This section looks at the tools provided to verify the configuration and connectivity on a Cisco IOS router. You’ll examine a router’s configuration and learn how to view the configuration, status, and statistics on a router’s interface.
There are several tools that can be used to verify that IP addresses are configured correctly. As you learned in the earlier section on ICMP, both ping and trace can be used to verify connectivity on the network. One of the best things to do first is to look at the configuration and make sure that it has been entered correctly. To view the configuration on a Cisco IOS¨Cbased router, type show running – config at the Privileged Mode prompt. Let’s take a look at the output from the show running – config command and view the configuration of a Cisco 1605 router already in production:
hostname Media Inc.
!
logging rate-limit console 10 except errors
no logging console
enable password MyPassword
!
ip subnet-zero
!
no ip dhcp-client network-discovery
!!!
interface Ethernet0
ip address 166.15.108.110 255.255.255.248
ip nat outside
no ip route-cache
no ip mroute-cache
no shut
!
interface Fa0
ip address 10.1.1.2 255.255.0.0
ip nat inside
no ip route-cache
no ip mroute-cache
no shut
!
router rip
network 10.0.0.0
network 166.15.108.0
!
ip nat inside source list 1 interface Ethernet0 Æ’overload
ip nat inside source static tcp 10.1.2.2 53 Æ’166.15.108.106 53 extendable
ip nat inside source static udp 10.1.2.2 53 Æ’166.15.108.106 53 extendable
ip nat inside source static 10.1.2.2 166.15.108.106
ip nat inside source static tcp 10.1.4.27 5631 Æ’166.15.108.110 5631 extendable
ip nat inside source static tcp 10.1.2.1 110 Æ’166.15.108.107 110 extendable
ip nat inside source static tcp 10.1.2.1 25 Æ’166.15.108.107 25 extendable
ip nat inside source static udp 10.1.2.2 50 Æ’166.15.108.106 50 extendable
ip nat inside source static udp 10.1.2.2 47 Æ’166.15.108.106 47 extendable
ip nat inside source static udp 10.1.2.2 6 Æ’166.15.108.106 6 extendable
ip nat inside source static udp 10.1.2.2 1723 Æ’166.15.108.106 1723 extendable
ip nat inside source static udp 10.1.2.2 1023 Æ’166.15.108.106 1023 extendable
ip nat inside source static tcp 10.1.2.2 50 Æ’166.15.108.106 50 extendable
ip nat inside source static tcp 10.1.2.2 47 Æ’166.15.108.106 47 extendable
ip nat inside source static tcp 10.1.2.2 6 Æ’166.15.108.106 6 extendable
ip nat inside source static tcp 10.1.2.2 1723 Æ’166.15.108.106 1723 extendable
ip nat inside source static tcp 10.1.2.2 1023 Æ’166.15.108.106 1023 extendable
ip nat inside source static 10.1.2.1 166.15.108.107
ip classless
ip route 0.0.0.0 0.0.0.0 166.15.108.105
ip route 10.1.2.2 255.255.255.255 Ethernet1
ip route 166.15.108.106 255.255.255.255 10.1.2.2
ip route 166.15.108.107 255.255.255.255 10.1.2.1
no ip http server
!
