Ethernet to FastEthernet config options 2

[Bubbalouie]

I am trying to troubleshoot some performance issues with a Cisco 1751 router that has a WIC-1ENET card installed in addition to the onboard FastEthernet port.

The FastEthernet on the 1751 is connected to a 2924XL switch. No problems with that.

The 1751's WIC-1ENET (Ethernet0/0) is connected to the onboard FastEthernet port (FastEthernet0/0) on a ATT Cisco 2801 managed internet services router. Ethernet0/0 on the 1751 is configured with half-duplex and of course is 10BT. I have a lot of collisions and deferred on the Ethernet0/0 port and I wonder if maybe it's the half-duplex setting causing the collisions and my performance issues.

I have not been able to get an ATT rep to tell me how the FastEthernet port on their router is config'ed (auto, 10, 100, half duplex or full duplex).

What would the ideal setup on an Ethernet to FastEthernet connection be? My ethernet port only has half and full duplex options and is currently set to half. Can I use full duplex instead of half? If ATT has their FastEthernet port set to auto should I have them set it to 10 and either half or full?

Thanks in Advance!

 

[Dinkytoy]

A show cdp entry * may well show you the opposing port settings, but yes full duplex would be preferred.

A mass of collisions does point at a possible duplex mis-match on the port.

 

[vipergg]

You will always have collisions in a half duplex setup which is normal . More than likely the ISP is set as auto so he would be 10/half also . In a half duplex setup utilization above around 35-40% will cause noticeable slowdowns as collisions become increasingly more numerous . If the ISP is auto you want to hardcode , you must hardcode both sides as 10/full otherwise you will have speed/duplex mismatches.

 

[Bubbalouie]

ATT has that FE0/0 port on their 2801 hard coded as 10/half.

When I look at the show int stats for my ethernet port I see

Reliability 255/255 tx 1/255 rx 1/255

If I'm reading that correct I'm no where near that 35-40% mark.

 

[vipergg]

Right at this particular time it is not . You will always have collisions though . If you look at the show int it will tell how many bits per second is going in and out . If you want to eliminate that get ATT to hardcode 10 full and you change your side also which will eliminate all the collisions.

 

[burtsbees]

Post a sh int e0/0 on the 1750.

/

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!

 

[Bubbalouie]

Is there any reason ATT has to run there interface at half duplex?

I replaced the 1751 with a 1750, same setup though. Here is the sh int from ethernet0

MyRouter_1750#show int ethernet0
Ethernet0 is up, line protocol is up
Hardware is PQUICC Ethernet, address is 0004.dd0c.60ff (bia 0004.dd0c.60ff)
Hardware is PQUICC Ethernet, address is 0004.dd0c.60ff (bia 0004.dd0c.60ff)
Internet address is xx.xx.xx.xx/29
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Half-duplex, 10BaseT
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:01, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/10/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 9000 bits/sec, 9 packets/sec
5 minute output rate 53000 bits/sec, 13 packets/sec
2395423 packets input, 1433036375 bytes, 0 no buffer
Received 6861 broadcasts, 0 runts, 0 giants, 0 throttles
7785 input errors, 0 CRC, 0 frame, 0 overrun, 7785 ignored
0 input packets with dribble condition detected
2723328 packets output, 957043774 bytes, 0 underruns
7785 output errors, 6965 collisions, 1 interface resets
0 babbles, 0 late collision, 21450 deferred
7785 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

 

[burtsbees]

Wow---set both sides to 10/full...

/

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!

 

[VinceWhirlwind]

There is no way ion this world your provider is insane and evil enough to actually configure their interface to 10HD - it must have defaulted to that from auto/auto.

Set your Router interface to Auto, kill the link and bring it up again.

 

[Bubbalouie]

I got on with a 'Tier 3' tech and he said theirs was set to 10/half. I asked him specifically because that's how I had mine set and I figured there must have been some kind of interface issue.

Is there any reason AT&T would have to set it that way? Can I tell them to set to 10/full then set mine to 10/full?

 

[burtsbees]

Yes! Tell them yours does 10/full! Email them your sh int!

/!

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!

 

[Bubbalouie]

okay, some idjit swore up and down that it had to be half. i asked to talk to the next guy up the ladder. that guy got his supervisor on the line with him and he said the same thing.

I said 'Burtsbees and VinceWhirlWind say you're blowing smoke up my @ss! Change it to full and let's see what happens!'

Problem solved!

Thanks gents!

 

[Bubbalouie]

Just outta curiousity, I have two other locations that just have a single T1 that is terminated on what ATT calls a 'smartjack'. I hook my 1750's WIC-1ENET directly to a port on the smartjack via a standard straight thru ethernet cable.

Is there any reason ATT has to run those at half duplex?

 

[burtsbees]

The smartjack goes to some device with a T1 interface, and THAT device is what your 1750 plugs into. That device should be 10/full, for best performance, and your 1750 should match that. It can run at 10/half, as long as yours is hard-coded for 10/half, but best policy is to hard-code both sides for 10/full. They probably

A. Assumed that your equipment will only do half-duplex since it is 10MBps
and/or
B. Assigned the same genius to the T1 project

/

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!