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OK, so in this task, we need to enable SNMP on the routers here's router 1,

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I'll go into global configuration mode and use the command SNMP server community to enable SNMP.

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We've been told to use public and private as the community strings, in the real world

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you wouldn't want to do that, in the real world

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you want to use something a lot more secure than public and private

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but because this is the lab and we simply want to get used to using SNMP, I'll configure SNMP with those

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two community strings.

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So show run shows us

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those two SNMP community strings, as configured on router 1, on router 2 we'll do something

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very similar.

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So on router 2 SNMP server community public read-only, 

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SNMP server of a community private is going to be read write.

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So we've got our two community string's configured on both routers.

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That's essentially all we need to do on the routers and now on the PC

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we should be able to use the MIB browser to interrogate the routers.

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So on the PC, on the desktop MIB browser, I'll put in the IP address of the first router.

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The IP addresses have been configured on these devices.

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So show IP interface brief on router

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1 shows us the IP address of router 1.

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So 10.1.1.1, 

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I'm going to click on advanced

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read community is going to be public, write community is going to be private.

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We've been told to use SNMP version 3 per these instructions, so I'm going to click, OK, and

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then hopefully I should be able to browse through the MIB tree until I find

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system

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sysname. So we've been told to get the hostname of router 1 and router 2 as the first task we're going

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to be using an SNMP get, to do that, click go

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should allow us to get the hostname of the router

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and as you can see here, the router name is R1.

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If I do something similar with router 2, click go and notice the router name is router 2 so it was as simple

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as that to get the hostname of the routers, now we need to view the interfaces on router 1.

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So under interfaces

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and I need to do that in router 1 you could do something similar on router 2 if you wanted to.

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Let's have a look at the interface index, there are interface numbers, description, 

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notice there are the interfaces on the router.

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We can confirm that by using show IP interface brief on the router again.

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So show IP interface brief, 

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we've got gigabit 00.01.02 loopback and VLAN 1

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and there you go.

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It's as simple as that to interrogate a router using SNMP and to get back information about the router.

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So what are the interface types? So I have type click go, we can see copper, gigabit, Ethernet, 

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loopback and VLAN as the interface types.

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You could also look at other information, such as the maximum transmission unit, the speed

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of the interfaces, physical addresses, so the Mac addresses.

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So on the router show, interface Gigabit 00

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notice the Mac address of Gigabit 00, 

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which is this interface over here. So SNMP allows a management station to get a lot of information about

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a device such as the status of interfaces.

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So that's administrative statuses, here's operational statuses.

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Because we shut interfaces down, they're showing as both administratively down and operationally down,

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once again, the only interfaces enabled on the router are gigabit 00

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and the loopback interfaces, other interfaces are administratively down and we can see that

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through this interface.

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So let's have a look at the routing table of router 1.

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So IP, IP routing table, let's look at the route destination, there are the routes in the routing table.

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We can confirm that again

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by looking at router 1s CLI, so show IP route.

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There's network quadruple one, we can see that here,

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quadruple 2 shown here, 

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10.1.1.0, 10.1.1.1, we can see that here and we can see a default route

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which is pointing to router 2, we can see default route information in the routing table through

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SNMP.

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So, again, it was as simple as that to get routing information via SNMP.

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OK, so the next thing we need to get is the OSPF area on router 1, as well as the OSPF router

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ID and OSPF neighbors.

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So back in the MIB browser, go to OSPF.

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We can get the OSPF router ID, there it is, we can get, as an example, the version of OSPF used which

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is version 2, we can get the administrative status of OSPF.

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Back on the router, show OSPF

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we can see that OSPF is enabled.

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Here's the router ID, this is using OSPF version 2 because it's OSPF for IP version 4.

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We can also get the OSPF area ID, notice its area zero, again on the router

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notice the backbone area, area zero has been enabled in OSPF you can represent it this way or you can

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represent it this way.

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In this example, authentication hasn't been enabled in OSPF.

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We could also look at

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the links state database see things such as the router IDs in the link state database,

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notice we see those too.

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So show IP OSPF database, they are LSA type 1 OSPF

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entries and here's LSA type 2

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and we can see that through SNMP.

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What about the neighbor table, so 

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neighbor IP address on router 1 is router 2. On the router show IP OSPF neighbor

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we can see that router 2 is a neighbor.

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If we change this to router 2, 

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we can see that router 1 is a neighbor to router 2 and we can see

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the router ID of router 1 requiring router 2 at this point, it has a router ID neighbor of 1

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111.

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So on router 2

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show IP OSPF neighbor, notice there's the neighbor router ID and the IP address of the neighbor as seen on

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router 2 again.

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There's the IP address as shown here through SNMP router ID is this, as we can see here on router 2.

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We can look at the OSPF priority.

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So notice the neighbor has a priority of 100, on router 2

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we can see that router 1 has that priority configured and on router 1 show run shows us

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that the priority was configured on the Gigabit00 interface.

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So a lot of information can be gleaned through SNMP.

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I've completed all the read-only tasks.

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Let's change the name of R1 to router 1, so here's router 1 notice

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the router name is R1.

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What we want to do now, however, is change the system name at the moment, it's R1 but we want

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to change that by using a set

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and in this case, it's an octet string.

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So let's change the name to R1

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click go, we're told that the router name is changed on the router

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we can confirm that the router name has changed.

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So if I go back to get there's the router name, I could change it back to R1

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click OK, click go router name has changed, we can confirm that again through the console of

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the router. So I'll change that back to get, then to set

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and set it back to router 1 per our instructions and notice on the router we see that the name

111
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is router 1.

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So I'm happy with that.

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I've completed these tasks and shown you a bit more.

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How did you get on, were you able to complete these tasks?

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Now, as an extra I'm going to set

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packet tracer to simulation mode

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and then I'm going to use get to get the router name from router 1 and click go.

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So notice an SNMP packet is sent to the router.

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SNMP port is port 161

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this is a UDP packet, source

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IP address is 10.1.1.200, which is the PC destination is the router.

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We can see the outbound PDU here so we can see lots of information, such as the source, Mac address,

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destination Mac address.

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We can see source IP the PC, the destination is the router, but the important information is here.

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SNMP uses UDP Port 161 as both the source and destination Port number.

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I'll click capture forward packet goes to the switch and then onto the router.

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So let's have a look at the packet inbound PDU looks like this.

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We're not seeing a lot of SNMP information.

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In packet tracer we can see that the version of SNMP is version 3, we can see that the community is set to

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public.

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On the packet that goes back to the PC notice the source is the router destination is the PC.

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We can see version 3 community is public.

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Let's capture forward to that.

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It's the PC

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and on the PC, we've received that

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SNMP packet, we're not seeing a lot of detail through packet tracer here, it's not showing us the

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actual information that's returned, such as the router hostname

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but if you were using a proper Wireshark capture, you'd be able to see more information.

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But what I want to point out is notice the source and destination port number is 161, 

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Protocol used is the UDP.

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What I like about packet tracer here is it's shown us clearly how SNMP works.

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It's very simple to configure SNMP and then browse the MIBS

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on the devices using S&NMP and retrieve information, as well as configure the devices through SNMP.