Catalyst 3750 interface explaination

[chialun]

Dear Sir,

I don't understand as follows :-

1.) why on Catalyst3750 interface fastethernet 1/0/1 ?? <--- what's the meaning of 1/0/1 ?

2.) what's the meaning of no mdix auto?

Please explain and advise.

Thank you.

[rhltechie]

The 3750 switches can be stacked together via fiber cables. Hence the three sets of numbers.

1 / 0 / 1

the first "1" is the switch number (if you had two stacked together the second with be "2/0/1")

the "0" is the module or slot number on the switch (always 0 on the Catalyst 3750 switch).

The last "1" is the port number. (on a normal 48 port switch you would have 1/0/1 - 1/0/48)

For the mdix:

"You can use the mdix auto interface configuration command in the CLI to enable the automatic medium-dependent interface crossover (Auto-MDIX) feature. When the Auto-MDIX feature is enabled, the switch detects the required cable type for copper Ethernet connections and configures the interfaces accordingly. Therefore, you can use either a crossover or a straight-through cable for connections to a copper 10/100, 10/100/1000, or 1000BASE-T SFP module port on the switch, regardless of the type of device on the other end of the connection."

The following page can probably guide you more:

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_guide_chapter09186a00801cdea4.html

[chialun]

Hi rhltechnie,

Thank you for your good response. However i've some curiousity which as follows:-

1.) 1/0/1 --> so the second will be 2/0/1 .

How to stacked both of the catalyst 3750? just purchase one stackable cable to link both of them and will it automatically configure the 2nd switch from 1/0/1 to 2/0/1 after we plug in the stackable cable into the 2nd switch.

2.) so i put "no mdix auto" on catalyst 3750, what's the meaning and impact?

Thanks a lots.

[Bobby Thekkekandam]

Hi,

1)See the following document to learn how to stack your 3750s:

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750/12225see/scg/swstack.htm

2) Auto MDIX (Media-Dependent Interface Crossover) is a feature built into some ethernet controllers that allows the port, if needed, to perform an internal crossover when a straight cable is detected during the auto-negotiation phase.

The feature is documented here:

http://www.cisco.com/en/US/products/hw/switches/ps5528/products_installation_guide_chapter09186a0080331b76.html

HTH,

Bobby

*Please rate helpful posts.

[m.benhassine]

The 3750 has many interesting features, I recommaned you go through before you connect your switches in a production environment.

Basically, you should provision your stack master with the number of switches and their types. You could provision as well the interfaces with their corresponding configurations, even though the other elements are still not connected yet. This way, you ensure, when you add a provisioned element with the right number, it will take exactly the provisioned configuration you've already set on the master,... as well when changing an element with an other, when moving it,... you will have just to provision its number and then connect it to the stack while is not yet powered on.

Second, it is recommanded to set priority to each element, this way you will have a deterministic configuration and you know in advance which one will be reelected as master in any sitution.

If no provision is set on the stack master, when you connect a switch, it has by default the number "1", in this case the newly added switch will take the lowest switch number available (2).

1.) 1/0/1 --> so the second will be 2/0/1.

And to address its ports you tape: 2/0/1, 2/0/2, 2/0/3,2/0/4,...2/0/24,...

How to stacked both of the catalyst 3750? just purchase one stackable cable to link both of them and will it automatically configure the 2nd switch from 1/0/1 to 2/0/1 after we plug in the stackable cable into the 2nd switch.

For large deployment I recommand the switches to be provisioned manually: Before stacking the switches:

1/ power on the switch that will be the stack master, then wait till it will be in "Ready" state by issuing "show switch detail" command.

2/ Provision the stack master with the desired stack configuration (numbers of switches, types of switches and interfaces configurations).

3/ Reload the stack master.

4/ Provision the second switch with its number and type.

5/ Power off the second switch afetr having saved its configuration.

6/ Stack the second switch to the stack master.

7/ power it on. It will take the provisioned configuration on the stack master.

The advantage of this procedure is that switches could not be renumbered while stacked and running.

Repeat steps 4 to 7 for each new element having been provisioned in the stack master.

Do not forget to save after each step.

2.) so i put "no mdix auto" on catalyst 3750, what's the meaning and impact?

no mdix-auto will disable the advanced feature of abstructing the type of cable (staight throu or cross over). You will downgrade to the standard interfaces specifications. In fact, mdix-auto (activated by default) permits to not to have the "overhead" of distinguishing crossover and straight throu cables, the interfaces will adapt automatically to the type of cable.

An other advantage of this function is that it opimises (combined with other functions) error and recovery procedures in layers 1 and 2.

Mohamed BEN HASSINE