flapping interface help needed! 1

[OzzieGeorge]

Still studying for my CCNA and having set up my home lab running eigrp, I decided to connect it to my adsl modem/router so that I could practice further and transfer files to my pc. All was well and I saved my configs but having been away for a week I fired everything back up and now the interface on the router that connects to the adsl modem/router is flapping, quite slowly (about 10 to 15 seconds between events). The adsl modem is running rip so I am reditributing this and I am wondering if there could be a missmatch somewhere?

The problem is I don't know where to start to troubleshoot this. Can anyone advise? Hopefully this will be a valuable learning curve!

 

[Viconsul]

Firstly, you could check your duplex and speed settings, ensure you don't have a mismatch. You can also run debug on your cisco router to see if it tells you anything.

HTH

 

[OzzieGeorge]

Thanks for replying but unfortunately saying run debug on the router is a bit like saying stare into your chrystal ball!

I can at best turn on debugging, but have no idea how to even view the results, let alone understand them!

This is an old dog new tricks situation (old school voice tech learning Cisco thanks to voip) and whilst I have been trying to learn it for some time, a forced change of job got in the way and so I know enough to be dangerous! I can't even say I'm learning fast (but I am learning) and I see this as a good learning curve, but I really need guidance.

So any help gratefully recieved!

 

[burtsbees]

debug ip interface
debug ppp negotiation
debug ppp authentication
debug ip packet
debug ip eigrp (or debug eigrp
debug atm events

However, it sounds like it's not flapping, but not authenticating (debug ppp neg, deb ppp authen, sh int di0, sh atm int---look for "Showtime!", and sh int di0, look for "bound to:").

/

tim@tim-laptop ~ $ sudo apt-get install windows
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Couldn't find package windows...Thank Goodness!

 

[Viconsul]

Ok, can you post your cisco router config and that of the adsl modem if any? What is the make of the adsl modem?
Also, how have you come to the conclusion that the interface is flapping? Are you getting timeouts when you do a continuos ping? More info is needed to be able to diagnose the problem.

 

[OzzieGeorge]

Config is

Current configuration : 1719 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname router3
!
boot-start-marker
boot system flash
boot-end-marker
!
enable secret 5 $1$qRHf$O4Bp.yM1iX0JDSy2yunDX0
!
no aaa new-model
clock timezone WA 8
no network-clock-participate slot 1
no network-clock-participate wic 0
ip cef
!
!
!
!
no ip domain lookup
ip domain name arthur.com
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
ip ssh time-out 60
!
!
!
!
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface Serial0/0
bandwidth 8000
ip address 192.168.2.2 255.255.255.0
no fair-queue
clock rate 8000000
!
interface FastEthernet0/1
ip address 192.168.1.200 255.255.255.0
duplex auto
speed auto
!
router eigrp 1
redistribute static
redistribute rip metric 10000000 20000 255 1 1500
network 192.168.1.0
network 192.168.2.0
auto-summary
!
router rip
version 2
redistribute eigrp 1 metric 1
network 192.168.1.0
network 192.168.2.0
network 192.168.3.0
!
ip forward-protocol nd
ip route 0.0.0.0 0.0.0.0 192.168.1.1
!
!
no ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
!
voice-port 1/0/0
!
voice-port 1/0/1
!
voice-port 1/1/0
!
voice-port 1/1/1
!
!
!
!
!
!
!
!
gatekeeper
shutdown
!
alias exec r show ip route
alias exec s show ip interface brief
!
line con 0
exec-timeout 0 0
password cisco
logging synchronous
login
line aux 0
password cisco
logging synchronous
login
line vty 0 4
password cisco
logging synchronous
login
transport input telnet ssh
line vty 5 181
password cisco
logging synchronous
login
transport input telnet ssh
!
!
end

Adsl modem is a Netcomm NB6Plus 4w which I don't know how to get a config out of. However it is beginning to appear that the adsl modem is the culprit! I plugged in an older modem (didn't bother connecting it to the net) but when I connect to that all comes up good. So I reset the router and let it run a while then checked the logs. This is the result.

Date/Time Facility Severity Message
2010/04/09 11:45:41 user crit kernel: OAM loopback response not received on VPI/VCI 8/4.
2010/04/09 11:45:39 user crit kernel: OAM loopback response not received on VPI/VCI 8/3.
2010/04/09 11:43:56 user alert kernel: Intrusion -> IN=ppp_8_35_1 OUT= MAC= SRC=93.213.125.194 DST=203.166.245.129 LEN=48 TOS=0x08 PREC=0x20 TTL=117 ID=28224 DF PROTO=TCP SPT=57795 DPT=36388 WINDOW=8192 RES=0x00 SYN URGP=0
2010/04/09 11:43:55 user alert kernel: Intrusion -> IN=ppp_8_35_1 OUT= MAC= SRC=88.91.180.165 DST=203.166.245.129 LEN=48 TOS=0x08 PREC=0x20 TTL=111 ID=12497 DF PROTO=TCP SPT=27818 DPT=36388 WINDOW=8192 RES=0x00 SYN URGP=0
2010/04/09 11:43:54 user alert kernel: Intrusion -> IN=ppp_8_35_1 OUT= MAC= SRC=24.245.84.169 DST=203.166.245.129 LEN=48 TOS=0x08 PREC=0x20 TTL=110 ID=32179 DF PROTO=TCP SPT=56232 DPT=36388 WINDOW=8192 RES=0x00 SYN URGP=0
2010/04/09 11:43:53 user alert kernel: Intrusion -> IN=ppp_8_35_1 OUT= MAC= SRC=79.97.207.186 DST=203.166.245.129 LEN=52 TOS=0x08 PREC=0x20 TTL=109 ID=55773 DF PROTO=TCP SPT=4217 DPT=36388 WINDOW=65535 RES=0x00 SYN URGP=0
2010/04/09 11:43:53 user alert kernel: Intrusion -> IN=ppp_8_35_1 OUT= MAC= SRC=88.91.180.165 DST=203.166.245.129 LEN=48 TOS=0x08 PREC=0x20 TTL=111 ID=11935 DF PROTO=TCP SPT=27818 DPT=36388 WINDOW=8192 RES=0x00 SYN URGP=0


However I have no idea what it means so I am toying with a reset to factory default, but that won't teach me anything even if it fixes it!

Thanks for your help it is appreciated!

 

[OzzieGeorge]

by the way the reason I say it is flapping is because of the following constant output (ignore the date I haven't set it)

*Mar 1 05:46:29.666: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthern
et0/1, changed state to down
--More--
*Mar 1 05:56:59.691: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthern
et0/1, changed state to up
--More--
*Mar 1 05:57:09.691: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthern
et0/1, changed state to down
--More--
*Mar 1 05:59:29.697: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthern
et0/1, changed state to up
--More--
*Mar 1 05:59:39.697: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthern
et0/1, changed state to down
--More--
*Mar 1 06:02:55.001: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthern
et0/1, changed state to up
--More--

 

[Viconsul]

You may try changing the duplex setting on interface FastEthernet0/1 to half duplex and see if that makes any difference or check if you can change the setting on the adsl modem to match your router interface fa0/1 setting.

 

[OzzieGeorge]

Thanks to all for the help!

Finally realised that just before I went on holiday we had the mother of all storms here in Perth. Lightning damage after all that!!!! Bought a shiny new modem router today!