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Community Member

Full Duplex issues

        Hello I am seeing a strange issue.

hope to get a little bit of advice on this.

There are two switches connected WS-C3560-48PS-S on one side and WS-C2960-24PC-S on the other side.

the interface configurations are as follows:

WS-C3560-48PS-S

interface FastEthernet0/48

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 101,350

switchport mode trunk

bandwidth 1024

load-interval 30

end

WS-C2960-24PC-S

interface FastEthernet0/24

switchport mode trunk

load-interval 30

duplex full

end

the problem is, the moment i am setting the fa 0/48 on the 3560 switch as a full duplex the interface goes down / down.

the moment i put it back to auto it comes up but the negotiation comes as half duplex and causes duplex mismatch.

Any pointers to fix this ?

many thanks in advance.

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Blue

Re: Full Duplex issues

Upgrade the IOS of your 3560 to a minimum of 12.2(55)SE7.  Go to SE8 if possible.

The IOS your 3560 is using is very buggy.  This could explain why the 3560 link to the 2960 is at full capacity since it's negotiated to half-duplex and it's pushing traffic at half speed.

13 REPLIES

Full Duplex issues

Have you tried setting both the speed and the duplex manually?

Replaced the cable between them?

Purple

Re: Full Duplex issues

  It's probably working as designed.  Someone probably used  a straight thru cable between them and auto mdix is correcting the cabling , as auto mdix only works when the settings are auto for speed and duplex .  When you try to hardcode the speed and duplex the switch will take down the line as it is designed.  You don't need to hardcode the speed and duplex .  Set the 2960 side to duplex auto and leave the 3560 side as auto/auto . If you absolutely feel you have to hardcode then you will have to replace the cable with the correct crossover cable .

Super Bronze

Re: Full Duplex issues

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Posting

I agree with Glen, likely auto is allowing auto-MDI, which will work with straight through or cross over cable.

As far as auto on 3560, with full on the 2960, then yes, auto will assume half duplex.  As Glen also suggests, recommend auto/auto both sides.

Hall of Fame Super Blue

Full Duplex issues

Glen,

Shouldn't MDI-X be working on the 3560 since the port is set to auto/auto?  I understand MDI-X is disabled in 2960 due to the duplex being hardcoded. 

Purple

Full Duplex issues

   I think he said is was working auto auto but duplex was mismatched which it would be because the 2960 is hardcaoded full   and it then went down when he hardcoded the 3560 side.

Hall of Fame Super Blue

Full Duplex issues

If setting the duplex and speed to auto (both switches) don't work, we may need to run a TDR from the 2960. 

If we have to do this, can you please specify if the GigabitEthernet (copper) ports of the 2960 is being used or not.  If it's not then we can do a four-pair TDR test.  Otherwise, the FastEthernet port of the 2960 can only test two pairs. 

Community Member

Full Duplex issues

Thanks a lot all for your replies and your views on this.

I changed the Settings on both sides to speed auto and duplex auto and it negotiates to half as shown below.

2960 Swtich

Fa0/24                       connected    trunk      a-half  a-100 10/100BaseTX

3560 Switch

Fa0/48                      connected    trunk      a-half  a-100 10/100BaseTX

It is really strange as with auto on both sides it should not negotiate to half?

thanks again and look forward to your thoughts.

Hall of Fame Super Blue

Full Duplex issues

Post the output to the command "sh interface " of both interface. 

Next post the "sh version" of both switches.

Community Member

Full Duplex issues

***** 2960 ******

Switch#sh int fa 0/24

FastEthernet0/24 is up, line protocol is up (connected)

  Hardware is Fast Ethernet, address is d0c7.8976.1918 (bia d0c7.8976.1918)

  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

     reliability 255/255, txload 1/255, rxload 2/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Half-duplex, 100Mb/s, media type is 10/100BaseTX

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

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

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  30 second input rate 1093000 bits/sec, 174 packets/sec

  30 second output rate 265000 bits/sec, 191 packets/sec

     45456081 packets input, 33875483713 bytes, 0 no buffer

     Received 290994 broadcasts (252535 multicasts)

     0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 252535 multicast, 0 pause input

     0 input packets with dribble condition detected

     48320984 packets output, 13455690999 bytes, 0 underruns

     0 output errors, 185 collisions, 1 interface resets

     0 babbles, 201 late collision, 0 deferred

     0 lost carrier, 0 no carrier, 0 PAUSE output

     0 output buffer failures, 0 output buffers swapped out

Switch#

Switch#sh run int fa 0/24

Building configuration...

Current configuration : 75 bytes

!

interface FastEthernet0/24

switchport mode trunk

load-interval 30

end

Switch#

--------------------------------------------------

***** 3560 *****

sh run int fa 0/48

Building configuration...

