CCNA Study Guide Chapter 08 – 2000Trainers.com

CCNA Study Guide Chapter 8 Summary

This chapter began with an introduction to routing, including a look at the difference between routed (IP and IPX) and routing (RIP and IGRP) protocols. The communication process on a simple one-router network was described step-by-step, and included an overview of the different processes that take place when a host on one network attempts to communicate with a host on another. A more complex example, involving multiple routers and networks demonstrated the way in which routers will forward packets to the next-hop address on their journey between a source and destination host on different networks.

A look at static routing provided an overview of how this technique allows an administrator to manually define the path that a router will choose in reaching a network. This included a look at the IP routing table, and the syntax of the ip route command. The concept of administrative distances was also introduced, in order to illustrate how a router makes decisions on which routing table entry to use when a path to the same network is learned in different ways. For example, a static routing table entry will always be considered more trustworthy than a route learned from a routing protocol by default.

A look at dynamic routing demonstrated how routers are capable of exchanging routing table information with one another, both through the use of distance vector and link state routing protocols. The major differences between both types of routing protocols were outlined, as was the concept of a hybrid protocol. The danger of routing loops was also discussed, including a look at the techniques used by distance vector protocols to avoid these loops.

An overview of the distance-vector Routing Information Protocol outlined its major characteristics, timer values, and finally the commands to configure and monitor RIP on a Cisco router. The Interior Gateway Routing Protocol was also discussed, including an overview of its configuration. Default routing was looked at as a way to configure a gateway of last resort, the next-hop router to whom a router will send packets destined for unknown networks.

IPX routing was looked at next, including the fact that IPX RIP and SAP messages are broadcast between routers automatically after issuing the ipx routing command. The IPX routing table was looked at, as were the commands to monitor IPX RIP and SAP broadcast traffic. The show protocols command outlined a quick an effective way to obtain information on a router’s interfaces, including their current state and configured addresses.

Routing IPX

For the purpose of both the CCNA and CCDA, you’ll also need to be familiar with routing IPX traffic across an internetwork. Recall from Chapter 7 that IPX functionality is enabled on a router through the use of the ipx routing command. After issuing this command, you can assign IPX addresses to interfaces by providing a network number, and optionally (on Ethernet, Token Ring, or FDDI interfaces) specifying an encapsulation type.

Setting up IPX routing is exceptionally simple. What I didn’t tell you in the last chapter is that after issuing the ipx routing command, your router is already running an IPX routing protocol – IPX RIP. Though much like the RIP protocol looked at previously, IPX RIP and IP RIP are not compatible – they are different routing protocols, even if they exhibit similar characteristics. For example, both define infinity as 16 hops, meaning that the maximum diameter of an IPX network running IPX RIP is 15 hops. IPX RIP update packets are broadcast every 60 seconds by default.

One major difference between the IP and IPX versions of RIP is the metric used. IPX RIP uses something referred to as a “tick” as its metric. A tick is the expected delay in reaching a network, and is defined as 1/18th of a second. In cases where the tick count between two networks is equal, hop count is used as the tiebreaker.

Figure: IPX network configuration.

For the purpose of illustrating IPX routing, we’re going to configure our routers as per the figure above. In this scenario we have two routers and three networks. The steps below outline the configuration of Router A.

RouterA#config t Enter configuration commands, one per line. End with CNTL/Z. RouterA(config)#ipx routing RouterA(config)#int s0 RouterA(config-if)#ipx network 99 RouterA(config-if)#int e0 RouterA(config-if)#ipx network 102A

The configuration of Router B is similar:

RouterB#config t Enter configuration commands, one per line. End with CNTL/Z. RouterB(config)#ipx routing RouterB(config)#int s0 RouterB(config-if)#ipx network 99 RouterB(config-if)#int e0 RouterB(config-if)#ipx network 101A

With only the few steps shown, we have enabled IPX on the routers, given the appropriate interfaces IPX addresses, and even enabled IPX RIP routing – recall that it is enabled automatically as part of the ipx routing command. The next step is taking a look at our IPX routing tables. This is done using the show ipx route command, which is shown on

