to a LAN with computers (no need to send RIP updates).
Command to Configure a Passive Interface in RIP:
