Rip and OSPF assignment (RIP ба OSPF дасгал ажил)

Departamento de Informática
Escola de Engenharia
Universidade do Minho
_________________________________________________________________________Tecnologias e Protocolos de Rede, 2015/2016
Tecnologias e Protocolos de Rede [2015/2016]
MIEI/MERSTel
Laboratory Work TP1: Routing [Part #1]
Objectives
• Develop initial/basic experiences in the configuration of OSPF and RIP routing
protocols.
• Contact with real systems for programming/configuration of network equipment
• Use of network emulation tools, e.g. CORE (Common Open Research Emulator)
• Development of research skills and (self)learning processes related with the
configuration of routing protocols.
Report
• All working groups will prepare a report describing the answers/
commands/tasks/analysis made in the context of this laboratory work.
• The definition of the report structure and included contents is the responsibility of the
working groups.
• The reports will be evaluated taking into account i) the correction/technical quality of the
solutions/settings/answers/explanations made regarding the proposed tasks/challenges
and ii) clarity/organization/quality of the submitted report.
• The reports should be submitted by the deadline set by the teacher.
____________________________________________________________________________
In the context of this work, it is expected that students perform the adequate research for the
addressed topics. The following references/links are merely illustrative and should be
complemented with other references deemed relevant.
• http://www.nrl.navy.mil/itd/ncs/products/core
• http://downloads.pf.itd.nrl.navy.mil/core/vmware-image/
• Several manuals/documentation regarding the configuration of routing protocols in
CISCO equipment can be searched on the net, with many available in
http://www.cisco.com/........
[note: In the CORE emulator the routing processes are based on the Quagga
framework (http://www.nongnu.org/quagga/). However, most of the configuration
commands are quite similar to the ones commonly used in CISCO IOSs]
____________________________________________________________________________
Tasks
- Familiarization with the emulator CORE (Common Open Research Emulator)
http://www.nrl.navy.mil/itd/ncs/products/core

- Installation of the virtual machine of vcore 4.6 (available for VMware or VirtualBox)
http://downloads.pf.itd.nrl.navy.mil/core/vmware-image/
A) RIP (Routing Information Protocol) Protocol
1. Define a network topology involving multiple routers, interconnecting core links and end-
user networks. The topology should include at least two distinct redundancy scenarios: i)
in the view of at least one of the routers there are at least two alternatives paths with the
same minimum cost to a given network (e.g. “router x” to reach the network “rede A”)
and ii) in view of at least one of the routers there are at least two paths with different
costs to reach one or more networks (e.g. “router y” to reach the network “rede B”).
Figure 1 shows an illustrative topology defined in this context.
Figure 1 – Illustrative example of a topology with multiple links and routers.
2. Analyse and comment on the IP address configuration of the routers/hosts interfaces that
was assigned by CORE.
3. Configure all routers of the topology to use the RIP protocol for routing dissemination of
all interconnection and end-user networks.
4. Activate the defined topology and undertake connectivity tests (e.g ping etc.) between the
various routers/networks and check the used routes.
5. i) View and analyze the routing tables that were established by the routers of the core
network.
[note: a specific routing table considered relevant for this purpose should be
selected and explained in detail]
ii) View and analyze the routing tables of the hosts of the user-networks.
[note: explain in detail a specific routing table of one of the hosts]

6. Assume that the administrator wants to change the time interval by which are generated
the RIP updates messages. What command could be used for this purpose?
7. Through the configuration console of the routers shutdown one (or more) interconnection
links/interfaces in order to originate two distinct scenarios:
i) Even with the disabled interface(s) all routers/networks of the topology can
maintain connectivity
ii) Some of the routers/networks have no available paths to reach other routers/
networks of the topology.
For each of the scenarios described above explain the observed modifications in the
routing tables of the routers and comment on the time taken to propagate the routing
information.
[note: for each one of the above situations, a specific routing table considered relevant
for this purpose should be also selected and explained in detail]
8. Configure one of the routers of the topology so that the traffic that it transmits to a
particular destination network not cross the path with the smaller number of hops, but
another alternative path (i.e. in the example in Figure 1, to send traffic to “rede B” the
“router y” will use the path that passes through the “router x. For all other destinations the
path with the least number of hops will continue to be the chosen one).
[hint: in the theoretical lectures a specific command that solves this issue was mentioned]
9. Assume that your network will be connected to another external network via router x (see
Figure 2). Present and explain the configuration command(s) that will be used to assure
that all traffic directed to external networks leave the domain using the router x.
Figura 2 – Router x as the exit point for all the external traffic.