Router A below. RouterA#sh ipx route Codes: C - Connected primary network, c - Connected secondary network S - Static, F - Floating static, L - Local (internal), W - IPXWAN R - RIP, E - EIGRP, N - NLSP, X - External, A - Aggregate s - seconds, u - uses, U - Per-user static 3 Total IPX routes. Up to 1 parallel paths and 16 hops allowed. No default route known. C 99 (HDLC), Se0 C 102A (NOVELL-ETHER), Et0 R 101A [07/01] via 99.0060.5cc4.f41b, 13s, Se0

Notice that an IPX routing table has a slightly different format, but still displays similar information to an IP routing table. It shows that networks 99 and 102A are directly connected, and also shows a route to network 101A via IPX address 99.0060.5cc4.f41b, which is the S0 interface on Router B. To check and see whether Router A can route all the way to network 101A properly, we can use an IPX ping, specifying the IPX address of interface E0 on Router B.

Router#ping ipx 101a.0060.5cc4.f88b Type escape sequence to abort. Sending 5, 100-byte IPXcisco Echoes to 101a.0060.5cc4.f88b, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 32/35/36 ms

Since our IPX ping worked, Router A and Router B are both configured with complete information about the IPX internetwork.

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Default Routing

In the same way that you can set a default gateway on your desktops and servers, you can also set a default gateway of sorts on your Cisco router – the gateway of last resort. While the name is different, the function is the same. Remember that when a router comes across a packet destined for an unknown network, it automatically drops the packet. If we specify a gateway of last resort, a router will forward traffic for networks that it doesn’t know about to the destination router address we specify.

Figure: Router B configured with a default route, also known as a gateway of last resort.

Consider the figure above, in which Router A is connected to many different networks. Router B, on the other hand, is only connected to two networks. In order to allow Router B to get to all of the other networks shown, we would either need to configure a routing protocol (like RIP or IGRP), or define static routes to each network. In this particular scenario, it might actually be easier to use default routing to allow Router B to reach those three networks. Remember that Router B already knows about networks 10.0.40.0/24 and 10.0.50.0/24, since they are directly connected. In order to have Router B forward all traffic destined for other networks to Router A, we should configure a gateway of last resort on Router B. This involves a single routing table entry, with a destination network of 0.0.0.0. If you recall from Chapter 5, this address literally means “all networks”. In other words, we are saying that all other networks can be reached via Router A. When Router B attempts to route packets, it will first look in its routing table for the destination network. If it doesn’t find an entry, it will forward packets to the default route specified.

To configure the gateway of last resort on Router B, use the ip route command, as shown below.

RouterB(config)#ip route 0.0.0.0 0.0.0.0 10.0.40.1 RouterB(config)#^Z RouterB#sh ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is 10.0.20.1 to network 0.0.0.0 10.0.0.0/24 is subnetted, 2 subnets C 10.0.50.0 is directly connected, Ethernet0 C 10.0.40.0 is directly connected, Serial0 S* 0.0.0.0/0 [1/0] via 10.0.40.1

Notice that the static route entry used 0.0.0.0 for both the destination IP address and subnet mask, followed by the address of the next hop router. In this case, all traffic not destined for networks 10.0.50.0/24 and 10.0.40.0/24 will be forwarded to 10.0.40.1, interface S0 on Router A. The default route also appears in our routing tables as both the gateway of last result and as a static route. In this scenario, Router A would still need a routing table entry that defines how to reach network 10.0.50.0/24.

Default routes are commonly used when you are routing public IP addresses to the Internet. If you didn’t define a default route, you would literally need to define a next hop address for every network on the Internet!

Monitoring IGRP

Information about IGRP messages can be obtained with the debug ip igrp command. Unlike RIP, the command requires additional information. Two types of debugging information are available for IGRP – information about IGRP events, and information about IGRP transactions. The debug ip igrp events command provides summary information about the IGRP updates being sent and received, as well as the number of routes that the update contains. The debug ip igrp transaction command actually shows the routes included in the update.

