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New Member

what is the meaning of "link type is auto"? in the output of show int fa1/0

Hi, all

I wonder the meaning of "link type is auto"

that was shown in the output of command

"show int fa1/0"

GGJU4F_SSW_S4507#2#sh int fastEthernet 4/25

FastEthernet4/25 is up, line protocol is up (connected)

Hardware is Fast Ethernet Port, address is 001e.f7d9.ede8 (bia 001e.f7d9.ede8)

Description: ## Vlan 920 ##

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

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

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Carrier delay is 0 msec

Full-duplex, 100Mb/s, link type is auto, media type is 10/100BaseTX

input flow-control is unsupported output 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 00:20:48

Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

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

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

1158 packets input, 92184 bytes, 0 no buffer

Received 0 broadcasts (0 multicast)

0 runts, 0 giants, 0 throttles

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

0 input packets with dribble condition detected

1928 packets output, 152207 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier

0 output buffer failures, 0 output buffers swapped out

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: what is the meaning of "link type is auto"? in the output of

Sorry i thought it was mdix at first glance and the previous comments on this thread.

4503-1(config-if)#do show run int g1/1

Building configuration...

Current configuration : 141 bytes

!

interface GigabitEthernet1/1

speed nonegotiate

end

4503-1(config-if)#do show int g1/1 | i Mb

Full-duplex, 1000Mb/s, link type is force-up, media type is 1000BaseSX

It has to do with 'speed nonegotiate'. I believe it has to do with if you copper to fiber conversion. Meaning you have this command available on fiber GBIC ports so you can attempt to negotiate with a remote copper end if necessary. Honestly, I am not 100% sure, but this command is only there on fiber ports and it does change the link type from auto.

10 REPLIES
Hall of Fame Super Silver

Re: what is the meaning of "link type is auto"? in the output of

Hello Sanghee,

the meaning is that the port has not been hard coded for a specific speed and duplex but it will try to negotiate with the NIC of the device connected to it both speed and duplex.

if instead you configure

int fas0/1

speed 100

duplex full

in sh int fas0/1 you should see

link type is 100 Full

Hope to help

Giuseppe

New Member

Re: what is the meaning of "link type is auto"? in the output of

Thanks for your reply.

as you saying, I checked the configuration.

but it has been configured with speed 100 and duplex full already.

Um....

device is cat4507 with IOS_12.2(25)EWA10.bin

would you give me more explanation?

New Member

Re: what is the meaning of "link type is auto"? in the output of

Hi hsh7603,

There are switches with more than one type of media for an interface. For exemple, a single interface can have two connector: a SPF (gbic) or rj-45. In such type of interface you may want to indicate using a command which one you will use. The configuration you choose is reflected in "link type".

int f0/24

media-type sfp

end

New Member

Re: what is the meaning of "link type is auto"? in the output of

Thanks for your reply.

but the switch supports just RJ45 type.

I attatch the show module.

GGJU4F_SG_S4507#1#sh mod

Chassis Type : WS-C4507R

Power consumed by backplane : 40 Watts

Mod Ports Card Type Model Serial No.

---+-----+--------------------------------------+------------------+-----------

1 2 Supervisor IV 1000BaseX (GBIC) WS-X4515 JAE1126NBSK

2 2 Supervisor IV 1000BaseX (GBIC) WS-X4515 JAE1132SYPC

3 48 10/100BaseTX (RJ45) WS-X4148-RJ JAE1123KAJ7

5 6 1000BaseX (GBIC) WS-X4306-GB JAE1129R244

7 48 10/100BaseTX (RJ45) WS-X4148-RJ JAE1142070E

as you recommend

I try it, but media-type command are unseen.

Of course it is right because it doen't support any media-type except RJ45.

In this case,

Link type is shown as auto?

Um....I don't know....

Cisco Employee

Re: what is the meaning of "link type is auto"? in the output of

mdix is probably what it is.

it is used to detect rx from tx incase you ran out of xover cables

'no mdix auto'

New Member

Re: what is the meaning of "link type is auto"? in the output of

I have read that command "show int fa1/0" does not give a clue about speed or duplex being AUTO. So, I don't think that refers to speed or duplex settings.

Can that "link type auto" be related to auto-negotiate trunking?

New Member

Re: what is the meaning of "link type is auto"? in the output of

So do I.

I can't find the "no mdix auto" in configuration.

It doen't seen in both global and interface configuration level.

I am finding the relationship with trunking.

Anyone knows about this issue??

Cisco Employee

Re: what is the meaning of "link type is auto"? in the output of

Sorry i thought it was mdix at first glance and the previous comments on this thread.

4503-1(config-if)#do show run int g1/1

Building configuration...

Current configuration : 141 bytes

!

interface GigabitEthernet1/1

speed nonegotiate

end

4503-1(config-if)#do show int g1/1 | i Mb

Full-duplex, 1000Mb/s, link type is force-up, media type is 1000BaseSX

It has to do with 'speed nonegotiate'. I believe it has to do with if you copper to fiber conversion. Meaning you have this command available on fiber GBIC ports so you can attempt to negotiate with a remote copper end if necessary. Honestly, I am not 100% sure, but this command is only there on fiber ports and it does change the link type from auto.

New Member

Re: what is the meaning of "link type is auto"? in the output of

Thanks for your reply.

It is very helpful to me.

I think it seems to be not necessary for fastehternet because it does not force interface into nonegotiate.

although I change the speed and duplex into 100/full, but "show interface" shows link type is auto.

so link type in fast-ethernet will seem to be auto always.(I am not 100% sure ^^)

Thanks a lot.

New Member

Re: what is the meaning of "link type is auto"? in the output of

Maybe you have the "negotiation auto" configured in the port.

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