Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Cisco 1721 LAN to WAN Fails

Ok,  Im new here and somewhat new  to Cisco Routers.  I have used them before, but not for an actual live  enviornment.  I happen to have the fortune of my workplace giving me a  Cisco 1721 for my personal use.  I have a WIC-1ENET card for internet  access and a switch with about 10 pcs attached to it.  I am unable to  have any PC get on the internet but, can see other Computers perfectly  fine.  The router can ping ip addresses and websites.  I am hoping that  with the information below, someone can tell me where I configured it  incorrectly.  The ISP is a Cable internet provider and the IP address is  assigned Dynamicly to me.  I am not sure if the WIC-1ENET card and use  cable internet, but it seems to just be a routing issue between the LAN  and WAN.    Thank you in advance

Translating ""...domain server ( [OK]

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/12/20 ms

C1721#sh ip route
Codes: 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

Gateway of last resort is to network is subnetted, 1 subnets
S [254/0] via, Ethernet0 is subnetted, 1 subnets
C is directly connected, Ethernet0 is subnetted, 1 subnets
C is directly connected, FastEthernet0
S* [254/0] via

C1721#sh int eth0
Ethernet0 is up, line protocol is up
  Hardware is PQUICC Ethernet, address is 0004.dd0c.0633 (bia 0004.dd0c.0633)
  Internet address is 97.94.209.XXX/22
  MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  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 00:00:03, output hang never
  Last clearing of "show interface" counters never
  Input queue: 1/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 5000 bits/sec, 11 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     4052 packets input, 258910 bytes, 0 no buffer
     Received 4046 broadcasts, 0 runts, 0 giants, 0 throttles
     1 input errors, 0 CRC, 0 frame, 1 overrun, 0 ignored
     0 input packets with dribble condition detected
     84 packets output, 9197 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 babbles, 0 late collision, 1 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

C1721# sh run
Building configuration...

Current configuration : 1001 bytes
! Last configuration change at 12:20:31 CST Sat Nov 13 2010
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
hostname C1721
enable password *******
clock timezone CST -5
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
no aaa new-model
ip subnet-zero
ip cef
ip dhcp excluded-address
ip dhcp pool Default
   domain-name Cisco1721
no ftp-server write-enable
interface Ethernet0
ip address dhcp
interface FastEthernet0
ip address
speed auto
ip default-gateway
ip classless
ip route FastEthernet0
ip http server
line con 0
line aux 0
line vty 0 4
password ********



Re: Cisco 1721 LAN to WAN Fails

A good first step is to try NAT.  The following may work for you:

int e0
ip nat outside

int fa0/0
ip nat inside

access-list 100 remark *** NAT Selection ***
access-list 100 permit ip any

ip nat inside source list 110 interface e0 overload

This link is a good read:


CreatePlease login to create content