RouterA#debug ip igrp events IGRP event debugging is on 23:18:27: IGRP: received update from 10.0.20.2 on Serial0 23:18:27: IGRP: Update contains 1 interior, 0 system, and 0 exterior routes. 23:18:27: IGRP: Total routes in update: 1 23:19:24: IGRP: sending update to 255.255.255.255 via Ethernet0 (10.0.10.1) 23:19:24: IGRP: Update contains 2 interior, 0 system, and 0 exterior routes. 23:19:24: IGRP: Total routes in update: 2 RouterA#no debug ip igrp events IGRP event debugging is off RouterA#debug ip igrp transactions IGRP protocol debugging is on 23:37:20: IGRP: sending update to 255.255.255.255 via Ethernet0 (10.0.10.1) 23:37:20: subnet 10.0.30.0, metric=8576 23:37:20: subnet 10.0.20.0, metric=8476 23:37:20: IGRP: sending update to 255.255.255.255 via Serial0 (10.0.20.1) 23:37:20: subnet 10.0.30.0, metric=1100 23:38:39: IGRP: received update from 10.0.20.2 on Serial0 23:38:39: subnet 10.0.30.0, metric 8576 (neighbor 1100) RouterA#no debug ip igrp transactions IGRP protocol debugging is off

To get a quick overview on the status of the IP routing protocols running on your system, use the show ip protocols command. Notice that for Router A, we are presented with information about both of our configured protocols, RIP and IGRP.

RouterA#sh ip protocols Routing Protocol is "rip" Sending updates every 30 seconds, next due in 6 seconds Invalid after 180 seconds, hold down 180, flushed after 240 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is Redistributing: rip Default version control: send version 1, receive any version Interface Send Recv Key-chain Ethernet0 1 1 2 Serial0 1 1 2 Routing for Networks: 10.0.0.0 Routing Information Sources: Gateway Distance Last Update 10.0.20.2 120 00:00:06 Distance: (default is 120) Routing Protocol is "igrp 100" Sending updates every 90 seconds, next due in 33 seconds Invalid after 270 seconds, hold down 280, flushed after 630 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is Default networks flagged in outgoing updates Default networks accepted from incoming updates IGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0 IGRP maximum hopcount 100 IGRP maximum metric variance 1 Redistributing: igrp 100 Routing for Networks: 10.0.0.0 Routing Information Sources: Gateway Distance Last Update 10.0.20.2 100 00:01:07 Distance: (default is 100)

Configuring IGRP

The configuration of IGRP is only slightly different than that of RIP. The major difference is that IGRP routers are made part of what is known as an autonomous system (AS), a grouping that defines routers that should exchange routing tables. For example, if a router is made part of AS 100, it will only exchange IGRP routing information with other routers that are part of IGRP AS 100. Many IGRP autonomous systems can be defined within an internetwork, allowing you a more granular level of control over which routers exchange routing table information with one another.

Similar to RIP, you must also specify the networks to be included in IGRP updates. In this configuration, we are going to add IGRP AS 100 to our existing RIP network. This will also help to show what happens when two routing protocols are used on the same network. To review the network, look back at Figure 16. To add IGRP routing, use the router igrp command, followed by the autonomous system number.

RouterA#config t Enter configuration commands, one per line. End with CNTL/Z. RouterA(config)#router igrp 100 RouterA(config-router)#network 10.0.0.0

Of course, IGRP also needs to be enabled on Router B:

RouterB#config t Enter configuration commands, one per line. End with CNTL/Z. RouterB(config)#router igrp 100 RouterB(config-router)#network 10.0.0.0

A look at the routing table on Router A shows that that network 10.0.30.0 has been added, but via IGRP instead of RIP.