B) OSPF (Open Shortest Path First) Protocol
10. In the defined topology configure some of the links with a bandwidth of 10 Mbps and
others with a bandwidth 100 Mbps.
11. Configure all routers of topology to use the OSPF protocol for routing dissemination of all
interconnection and end-user networks. All routers should integrate a single OSPF area
(e.g. area 0).
12. Activate the defined topology and undertake connectivity tests (e.g ping etc.) between the
various routers/networks and check the used routes.
13. Explain the OSPF configuration settings that were installed in the routers of the network.
14. View and analyze the routing tables that were established by the routers of the core
network.
[note: a specific routing table considered relevant for this purpose should be
15. What command allows you to check which OSPF costs are associated with the various
interfaces of a router? Analyze and comment the costs that were assigned to the links of
the network topology.
16. Change the OSPF costs of the router interfaces so that links having bandwidths of 10
Mbps are assigned with a cost value of "10" and 100 Mbps links have OSPF cost values
of "1".
17. In view of the change made in task 16 observe and analyze the changes that were made
in the routing tables of the routers.
[note: a specific routing table considered relevant for this purpose should also be
18. Taking into account the previous experiences explain how should be configured the
OSPF costs of the routers interfaces of a network topology.
19. In the previous experiments it can be observed that sometimes for the same destination
multiple OSPF equal cost routes exist. (note: if you have not seen any of these cases
proceed to configuration changes that create equal cost routes to a destination).
Investigate and explain different types of approaches that routers may use to deal with
these situations. Also mention and explain the advantages/disadvantages of each one.
20. Suppose that the network routers of the defined topology have simultaneously the RIP
and OSPF protocols activated. In this case, which routes would be chosen? Replicate
this scenario in your network topology. (Note: if exist, delete all RIP/OSPF route
redistribution commands form the routers configurations).

University of Minho
Technologies and Network Protocols
Routing
Basic experiences with RIP and OSPF routing protocols
João Dias
Khunbish Nyamsuren
Simão Dias

Contents
1 Introdução 3
2 Used Software and Method 3
3 RIP 4
3.1 Question 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2 Question 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.3 Question 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.4 Question 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.5 Question 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.6 Question 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.7 Question 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.8 Question 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.9 Question 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
List of Figures
1 Topology 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Enabling RIP protocol . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Connection path between R1 and PC-C2 . . . . . . . . . . . . . . . . . . 10
4 Confirmation that both of R2’s interfaces are shutdown. . . . . . . . . 11
5 Traceroute from R5 to the external host . . . . . . . . . . . . . . . . 12
8 Ping from PC-B1 to the external host . . . . . . . . . . . . . . . . . . 13
9 Ping from PC-C1 to the external host . . . . . . . . . . . . . . . . . . 14

Abstract
In dynamic routing environments, IP routing information is propagated using rout-
ing protocols. Nowadays, the most common protocols found in intranets are Routing
Information Protocol and Open Shortest Path First. With the assistance of network
emulation software and with a set of predefined questions, we will go more in depth
on the programming/configuration of network equipment that operates under the pre-
viously mentioned protocols. After this project we were able to reach a better
understanding of this protocols and of the process that is required to accomplish a
fully operating network.
2

