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Internet cuts off after a while (Cisco 1721)

BHEbrecht
Level 1
Level 1

I seem to be having some problems with my 1721. For some reason after a while the internet cuts off and the whole network looses internet. And the only way to get the net back is to restart the cable modem. The time between it cutting off is random, sometimes it takes 12hrs or so and sometimes only like 20min. I took the 1721 out of the connection and used a regular linksys wireless router and everything was fine. The internet didn't cut off at all. Then when I put the 1721 back on, the net cut off again. Anyone have an idea? I tried different IOS's, but didn't work. I can't seem to find the problem. Any suggestions would be great, please!

Thanks in advance!

3 Replies 3

thisisshanky
Level 11
Level 11

Can you paste your configs. When the internet cuts off, do see cable/internet lights on cable modem lit ? At the same time, are you able to ping to an Internet IP address from the 1721 console ?

Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus

Just after I posted I reset the router to factory settings and reprogrammed it. But the problem still occured about 11hrs later. The cable lights were still on, showing that the cable has a connection but the activity lights weren't flashing so much. They flashed a few times but nothing major to show that there was activity like a download. I was able to ping inside the network, but as far as pinging outside I wasn't able to at all from the 1721. So again I had to restart the cable modem to get a connection back. It's really wierd. Here's my config:

Building configuration...

Current configuration : 3221 bytes

!

version 12.4

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption

!

hostname Router

!

boot-start-marker

boot-end-marker

!

logging buffered 51200 warnings

enable password

!

no aaa new-model

!

resource policy

!

mmi polling-interval 60

no mmi auto-configure

no mmi pvc

mmi snmp-timeout 180

ip subnet-zero

ip cef

!

!

!

!

!

!

!

crypto pki trustpoint TP-self-signed-345238422

enrollment selfsigned

subject-name cn=IOS-Self-Signed-Certificate-345238422

revocation-check none

rsakeypair TP-self-signed-345238422

!

!

crypto pki certificate chain TP-self-signed-345238422

certificate self-signed 01

3082023D 308201A6 A0030201 02020101 300D0609 2A864886 F70D0101 04050030

30312E30 2C060355 04031325 494F532D 53656C66 2D536967 6E65642D 43657274

69666963 6174652D 33343532 33383432 32301E17 0D303530 38323830 31353134

355A170D 32303031 30313030 30303030 5A303031 2E302C06 03550403 1325494F

532D5365 6C662D53 69676E65 642D4365 72746966 69636174 652D3334 35323338

34323230 819F300D 06092A86 4886F70D 01010105 0003818D 00308189 02818100

A0113C04 A2BFB1EF 0A7515AD B48CABAB 62A3D071 CFF5FB93 F1A66622 93AFA231

FFF184DB 4C811F5F C5A160DC 538BC53C 13D330ED 4BEC291D A525EF15 84B976D9

0E70FB30 B36E6076 975617A2 D65E6819 C404DF0A 5C8C45C0 97E553BE C2C497BE

060A34EB 82CD0BD6 EDBAF34E D0534197 D818677A CCC7278B 22F01F60 B411C767

02030100 01A36730 65300F06 03551D13 0101FF04 05300301 01FF3012 0603551D

11040B30 09820752 6F757465 722E301F 0603551D 23041830 1680145F 67DC559C

31F48C3A 36179FC7 5450A399 00E50430 1D060355 1D0E0416 04145F67 DC559C31

F48C3A36 179FC754 50A39900 E504300D 06092A86 4886F70D 01010405 00038181

00988B5A 33B99E22 65CC140A 5975D719 5AD882A2 52924278 F446E8AE D858A2F4

DEDA6F3B D1102A1F A1288981 19E02218 19F59DD8 1B663F6B C2C7E3F1 40B551DF

00531B64 D1DD34DC 91F46267 C8D48AE2 0CB97398 769F078F 9F8D16DB 5BF6F9EA

38BBAA36 F5B7ED59 FCB8FE40 75AA4988 39EED9D1 04D5F209 B5C356C2 7F10DCDA B9

quit

username privilege 15 secret 5

!

!

!

!

!

interface Ethernet0

ip address dhcp

ip nat outside

ip virtual-reassembly

half-duplex

!

interface FastEthernet0

ip address 192.168.1.1 255.255.255.0

ip nat inside

ip virtual-reassembly

speed auto

!

ip classless

!

ip http server

ip http authentication local

ip http secure-server

ip http timeout-policy idle 600 life 86400 requests 10000

ip nat inside source list 1 interface Ethernet0 overload

!

access-list 1 permit 192.168.1.0 0.0.0.255

!

control-plane

!

banner motd ^C

Authorized access only!

This system is the property of Ebrecht Enterprises.

Disconnect IMMEDIATELY as you are not an authorized user!

Failure to disconnect will result in serious criminal acts,

where you will be prosecuted to the fullest extent of the law.

For authorized access contact:

B Ebrecht

Tel:

E-Mail:

Authorized access only!

Disconnect IMMEDIATELY if you are not an authorized user!

^C

!

line con 0

line aux 0

line vty 0 4

privilege level 15

login local

transport input telnet ssh

line vty 5 15

privilege level 15

login local

transport input telnet ssh

!

end

When I read the description of your issue, my first thought was that it might be an issue with the translation. But if you are not able to access the Internet from a session on the router, then it probably is not a NAT issue.

When the problem occurs if you do show arp, do you see the MAC address of the provider device which serves as your default gateway? Can you ping the address of the device which is your defualt gateway>

HTH

Rick

HTH

Rick