access-list 1 deny 10.1.2.2
access-list 1 permit 10.0.0.0 0.255.255.255
access-list 101 permit ip 10.3.0.0 0.0.255.255 any
access-list 101 permit ip 10.1.2.0 0.0.0.255 any
access-list 101 permit ip 10.2.2.0 0.0.0.255 any
access-list 101 permit ip 10.4.2.0 0.0.0.255 any
access-list 101 permit tcp any any eq telnet
access-list 101 permit tcp any any eq ftp
access-list 101 permit tcp any host 10.1.2.1 eq pop3
access-list 101 permit tcp any host 10.1.2.1 eq smtp
access-list 101 deny tcp any any eq pop3
access-list 101 deny tcp any any eq smtp
access-list 101 permit tcp any any eq domain
access-list 101 permit udp any any eq domain
access-list 101 permit udp any host 10.1.2.2 eq 1723
access-list 101 permit tcp any host 10.1.2.2 eq 1023
access-list 101 permit udp any host 10.1.2.2 eq 6
access-list 101 permit tcp any host 10.1.2.2 eq 6
access-list 101 permit udp any host 10.1.2.2 eq 47
access-list 101 permit tcp any host 10.1.2.2 eq 47
access-list 101 permit udp any host 10.1.2.2 eq 50
access-list 101 permit tcp any host 10.1.2.2 eq 50
access-list 101 permit ip host 10.1.4.200 any
access-list 101 permit ip host 10.1.4.201 any
access-list 101 permit ip host 10.1.4.202 any
access-list 101 permit ip host 10.1.4.203 any
access-list 101 permit ip host 10.1.4.204 any
access-list 101 permit ip host 10.1.4.205 any
access-list 101 permit ip host 10.1.4.206 any
access-list 101 permit ip host 10.1.4.207 any
access-list 101 permit ip host 10.1.4.208 any
access-list 101 permit ip host 10.1.4.209 any
access-list 101 permit ip host 10.1.4.210 any
access-list 101 permit ip host 10.1.4.211 any
access-list 101 permit ip host 10.1.4.212 any
access-list 101 deny tcp 10.0.0.0 0.255.255.255 Æ’any eq www
access-list 101 permit ip any any
!!!
line con 0
exec-timeout 0 0
password MyPassword
login
line vty 0 4
password MyPassword
login
!
end
This is a very complex configuration, since the company uses Network Address Translation (NAT). They also control the IP addresses that can have access to the Internet. Sometimes looking at the interface’s configuration, statistics, and status to see if the interface is up and running correctly can help to verify connectivity as well. To do this, you need to look at the interface. Use the show interface command. Let’s take a look at the output:
Media Inc.# show interface
Ethernet0 is up, line protocol is up
Hardware is PQUICC Ethernet, address is 0007.eb32
Æ’.d6a3 (bia 0007.eb32.d6a3)
Internet address is 207.212.78.110/29
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 2/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 10BaseT
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang Æ’never
Last clearing of “show interface” counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 4/75, 0 drops
5 minute input rate 102000 bits/sec, 31 packets/sec
5 minute output rate 31000 bits/sec, 30 packets/sec
7841018 packets input, 4191596924 bytes,
Æ’0 no buffer
Received 209 broadcasts, 0 runts, 0 giants,
Æ’0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun,
Æ’0 ignored
0 input packets with dribble condition detected
7375598 packets output, 1233071510 bytes,
Æ’0 underruns
6309 output errors, 9998 collisions,
Æ’2 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers Æ’swapped out
FastEthernet0 is up, line protocol is up
Hardware is PQUICC_FEC, address is 0007.eb32.d6a2 Æ’(bia 0007.eb32.d6a2)
Internet address is 10.1.1.2/16
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Auto-duplex, 10Mb/s, 100BaseTX/FX
The show ip interface brief command is great for getting a quick look at the IP address and
whether the interface is functioning. Let¡¯s take a look at the output from the command:
Media Inc.#show ip int brief
Interface IP-Address OK? Method Status Protocol
Ethernet0 207.212.78.110 YES NVRAM up up
FastEthernet0 10.1.1.2 YES NVRAM up up
Related posts:
- Configure Extended Access Lists to Filter IP Traffic
- Monitor and Verify Selected Access list Operations on the Router
- Configure Standard Access Lists to Figure IP Traffic Lab
- Configure Standard Access Lists to Figure IP Traffic
- Access List Operations on the Router
- Configure IP addresses Exams Points
- IP Addresses and IPX Addresses
- Data link and Network Addresses
- MAC Addresses Exams Point
- Classes of IP addresses and subnetting