Introdução
A computer network is a network with two or more interconnected devices in such way
that they are able to exchange hardware or software resources. A network is composed
of Nodes (which represents the devices) and links between them (which may be other
networks).
Nowadays we find networks at the most various places with the most diverse devices,
this networks can be defined by their size, topology, physical layout and protocols.
In this project we focus on the protocols, specifically two of the most common intranet
protocols: RIP (Routing Information Protocol) and OSPF(Open Shortest Path First).
Network protocols are responsible for the routing process, specifying how devices
communicate with each other by spreading information that enables them to select the
best routes between two nodes of a network.
This document will be divided in two parts, one for RIP and another for OSPF. Each
part will answer a series of questions as well as showing the used procedure to obtain
said answers.
Used Software and Method
To be able to answer the provided questions, the workgroup used Common Open Research
Emulator (CORE). Running under a virtual machine, this piece of software offers a
graphical interface to build emulated networks.
It allows us to represent different devices such as hosts, routers, switches and links
between them. Once the emulation is launched, a virtual machine will run to represent
each node from which we have access to the bash shell where we can run the already
known commands such as pings, traceroutes or even enter in the configuration mode.
Most importantly, it allows us to swiftly change between protocols.
3

RIP
The Routing Information Protocol is a distance-vector protocol, therefore he is only
aware of his neighbors and calculates the best path with this knowledge.
Question 1
Define a network topology involving multiple routers, interconnecting core links and
end-user networks. The topology should include at least two distinct redundancy sce-
narios:
1. In the view of at least one of the routers there are at least two alternatives
paths with the same minimum cost to a given network (e.g. “router x” to reach the
network “rede A”)
2. in view of at least one of the routers there are at least two paths with different
costs to reach one or more networks (e.g. “router y” to reach the network “rede
B”). Figure 1 shows an illustrative topology defined in this context.)
Respecting this restrictions we developed the following topology:
Figure 1: Topology 1
Item 1 Proof
If we take in consideration R2, it has two possible ways to reach network 10.0.4.0/24
with the same Hop cost: R2 -> R3 -> R5 or R2 -> R1 -> R4.
Considering the Hop cost is the same, the protocol randomly chose to go through
the first mentioned path. In the red line below, we can see that R2 can reach
10.0.4.0/24 with 3 hops via interface eth1 wich leades to R3.
4

R>* 10.0.0.0/24 [120/2] via 10.0.1.1, eth0, 00:07:42
C>* 10.0.1.0/24 is directly connected, eth0
R>* 10.0.2.0/24 [120/2] via 10.0.1.1, eth0, 00:07:42
R>* 10.0.4.0/24 [120/3] via 10.0.3.2, eth1, 00:07:41
R>* 10.0.5.0/24 [120/2] via 10.0.3.2, eth1, 00:07:41
R>* 10.0.6.0/24 [120/2] via 10.0.3.2, eth1, 00:07:41
C>* 127.0.0.0/8 is directly connected, lo
Now if we shutdown R2’s eth1 interface, R2’s routing table is forced to change
and we can see that the second alternative path is selected. In the red line
below, we can see that R2 can reach 10.0.4.0/24 also with 3 hops via interface
eth0 wich leads to R1.
R>* 10.0.0.0/24 [120/2] via 10.0.1.1, eth0, 00:01:10
R>* 10.0.2.0/24 [120/2] via 10.0.1.1, eth0, 00:01:10
R>* 10.0.3.0/24 [120/5] via 10.0.1.1, eth0, 00:00:43
R>* 10.0.4.0/24 [120/3] via 10.0.1.1, eth0, 00:00:43
R>* 10.0.5.0/24 [120/4] via 10.0.1.1, eth0, 00:00:43
R>* 10.0.6.0/24 [120/5] via 10.0.1.1, eth0, 00:00:43
Item 2 Proof
If we take in consideration R2 again, it has two possible ways to reach network
10.0.2.0/24 with different Hop cost: R2 -> R1 or R2 -> R3 -> R5 -> R4.
In the red line below, we can see that R2 can reach 10.0.2.0/24 with 2 hops via
eth0 wich leads to R1.
R>* 10.0.0.0/24 [120/2] via 10.0.1.1, eth0, 00:07:42
R>* 10.0.2.0/24 [120/2] via 10.0.1.1, eth0, 00:07:42
R>* 10.0.4.0/24 [120/3] via 10.0.3.2, eth1, 00:07:41
R>* 10.0.5.0/24 [120/2] via 10.0.3.2, eth1, 00:07:41
R>* 10.0.6.0/24 [120/2] via 10.0.3.2, eth1, 00:07:41
INSERT IP ROUTE WITH R2 ETH0 SHUTDOWN
Question 2
Analyse and comment on the IP address configuration of the routers/hosts interfaces
that was assigned by CORE.
5

