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lost dhcp in cisco871

UHLS asked
Last Modified: 2012-06-27
I have a new Cisco 871 running on IOS 12.4(15)T4. this router is connected to my ISP on fe4 and the LAN side is connected to fe2 to a switch. fe1 connects to a 2600 router which provides an alternate path to other isp. fe0 and fe3 are not connected.

the router does NAT and DHCP. the config is working to my satisfaction. My problem is when this router restarts, it lost the dhcp. sh run will not dispaly the dhcp section. I am 100% sure i have wri mem before power cycling it. indeed, whenever i power cycle the router, it only lost that dhcp session but not other config. at one point, i change the hostname and power cycle it and the new hostname stays but not the dhcp.  after i put the dhcp section in, it works the way i want.

version 12.4
no service pad
service tcp-keepalives-in
service tcp-keepalives-out
service timestamps debug datetime msec localtime show-timezone
service timestamps log datetime msec localtime show-timezone
service password-encryption
service sequence-numbers
hostname public253
logging buffered 51200
logging console critical
enable secret 5
enable password 7
no aaa new-model
clock timezone PCTime -5
clock summer-time EDT date Mar 9 2008 2:00 Nov 2 2008 2:00
crypto pki trustpoint TP-self-signed-4227215515
 enrollment selfsigned
 ip-address name-server
 subject-name cn=IOS-Self-Signed-Certificate-4227215515
 revocation-check none
 rsakeypair TP-self-signed-4227215515
ip cef
no ip dhcp use vrf connected
ip dhcp pool sdm-pool1
   import all
   domain-name bethpublic.org
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
no ip bootp server
ip domain name bethpublic.org
ip name-server
 log config
ip tcp synwait-time 10
interface FastEthernet0
interface FastEthernet1
 description uplink to 2600 router
 duplex full
 speed 10
interface FastEthernet2
interface FastEthernet3
interface FastEthernet4
 description Verizon FIOS 20M line
 ip address x.x.x.y
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip nat outside
 ip virtual-reassembly
 speed 100
interface Vlan1
 description BETH public network
 ip address
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip nat inside
 ip virtual-reassembly
 ip tcp adjust-mss 1452
ip forward-protocol nd
ip route
ip route
ip http server
ip http authentication local
ip http secure-server
ip http timeout-policy idle 60 life 86400 requests 10000
ip nat inside source list 102 interface FastEthernet4 overload
logging trap debugging
access-list 102 remark SDM_ACL Category=2
access-list 102 permit ip any
access-list 102 permit ip any
no cdp run
line con 0
 login local
 no modem enable
line aux 0
line vty 0 4
 password 7
 transport input telnet ssh
scheduler max-task-time 5000
scheduler allocate 4000 1000
scheduler interval 500
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this doesnt seem right
my opinion is to try to upgrade your IOS
usually this stuff are IOS bugs
try using 12.4 17a

Also, do a show ver and show file sys to ensure your have enough memory to save the config. An IOS upgrade would certainly be good too.

Good luck.


Hi Folks,

thanks for the lead, I am in touch with Cisco see if it is hardware issue. i have never seen this before.

Really strange. I mean, as long as your saving properly it should be good. I would say a memory issue, either size or corruption, but you did say that it saved the hostname change. that being said, who knows when the memory started having the issue. good luck, please post your finds, I'm definately interested.


I update the IOS to later version which fixes the problem


problems fixed by applying new version of IOS
This one is on us!
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i don't think it is an IOS bug. I have other routers (same model) running the same release of IOS that does not demonstrate the same problem. this is the only one that I am aware of. Since upgrading the IOS fixed it, I don't plan to pursue why it did not work in the first place.

Well just FYI
I work with Cisco routers everyday
and everyday we see bugs
IOSs that work on one router wont necessarily show the bug on it, because this involves the hardware running, you can ask Cisco themselves :) and thats why they call it a BUG

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