Current configuration : 209 bytes

!

interface FastEthernet0/48

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 101,350

switchport mode trunk

bandwidth 1024

load-interval 30

end

sh int fa 0/48

FastEthernet0/48 is up, line protocol is up (connected)

  Hardware is Fast Ethernet, address is 001e.13aa.8bb4 (bia 001e.13aa.8bb4)

  MTU 1500 bytes, BW 1024 Kbit, DLY 100 usec,

     reliability 255/255, txload 245/255, rxload 79/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Half-duplex, 100Mb/s, media type is 10/100BaseTX

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

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

  Last input 00:00:00, output 00:00:00, 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

  Output queue: 0/40 (size/max)

  30 second input rate 320000 bits/sec, 179 packets/sec

  30 second output rate 986000 bits/sec, 166 packets/sec

     1004372639 packets input, 290931054004 bytes, 0 no buffer

     Received 39107314 broadcasts (26915990 multicasts)

     0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 26915990 multicast, 0 pause input

     0 input packets with dribble condition detected

     971148257 packets output, 780705586557 bytes, 0 underruns

     0 output errors, 1599712 collisions, 0 interface resets

     0 babbles, 9441908 late collision, 0 deferred

     0 lost carrier, 0 no carrier, 0 PAUSE output

     0 output buffer failures, 0 output buffers swapped out

Community Member

Re: Full Duplex issues

***** 3560 Sh ver *****

sh ver

Cisco IOS Software, C3560 Software (C3560-IPSERVICESK9-M), Version 12.2(53)SE2, RELEASE SOFTWARE (fc3)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2010 by Cisco Systems, Inc.

Compiled Wed 21-Apr-10 05:33 by prod_rel_team

Image text-base: 0x01000000, data-base: 0x02E00000

ROM: Bootstrap program is C3560 boot loader

BOOTLDR: C3560 Boot Loader (C3560-HBOOT-M) Version 12.2(44)SE5, RELEASE SOFTWARE (fc1)

Switch uptime is 10 weeks, 2 days, 23 hours, 17 minutes

System returned to ROM by power-on

System image file is "flash:c3560-ipservicesk9-mz.122-53.SE2/c3560-ipservicesk9-mz.122-53.SE2.bin"

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to

export@cisco.com.

cisco WS-C3560-48PS (PowerPC405) processor (revision N0) with 131072K bytes of memory.

Processor board ID CAT1020N055

Last reset from power-on

2 Virtual Ethernet interfaces

48 FastEthernet interfaces

4 Gigabit Ethernet interfaces

The password-recovery mechanism is enabled.

512K bytes of flash-simulated non-volatile configuration memory.

Base ethernet MAC Address       : 00:1E:13:AA:8B:80

Motherboard assembly number     : 73-9676-12

Power supply part number        : 341-0029-05

Motherboard serial number       : CAT10256D36

Power supply serial number      : LIT11337DCM

Model revision number           : N0

Motherboard revision number     : B0

Model number                    : WS-C3560-48PS-S

System serial number            : CAT1020N055

SFP Module assembly part number : 73-7757-03

SFP Module revision Number      : A0

SFP Module serial number        : CAT10243H19

Top Assembly Part Number        : 800-25859-03

Top Assembly Revision Number    : J0

Version ID                      : V04

CLEI Code Number                : CNMV3N0CRC

Hardware Board Revision Number  : 0x01

Switch Ports Model              SW Version            SW Image                

------ ----- -----              ----------            ----------              

*    1 52    WS-C3560-48PS      12.2(53)SE2           C3560-IPSERVICESK9-M    

Configuration register is 0xF

***** 2960 Sh ver *****

Switch#sh version

Cisco IOS Software, C2960 Software (C2960-LANLITEK9-M), Version 12.2(55)SE7, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2013 by Cisco Systems, Inc.

Compiled Mon 28-Jan-13 10:22 by prod_rel_team

Image text-base: 0x00003000, data-base: 0x01400000

ROM: Bootstrap program is C2960 boot loader

BOOTLDR: C2960 Boot Loader (C2960-HBOOT-M) Version 12.2(53r)SEY3, RELEASE SOFTWARE (fc1)

Switch uptime is 2 days, 19 hours, 15 minutes

System returned to ROM by power-on

System image file is "flash:/c2960-lanlitek9-mz.122-55.SE7/c2960-lanlitek9-mz.122-55.SE7.bin"

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to

export@cisco.com.

cisco WS-C2960-24PC-S (PowerPC405) processor (revision K0) with 65536K bytes of memory.

Processor board ID FCQ1719Y3Y4

Last reset from power-on

2 Virtual Ethernet interfaces

24 FastEthernet interfaces

2 Gigabit Ethernet interfaces

The password-recovery mechanism is enabled.

64K bytes of flash-simulated non-volatile configuration memory.

Base ethernet MAC Address       : D0:C7:89:76:19:00

Motherboard assembly number     : 73-12784-05

Power supply part number        : 341-0266-03

Motherboard serial number       : FCQ17190CKN

Power supply serial number      : DCA1713H07L

Model revision number           : K0

Motherboard revision number     : A0

Model number                    : WS-C2960-24PC-S

System serial number            : FCQ1719Y3Y4

Top Assembly Part Number        : 800-33168-02

Top Assembly Revision Number    : A0

Version ID                      : V06

CLEI Code Number                : COMK400DRD

Hardware Board Revision Number  : 0x02

Switch Ports Model              SW Version            SW Image                

------ ----- -----              ----------            ----------              

*    1 26    WS-C2960-24PC-S    12.2(55)SE7           C2960-LANLITEK9-M       

Configuration register is 0xF

Hall of Fame Super Blue

Re: Full Duplex issues

Upgrade the IOS of your 3560 to a minimum of 12.2(55)SE7.  Go to SE8 if possible.

The IOS your 3560 is using is very buggy.  This could explain why the 3560 link to the 2960 is at full capacity since it's negotiated to half-duplex and it's pushing traffic at half speed.

Community Member

Re: Full Duplex issues

Thanks Leo;

i will give it a try.

Hall of Fame Super Blue

Full Duplex issues

Thank you very much for taking the time to rate our posts, Kaushik.

Let us know how you go.

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