Cisco 1941 ge0/1 won't connect via switch but works when laptop connects

ronald.go · ‎10-03-2016

I have a brand new C1941 to replace old C1840. The strange thing is that ge0/0 works perfectly but ge0/1 doesn't want to go online when connected to any switch; it does wake up when I connect my laptop's gigabit ethernet directly to it.

I've tried changing cables from mdi to mdix and changing port modes in command line, but no joy. Could this be a hardware issue? I am contemplating having it replaced but am worried that this might not resolve my problem...

any advise?

thanks!

Pawan Raut · ‎10-03-2016

Check speed dulplex and media type setting when you connect o switch

ronald.go · ‎10-03-2016

hi

thanks for the reply... i did try all combination of changing to full/auto/half duplex and changing speed from auto to 10/100/1000... but no joy at all... the port was dead when connected to C2960 switch, to Dell N2048 switch, to dlink dgs-1008p switch...

but it comes online immediately when i plug my notebook's (hp elitebook 8440p) into port ge0/1..

port ge0/0 works without any issue when i plug lan card from notebook or plug into the c2960 switch.

Pawan Raut · ‎10-03-2016

check media type. Please provide below output

sh run int Gi0/1

sh int Gi0/1

ronald.go · ‎10-03-2016

hi

sh run int Gi0/1 gives

Building configuration...

Current configuration : 128 bytes

!

interface GigabitEthernet0/1

ip address 10.0.0.69 255.255.255.0

duplex full

speed 1000

no cdp enable

no mop enable

end

sh int Gi0/1 gives

GigabitEthernet0/1 is down, line protocol is down

Hardware is CN Gigabit Ethernet, address is 0081.c405.19e1 (bia 0081.c405.19e1)

Internet address is 10.0.0.69/24

MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full Duplex, 1Gbps, media type is RJ45

output flow-control is unsupported, input flow-control is unsupported

ARP type: ARPA, ARP Timeout 04:00:00

Last input never, output never, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts (0 IP multicasts)

0 runts, 0 giants, 0 throttles

0 input errors, 0 crc, 0 frame, 0 overrun, 0 ignored

0 watchdog, 0 multicast, 0 pause input

0 packets output, 0 bytes, 0 underruns

0 output errors, 0 collisions, 2 interface resets

0 unknown protocol drops

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 pause output

0 output buffer failures, 0 output buffers swapped out

Pawan Raut · ‎10-03-2016

Gi0/1 media type is RJ45 are you using copper cabling between switch and router o fiber cable connectivity?

ronald.go · ‎10-03-2016

hi Pawan

I'm using all copper cabling as the WAN fibre broadband has a mux provided by the ISP that talks gigabit ethernet (RJ45).

e.ciollaro · ‎10-03-2016

Hi

did you try do ask ISP to config their interface in 1000/full and disabling autonegotiation ?

Enrico

ronald.go · ‎10-03-2016

hi Enrico

the mux is actually at my side and so I have been able to change the config to full duplex and fixed speed.

the problem is that even on other switches (except the dlink dgs, which is unmanaged), the port just doesn't go online... but on laptops, it does...

i've opened a ticket with Cisco to have the router replaced...

thanks everyone.

- ron

Leo Laohoo · ‎10-03-2016

the port just doesn't go online... but on laptops, it does...

That's because the laptop can auto-negotiate speed and duplex setting while someone has DISABLED this feature on the router. There is also a potential possibility that a straight-through cable could be use. MDI/MDI-X is disabled on the router when speed and duplex settings are hard-coded.

Remove the speed and duplex settings on the router interface and see if the link goes up or not.

ronald.go · ‎10-03-2016

hi Leo

i've set and reset the speed/duplex setting to all available settings and also on the mux as well as on various switches. just no joy...

i've tried both straight-through and cross cables as well...

the strange thing is that the older 1840 router doesn't have this issue at all on its fastethernet ports...and also i borrowed an 890 router and it works without any issues...

- ron

Leo Laohoo · ‎10-03-2016

the strange thing is that the older 1840 router doesn't have this issue at all on its fastethernet ports...and also i borrowed an 890 router and it works without any issues...

There's only one thing left that is the issue.

What is the difference between the 890, 1840 vs 1941? FastEthernet vs GigabitEthernet.

Run a TDR on the cable used, there's a fairly strong chance Pair "D" on the cable used is faulty.

Another way to test is to use the following settings on the 1941 GigabitEthernet port:

config t
interface Gi 0/1
 duplex auto
 speed auto 10 100
end

ronald.go · ‎10-04-2016

difference between 890, 1840 and 1941: 890 is a gigabit router with built-in 8-port gigabit switch. 1840 is a fastethernet router (2x FE) and the 1941 is a gigabit router (2x GE).

the cable tester reports that the cables i was using were ok.

when you put speed auto, you can't put the other 2 speeds on. I've tried all 4 settings on Gi0/1 (auto, 10, 100, 1000) and none worked.

in any case, Cisco is sending a replacement router tomorrow.

thanks!