RouterA#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is not set 10.0.0.0/24 is subnetted, 3 subnets C 10.0.10.0 is directly connected, Ethernet0 I 10.0.30.0 [100/8576] via 10.0.20.2, 00:00:01, Serial0 C 10.0.20.0 is directly connected, Serial0

Notice that the listing for network 10.0.30.0 begins with an I, which designates that the route was found using IGRP. The RIP route is no longer available. How does this happen? This is due to that fact that IGRP has a lower administrative distance than RIP. In cases where a route is found by a protocol with a lower administrative distance, the routing table will only show the more trustworthy route. In this case, both RIP and IGRP are announcing the same route, but IGRP’s administrative distance of 100 beats RIP’s administrative distance of 120. The administrative distance and composite metric are both listed in the entry as well – [100/8576], where 8576 is the composite metric.

Like RIP, IGRP is also capable of load balancing over up to 6 links, including links with uneven costs.

Interior Gateway Routing Protocol

The Interior Gateway Routing Protocol (IGRP) is another distance vector protocol commonly used on Cisco networks. Developed by Cisco, IGRP is proprietary and provides a number of advantages over RIP on a network comprised of Cisco routers. Firstly, the maximum hop count allowed by IGRP is much greater than RIP – up to 255 hops are supported, although by default IGRP is set to allow only 100. Secondly, where RIP uses only the very basic metric of hop count to make routing decisions, IGRP actually supports a variety of metrics including bandwidth, delay, reliability, load, and MTU. The default metrics used by IGRP are bandwidth and delay.

The metrics used by IGRP almost immediately make it a better choice routing protocol than RIP, since decisions can be made based on the most efficient path to a network rather than the one with the fewest hops. IGRP uses what is known as the composite metric in determining the best path to a network. The composite metric is actually a calculation that takes into account both the minimum bandwidth between a router and a destination, and the delay value of an interface. While you don’t actually need to know how the composite metric is calculated, I think it’s still worth knowing where the numbers come from. Ultimately, the path with the lowest composite metric will be used by IGRP. To view the bandwidth and delay numbers used in the calculation of the composite metric, use the show interface command followed by the interface that the update is received on.

RouterA#show int s0 Serial0 is up, line protocol is up Hardware is HD64570 Description: WAN link Toronto-Montreal Internet address is 10.0.20.1/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255

Like RIP, IGRP routers also periodically broadcast their routing tables to exchange information with neighboring routers. The intervals involved in the exchanges are:

Route Update Timer. The route update timer controls how often a router will send out routing table updates. An IGRP router will send out updates every 90 seconds by default.

Route Invalid Timer. The route invalid timer specifies the amount of time that will pass before an IGRP router will mark a network as unavailable. By default this is set to three times the update timer, or 270 seconds.

Route Holddown Timer. The route holddown timer specifies the length of the holddown timer that will be used when IGRP receives information about an unreachable routing table entry. The default holddown timer for IGRP is 3 times the update interval plus 10 seconds, or 280 seconds total.

Route Flush Timer. The amount of time that will pass before IGRP completely removes an entry from the routing table. By default, this is set to seven times the update interval, or 630 seconds.

Monitoring RIP

Once RIP is up and running, it can largely be left alone. However, there are a number of commands that you should be familiar with in order to gain information about the status of RIP, or for troubleshooting purposes.

Of these commands, the most basic and useful is the show ip protocols command. The command will provide you with information about the interfaces on which RIP is configured, the sources of routing information, and the timer values configured.

RouterA#sh ip protocols Routing Protocol is "rip" Sending updates every 30 seconds, next due in 26 seconds Invalid after 180 seconds, hold down 180, flushed after 240 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is Redistributing: rip Default version control: send version 1, receive any version Interface Send Recv Key-chain Ethernet0 1 1 2 Serial0 1 1 2 Routing for Networks: 10.0.0.0 Routing Information Sources: Gateway Distance Last Update 10.0.20.2 120 00:00:19 Distance: (default is 120)

Notice that this router is receiving updates from address 10.0.20.2, the near interface on Router B.

In order to gain more information about the actual contents of the RIP traffic moving between systems, use the debug ip rip command. This particular command is like a toggle switch – debugging information that shows the contents of RIP updates sent and received will continue to appear on-screen until you turn it off with the no debug ip rip command.