Core emulater auto-assigned 10.X.Y.0/24 ip adresses. This is the private ip pool
and RFC 1918 standard. Class C addresses use the last octet to identify each host
which means each network can have up to 254 hosts. Class C addresses and are commonly
used for small to mid-size businesses. Considering the size of this project, using
class C seems like a good fit.
Question 3
Configure all routers of the topology to use the RIP protocol for routing dissemina-
tion of all interconnection and end-user networks.
Core makes protocol interchange easy, to accomplish this, all we have to do is to
select each different device, right-click -> Services and make sure RIP protocol is
enabled as showed in the following figure:
Figure 2: Enabling RIP protocol
6

Question 4
Activate the defined topology and undertake connectivity tests (e.g ping etc.) be-
tween the various routers/networks and check the used routes.
To test the network connectivity we chose some devices that combined use the whole
network. If this nodes are connected, it means that the middle networks also have
connectivity between each other. We used the ping command to test the connectivity on
the following devices:
• PC-B1 -> PC-C1
asdasd
• PC-B1 -> PC-C2
• PC-B2 -> PC-C1
• PC-B2 -> PC-C2
Considering that the hosts communicate within the shortest path in terms of
hop metric, we tested separately the connectivity between the unused paths.
• R1 -> R5
• R5 -> B3
Question 5
1. View and analyze the routing tables that were established by the routers of the
core network. [note: a specific routing table considered relevant for this
purpose should be selected and explained in detail]
We considered R3 as a good test subject for this question. By using the command
show ip route in the routers terminal, we obtain it’s routing table:
R>* 10.0.0.0/24 [120/3] via 10.0.3.1, eth0, 00:05:32
R>* 10.0.1.0/24 [120/2] via 10.0.3.1, eth0, 00:05:34
R>* 10.0.2.0/24 [120/3] via 10.0.3.1, eth0, 00:05:32
R>* 10.0.4.0/24 [120/2] via 10.0.5.1, eth1, 00:05:34
7

Route
Source
Destination
Network
Administrative
Distance and Hop
metric
Next-hop Outgoing
Interface
Route
Times-
tamp
R>* 10.0.X.Y [120/H] 10.0.A.B ethZ HH:MM:SS
Route source: Identifies how the route was learned, in this case R stands for
RIP.
Destination Network: Identifies the address of the remote network.
Administrative Distance: 120 by default, identifies the trustworthiness of the
route source.
Hop Metric (H): Identifies the value assigned to reach the remote network. lower
values indicate preferred routes.
Outgoing Interface: Identifies the exit interface to use to forward a packet
toward the final destination.
Route Timestamp: Identifies from when the route was last heard.
Route Source Destination Network Outgoing Interface
C>* 10.0.X.Y/24 ethZ
If the Route Source is a C it means the Source is directly connected to the des-
tination network through the Outgoing Interface.
2. View and analyze the routing tables of the hosts of the user-networks. [note:
explain in detail a specific routing table of one of the hosts]
On the hosts side the routing table differ a little bit. To exemplify its contents
we run the command route -n on the Host PC-C2 and got the following result:
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.0.6.1 0.0.0.0 UG 0 0 0 eth0
10.0.6.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
Destination: Identifies the address off a remote network.
Gateway: Identifies the gateway Address.
Genmask: The netmask for the destination net; 255.255.255.255 for a host desti-
nation and 0.0.0.0 for the default route.
Flags: U stands for (route is up) and G for (use gateway).
Metric: The distance to the target . In this case 0 because the host is directly
8

