This lab explores the MAC address table on Cisco IOS switches and routing table on Cisco IOS routers.
This lab is a guided walk through of Cisco device functions. You will explore the commands used here in much more detail as you go through the rest of the lab exercises.
Lab Topology
Lab Download
All of our lab exercises use EVE-NG as the platform for the emulation server. Download the below exercise file and import into your EVE-NG server as a project file.
Cisco IOL Images:
- Switches :: i86bi_linux_l2-adventerprisek9-high_iron.bin
- Routers :: i86bi-linux-l3-adventerprisek9-15.4.1T.bin
| 01 - Cisco Device Functions - Lab Exercise (225 downloads) |
| MD5 Hash: 9640a769892216ad86a27ab89dc84566 |
| SHA1 Hash: 2d27bdaecbb45c75745ea7fea39da1b9266908c2 |
Examining the MAC Address Table
- Log into each of the routers (R1 > R4) and verify that the connected interfaces are configured with an IP Address from the 10.10.10.0/24 network.
R1#show ip interface brief Interface IP-Address OK? Method Status Protocol Ethernet0/0 10.10.10.1 YES NVRAM up up Ethernet0/1 unassigned YES NVRAM administratively down down Ethernet0/2 unassigned YES NVRAM administratively down down Ethernet0/3 unassigned YES NVRAM administratively down down
R2#show ip interface brief Interface IP-Address OK? Method Status Protocol Ethernet0/0 10.10.10.2 YES NVRAM up up Ethernet0/1 unassigned YES NVRAM administratively down down Ethernet0/2 unassigned YES NVRAM administratively down down Ethernet0/3 unassigned YES NVRAM administratively down down
R3#show ip interface brief Interface IP-Address OK? Method Status Protocol Ethernet0/0 10.10.10.3 YES NVRAM up up Ethernet0/1 unassigned YES NVRAM administratively down down Ethernet0/2 unassigned YES NVRAM administratively down down Ethernet0/3 unassigned YES NVRAM administratively down down
R4#show ip interface brief Interface IP-Address OK? Method Status Protocol Ethernet0/0 10.10.10.4 YES NVRAM up up Ethernet0/1 unassigned YES NVRAM administratively down down Ethernet0/2 unassigned YES NVRAM administratively down down Ethernet0/3 unassigned YES NVRAM administratively down down
- Next, get the MAC Address for each of the connected interfaces and note them down in a text document, like Notepad++
R1#show interfaces e0/0 | i address Hardware is AmdP2, address is aabb.cc00.3100 (bia aabb.cc00.3100) Internet address is 10.10.10.1/24 R2#show interfaces e0/0 | i address Hardware is AmdP2, address is aabb.cc00.4100 (bia aabb.cc00.4100) Internet address is 10.10.10.2/24 R3#show interfaces e0/0 | i address Hardware is AmdP2, address is aabb.cc00.5100 (bia aabb.cc00.5100) Internet address is 10.10.10.3/24 R4#show interfaces e0/0 | i address Hardware is AmdP2, address is aabb.cc00.6100 (bia aabb.cc00.6100) Internet address is 10.10.10.4/24
Note: The MAC Address in your lab environment may be different as EVE-NG will generate a new MAC Address for each device within the environment.
- From R1, ping each of the other routers in your lab environment to verify connectivity between them.
R1#ping 10.10.10.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.10.10.2, timeout is 2 seconds: .!!!! Success rate is 80 percent (4/5), round-trip min/avg/max = 1/1/2 ms R1#ping 10.10.10.3 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.10.10.3, timeout is 2 seconds: .!!!! Success rate is 80 percent (4/5), round-trip min/avg/max = 1/1/1 ms R1#ping 10.10.10.4 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.10.10.4, timeout is 2 seconds: .!!!! Success rate is 80 percent (4/5), round-trip min/avg/max = 1/1/2 ms
Notice that the first packet appears to be lost. This is due to the routers performing ARP on the network, learning the MAC Address to IP Address. If you perform a second ping for each device, the first pack will not be lost as it is now loaded into the ARP table until it times out.
- Next, go to the SW1 device. From here, we will view the dynamically learned MAC Addresses that are seen on SW1 and verify that the router’s MAC Addresses are reachable via the expected ports. Ignore any other MAC addresses in the table by using the ‘dynamic’ filter option.
SW1#show mac address-table dynamic Mac Address Table ------------------------------------------- Vlan Mac Address Type Ports ---- ----------- -------- ----- 1 aabb.cc00.2100 DYNAMIC Et0/0 1 aabb.cc00.3100 DYNAMIC Et0/1 1 aabb.cc00.4100 DYNAMIC Et0/3 1 aabb.cc00.5100 DYNAMIC Et0/0 1 aabb.cc00.6100 DYNAMIC Et0/0 Total Mac Addresses for this criterion: 5Do the same on SW2 and compare the differences.
SW2#show mac address-table dynamic Mac Address Table ------------------------------------------- Vlan Mac Address Type Ports ---- ----------- -------- ----- 1 aabb.cc00.1100 DYNAMIC Et0/0 1 aabb.cc00.3100 DYNAMIC Et0/0 1 aabb.cc00.4100 DYNAMIC Et0/0 1 aabb.cc00.5100 DYNAMIC Et0/1 1 aabb.cc00.6100 DYNAMIC Et0/2 Total Mac Addresses for this criterion: 5From SW1, you should notice that the routers connected to SW2 are originating from the E0/0 interface on SW1. From SW2, the routers connected to SW1 are originating from the E0/0 interface of SW2. This is because the E0/0 interface on both of the switches is the “trunk” port between the two switches, which allows them to communicate between each other.
By default, switches will periodically “age out” the MAC address table entries. This is done so that the switch does not fill up the memory tables with stale MAC addresses of devices that may no longer exist on the network. To view the default MAC address aging timer, run the following command from one of your switches.
SW1#show mac address-table aging-time Global Aging Time: 300
Examining the Routing Table
- Connect back to the R1 router. What routes are present within the routing table?
R1#show ip route Codes: L - local, C - connected, S - static, 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 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP a - application route + - replicated route, % - next hop override Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.10.10.0/24 is directly connected, Ethernet0/0 L 10.10.10.1/32 is directly connected, Ethernet0/0The codes area is a definitions table to help you identify the type of route that is listed in the routing table. In the above output, you can see an entry for C and L in the routing table. C represents “connected” while L represents “local”.
The router has a connected route for the 10.10.10.0/24 network, via the Ethernet0/0 interface, along with a local route for the single IP address of 10.10.10.1/32. These routes were automatically created when the IP address 10.10.10.1/24 was configured on the interface Ethernet0/0.
- From R1, we are going to configure an additional IP address on the E0/1 interface.
R1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R1# R1(config)#interface ethernet 0/1 R1(config-if)#ip address 10.10.20.1 255.255.255.0 R1(config-if)#no shutdown R1(config-if)#^Z R1#
- Lets check the routing table again from the R1 device. What routes are now showing in the routing table?
R1#show ip route Codes: L - local, C - connected, S - static, 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 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP a - application route + - replicated route, % - next hop override Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks C 10.10.10.0/24 is directly connected, Ethernet0/0 L 10.10.10.1/32 is directly connected, Ethernet0/0 C 10.10.20.0/24 is directly connected, Ethernet0/1 L 10.10.20.1/32 is directly connected, Ethernet0/1The router has now added two additional routes to the routing table and can now route between hosts on the 10.10.10.0/24 network and the 10.10.20.0/24 network via E0/0 and the E0/1 interfaces.