RouterA#debug ip rip RIP protocol debugging is on 22:48:34: RIP: received v1 update from 10.0.20.2 on Serial0 22:48:34: 10.0.30.0 in 1 hops 22:48:38: RIP: sending v1 update to 255.255.255.255 via Ethernet0 (10.0.10.1) 22:48:38: subnet 10.0.20.0, metric 1 22:48:38: RIP: sending v1 update to 255.255.255.255 via Serial0 (10.0.20.1) 22:48:38: subnet 10.0.20.0, metric 1 RouterA#no debug ip rip

Note that the debug ip rip command shows the RIP updates both sent and received on a particular interface, along with associated subnet and metric information. Remember than a metric of 16 suggests an unreachable network in RIP.

Although you don’t need to know how to do this for the exam, it’s always nice to know how to change the default timers used by a protocol. The command to do so is timers basic, and is issued from the routing protocol configuration level. One important note here – if you do decide to change the timers on one router, you should also change the timers on every router. Otherwise, you’ll be dealing with one very unpredictable network potentially susceptible to routing loops.

RouterA(config)#router rip RouterA(config-router)#timers basic ? <0-4294967295> Interval between updates RouterA(config-router)#timers basic 30 ? <1-4294967295> Invalid RouterA(config-router)#timers basic 30 180 ? <0-4294967295> Holddown RouterA(config-router)#timers basic 30 180 180 ? <1-4294967295> Flush RouterA(config-router)#timers basic 30 180 180 240

I used the help function to walk through the timers basic command step by step to show you the order of the entries – update, invalid, holddown, and flush. Ultimately, the same command can be used to set IGRP timers.

Configuring RIP

In this section we’re going to configure a simple network with two routers to run RIP. Our network in consists of three subnets, 10.0.10.0/24, 10.0.20.0/24, and 10.0.30.0/24, as shown in the figure below. Our goal is to ultimately have Router A learn about network 10.0.30.0 from Router B, and Router B learn about network 10.0.10.0 from Router A using RIP.

Figure: Network configuration for distance vector protocol configuration examples.

If you’re trying to configure a router to use RIP to exchange routing table information, a first important step is to remove any static routes that you may have defined. Remember those administrative distances that we looked at earlier? If you have a static route defined on Router A that provides information on how to get to network 10.0.30.0, any information that Router A receives about network 10.0.30.0 via RIP will be ignored. A static route has an administrative distance of 1, while RIP’s administrative distance is 120. When a route with a higher administrative distance is received, it is ignored, since a more trustworthy routing table entry already exists.

The command to turn on RIP routing is simple – from global configuration mode, simply issue the command router rip, as shown below.

RouterA(config)#router rip RouterA(config-router)#

Notice how the prompt changes. At the most basic level, the router rip command makes this router capable of sending and receiving RIP updates. However, in order for this router to send out any information of use, we have to tell it which network(s) to advertise. In this case, the network we want to advertise is 10.0.0.0. You don’t need to specify either the subnet mask or specific subnet addresses – because RIP is classful, it will automatically assume that you meant all networks starting with 10. In order to make RIP announce all of the 10.0.0.0 subnets, enter the network 10.0.0.0 command, as shown below.

RouterA(config-router)#network 10.0.0.0 RouterA(config-router)#

That’s literally all it takes to set up RIP. Of course, we’ll also need RIP configured on Router B, which involves following the same steps.

RouterB(config)#router rip RouterB(config-router)#network 10.0.0.0

In order to confirm that RIP is properly exchanging information between our routers, let’s take a look at the routing tables on Router A.

RouterA#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is not set 10.0.0.0/24 is subnetted, 3 subnets C 10.0.10.0 is directly connected, Ethernet0 R 10.0.30.0 [120/1] via 10.0.20.2, 00:00:22, Serial0 C 10.0.20.0 is directly connected, Serial0

Notice in the routing table above that Router A learned about network 10.0.30.0 from RIP, as designated by the R at the beginning of the entry. The administrative distance is 120, and the number of hops to reach the network is 1, as designated by the entry [120/1].