connected to the router.
Ref: Number of references to this route. (Not used in the Linux kernel.)
Use: Count of lookups for the route.
Iface: Interface to which packets for this route will be sent. In this case the
host only has one interface(eth0).
This host has learned two routes: 0.0.0.0 is the default route, a default route
is used when no other routes for the destination are found in the routing table;
and 10.0.6.0 which is the local network.
Question 6
Assume that the administrator wants to change the time interval by which are generated
the RIP updates messages. What command could be used for this purpose?
To change the time interval we use the command timer basic A B C inside a Router
terminal in config mode, where A, B and C are as follows:
• A: The value in seconds to which the routing table must update (30 as default).
• B: The value in seconds to which the information times out (180 as default).
• C: The value in seconds for the garbage collection (120 as default).
Has an example of the chain of commands necessary we used R1 as test subject:
R1# configure terminal
R1(config)# router rip
R1(config-router)# timer basic 30
<5-2147483647> Routing table update timer value in second. Default is 30.
R1(config-router)# timer basic 60
<5-2147483647> Routing information timeout timer. Default is 180.
R1(config-router)# timer basic 60 360
<5-2147483647> Garbage collection timer. Default is 120.
R1(config-router)# timer basic 60 360 240
Question 7
Through the configuration console of the routers shutdown one (or more) interconnec-
tion links/interfaces in order to originate two distinct scenarios:
1. Even with the disabled interface(s) all routers/networks of the topology can
maintain connectivity
2. Some of the routers/networks have no available paths to reach other routers/net-
works of the topology.
Item 1 Proof
MISSING
9

Item 2 Proof
To cut the connection from one router with the rest of the topology we chose the router
R2. Initially, we did a path test between R1 and PC-C2 and obtained Figure 3.
Figure 3: Connection path between R1 and PC-C2
We can see that R1 chooses R2 as a path to reach PC-C2. Now, to alienate R2 we cut
both of R2’s interfaces. We do this by going to the R2 terminal, entering configuration
mode, selecting the interface we desire to change and apply the shutdown command. We
repeat this step for both of R2’s interfaces. To undo this command we can run no
shutdown.
After shutting down the interfaces we run show interface and verify that both are down
as we can see in Figure 4.
Now if we run show ip route we see that the next hop to reach the network 10.0.6.0/24
is through R4:
R1# sh ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
O - OSPF, o - OSPF6, I - IS-IS, B - BGP, A - Babel,
> - selected route, * - FIB route
R>* 10.0.4.0/24 [120/2] via 10.0.2.2, eth2, 00:02:07
R>* 10.0.5.0/24 [120/3] via 10.0.2.2, eth2, 00:00:06
R>* 10.0.6.0/24 [120/4] via 10.0.2.2, eth2, 00:00:06
Question 8
Configure one of the routers of the topology so that the traffic that it transmits
to a particular destination network not cross the path with the smaller number of
10

Figure 4: Confirmation that both of R2’s interfaces are shutdown.
hops, but another alternative path (i.e. in the example in Figure 1, to send traffic
to “rede B” the “router y” will use the path that passes through the “router x. For
all other destinations the path with the least number of hops will continue to be the
chosen one). [hint: in the theoretical lectures a specific command that solves this
issue was mentioned]
MISSING
Question 9
Assume that your network will be connected to another external network via router x
(see Figure 2). Present and explain the configuration command(s) that will be used
to assure that all traffic directed to external networks leave the domain using the
router x.
First we added an external network to the topology and after we used the command
ip route 0.0.0.0 0.0.0.0 10.0.7.2 in the R4. This command sets the gateway of last
resort to 10.0.7.2 which means all traffic that is not local will be sent to this
router. Onde the topology is set to redirect to the external networks via 10.0.7.2 we
ran default-information originate, with this we advertise the default route to the
rest of the topology. In the end we did various connectivity tests from different
routers to the external network.
11

Figure 5: Traceroute from R5 to the external host
12

Figure 8: Ping from PC-B1 to the external host
13

Figure 9: Ping from PC-C1 to the external host
14

Rip and OSPF assignment (RIP ба OSPF дасгал ажил)

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