Finally, the next-hop address is 10.0.20.2, which is accessible via interface Serial0.
An easy way to test whether RIP is working on both routers is a simple ping. If Router A can successfully ping IP address 10.0.30.1, it means that Router B also has a route (learned from RIP) back to network 10.0.10.0.

RouterA#ping 10.0.30.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.0.30.1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 32/38/48 ms

Remember that many routing protocols are also able to load-balance across multiple paths. RIP can load balance traffic across up to 6 paths, as long as the hop counts to the network in question are equal.

Routing Information Protocol (RIP)

The Routing Information Protocol (RIP) is a simple distance-vector protocol. In order to avoid confusion, you should be aware that two versions of RIP exist – RIP version 1 (RIP), and RIP version 2 (RIPv2). For the purpose of the CCNA exam, you need to be familiar with RIP version 1, which is what we’ll look at in this section. RIPv2 will be looked at a little later in the chapter.

The first thing that needs to be made clear is that RIP is a classful protocol. What that means is that RIP will always assume the class of an address according to the standard Class A, B, and C designations. Ultimately, this means that RIP is expecting that every single host in a network is using the same subnet mask. This does not mean that RIP won’t work on a subnetted network; only that all of the subnet masks are assumed to be the same. Techniques like VLSM won’t work with RIP, mainly because when RIP sends out its routing table updates, it doesn’t include any subnet mask information.
Recall that RIP uses hop count as its metric in determining the best route to a network. Remember that RIP will always take the path with the fewest hops, regardless of factors like bandwidth, delay, or otherwise.

The maximum diameter of a RIP network is 15 hops. That means that a maximum of 15 routers can be traversed between a source and destination network before a network is considered unreachable. At the 16th hop (which RIP considers to be “infinity”), the TTL reaches 0, and a packet is discarded. Obviously this makes RIP a poor choice for very large internetworks.

RIP is also incredibly chatty. By default, a RIP router will broadcast out its complete routing table every 30 seconds, regardless of whether anything has changed. That’s not terribly efficient, and causes a great deal of unnecessary traffic. Remember that broadcasts go to all hosts in a broadcast domain, meaning that even regular computers will have to process RIP packets to some degree before discarding them. RIP may not be pretty, but it is simple.

There are a few different timers that you should be familiar with on a RIP network. There include:

Route Update Timer. The route update timer controls how often a router will broadcast routing table updates. As mentioned, a RIP router will broadcast its complete routing table every 30 seconds by default.

Route Timeout Timer. The route timeout timer specifies the amount of time that will pass before a router will mark a network as unavailable, and is set to three times the update interval (180 seconds) by default. For example, if a router doesn’t hear about network 172.16.0.0 from any other router for 180 seconds, it will mark the route as invalid. After marking a route as invalid, the information will be sent to other routers via a triggered update.

Route Holddown Timer. The route holddown timer specifies the length of the holddown timer that will be used when RIP receives information about an unreachable routing table entry. The default holddown timer is 180 seconds.

Route Flush Timer. After marking a route as invalid, a RIP router will not immediately remove the route from its routing table. Instead, it will wait until the flush timer (sometimes called the garbage collection interval) has expired. This gives the router time to let other routers know about the invalid route before removing the entry from its routing table. The default flush timer is 240 seconds.

While RIP may not be the most efficient or effective routing protocol for use on large networks, it still does the job. A big reason why RIP is so popular is because of how easy it is to set up. With as few as two commands, you can have your router fully configured for RIP.

Hybrid Routing Protocols

Some protocols can’t be so clearly defined as either distance-vector or link state. A great example is Cisco’s Enhanced IGRP (EIGRP), which is more accurately defined as a hybrid between the two. While distance vector protocols typically rely on the broadcast of complete routing tables, EIGRP instead only sends out specific updates when the metric to a route changes. Like link state protocols, EIGRP also maintains a database of neighboring routers and the network topology.