Switch to Switch = Crossover?

yanks4everontopyanks4everontop Member Posts: 106
in CCNA & CCENT
I know that's conventially how it's tought but I've also heard some switchs can auto detect the cabling and it doesn't matter. I just wanna be sure before I purchase a bunch of cabling for my home lab. I have 4 routers and 3 switches (2x2950's, 1x3550).
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  • dynamikdynamik Banned Posts: 12,312 ■■■■■■■■■□
    This is the technology: Auto-MDIX - Wikipedia, the free encyclopedia

    I'm not sure if those switches support it or not. You should probably just go with crossover to be safe.

    Where are you getting your cables from? Check out HDMI Cable, Home Theater Accessories, HDMI Products, Cables, Adapters, Video/Audio Switch, Networking, USB, Firewire, Printer Toner, and more! if you haven't yet.
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  • networker050184networker050184 Mod Posts: 11,962 Mod
    Read this.
    An expert is a man who has made all the mistakes which can be made.
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  • miller811miller811 Member Posts: 897
    2950 and 3550 devices will require a cross over if interconnected.
    like devices (router to router) - (switch to switch) - (pc to pc) typically require a crossover cable.

    Newer Cisco switches 2960, 3560 switches do not require a crossover.

    Given the cost difference between the devices, buy or build a crossover.
    I don't claim to be an expert, but I sure would like to become one someday.

    Quest for 11K pages read in 2011
    Page Count total to date - 1283
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  • TurgonTurgon Banned Posts: 6,308 ■■■■■■■■■□
    We did a trunk between two 6000's the other day and the straight cable worked. I imagine it was the autodetect thing. Saved us rummaging for a crossover. I don't think one was to be found nearby *shrug*
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  • EdTheLadEdTheLad Member Posts: 2,111 ■■■■□□□□□□
    3550 supports mdix, 2950 doesn't.So you can connect between the 3550 and 2950's using either straight or crossed and between 2950s with crossed only.
    Networking, sometimes i love it, mostly i hate it.Its all about the $$$$
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  • miller811miller811 Member Posts: 897
    EdTheLad wrote: »
    3550 supports mdix, 2950 doesn't.So you can connect between the 3550 and 2950's using either straight or crossed and between 2950s with crossed only.

    Perhaps you could enlighten me Ed?
    I have 2 3550 and 2 2950 switches in my home lab.
    They will only connect with a crossover cable.

    What is the secret oh wise one?
    I don't claim to be an expert, but I sure would like to become one someday.

    Quest for 11K pages read in 2011
    Page Count total to date - 1283
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  • ElvisGElvisG Member Posts: 167
    I thought a cross-over was required whenever like devices are connected together.
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  • kalebkspkalebksp Member Posts: 1,033 ■■■■■□□□□□
    ElvisG wrote: »
    I thought a cross-over was required whenever like devices are connected together.

    Not if they support Auto-MDIX (Automatic medium-dependent interface crossover), which will automatically detect if a crossover is necessary and change the ports send and receive wires appropriately. For any Cisco testing you do, unless explicitly stated, assume that Auto-MDIX is not in use.
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  • EdTheLadEdTheLad Member Posts: 2,111 ■■■■□□□□□□
    miller811 wrote: »
    Perhaps you could enlighten me Ed?
    I have 2 3550 and 2 2950 switches in my home lab.
    They will only connect with a crossover cable.

    What is the secret oh wise one?

    Its only supported on fa0/25 on my 3500-24T icon_smile.gif.Consider yourself enlightened.

    Switch1#show interfaces transceiver properties
    Name : Fa0/1
    Administrative Speed: auto
    Administrative Duplex: auto
    Administrative Auto-MDIX: N/A
    Administrative Power Inline: enable
    Operational Speed: 100
    Operational Duplex: full
    Operational Auto-MDIX: N/A
    .
    .
    .
    .
    Name : Fa0/25
    Administrative Speed: auto
    Administrative Duplex: auto
    Administrative Auto-MDIX: N/A
    Administrative Power Inline: enable
    Operational Speed: auto
    Operational Duplex: auto
    Operational Auto-MDIX: enable

    Name : Gi0/1
    Administrative Speed: auto
    Administrative Duplex: auto
    Administrative Auto-MDIX: N/A
    Administrative Power Inline: N/A
    Operational Speed: auto
    Operational Duplex: auto
    Operational Auto-MDIX: N/A

    Name : Gi0/2
    Administrative Speed: auto
    Administrative Duplex: auto
    Administrative Auto-MDIX: N/A
    Administrative Power Inline: N/A
    Operational Speed: auto
    Operational Duplex: auto
    Operational Auto-MDIX: N/A
    Networking, sometimes i love it, mostly i hate it.Its all about the $$$$
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  • miller811miller811 Member Posts: 897
    EdTheLad wrote: »
    Its only supported on fa0/25 on my 3500-24T icon_smile.gif.Consider yourself enlightened.


    Thanks dude..... glad to know I was not losing my mind.....
    I don't claim to be an expert, but I sure would like to become one someday.

    Quest for 11K pages read in 2011
    Page Count total to date - 1283
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  • Miikey87Miikey87 Member Posts: 65 ■■□□□□□□□□
    Dont forget your cross over PC -> Router!
    :study: - Never stop learning

    Completed
    Microsoft: 70-640,70-642, 70-646, 70-652, 70-653, 70-662, 70 - 681, 71-169
    Cisco: CCENT, CCNA
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  • pitviperpitviper Member Posts: 1,376 ■■■■■■■□□□
    I found out the hard way that Auto-MDIX is nullified when you force the speed and duplex on the port. There must be a way around it but it was easier for me to plug in a crossover cable than it than it would have been to explain why the network was down :)
    CCNP:Collaboration, CCNP:R&S, CCNA:S, CCNA:V, CCNA, CCENT
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  • tierstentiersten Member Posts: 4,505
    pitviper wrote: »
    I found out the hard way that Auto-MDIX is nullified when you force the speed and duplex on the port. There must be a way around it
    Nope. Disable autoneg and you lose auto-MDIX. It uses the same process to work out whether it needs crossover or straight.
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  • TurgonTurgon Banned Posts: 6,308 ■■■■■■■■■□
    tiersten wrote: »
    Nope. Disable autoneg and you lose auto-MDIX. It uses the same process to work out whether it needs crossover or straight.

    Now THAT makes a lot of sense.
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  • jbaellojbaello Member Posts: 1,191 ■■■□□□□□□□
    dynamik wrote: »
    This is the technology: Auto-MDIX - Wikipedia, the free encyclopedia

    I'm not sure if those switches support it or not. You should probably just go with crossover to be safe.

    Where are you getting your cables from? Check out HDMI Cable, Home Theater Accessories, HDMI Products, Cables, Adapters, Video/Audio Switch, Networking, USB, Firewire, Printer Toner, and more! if you haven't yet.

    Hey thanks for the link they have a very nice S&H, and good price for bulks, just purchased abunch of crossovers, I will return my 6 $ cables I got from Fry's ugh...
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  • BulletzBulletz Member Posts: 159
    switch to switch = crossover
    Show me the way to go 127.0.0.1
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  • james43026james43026 Member Posts: 303 ■■□□□□□□□□
    Perhaps this will help clear it up. Switches are either Auto-MDIX, or they are MDIX meaning that the send and receive are crossed over when you look at the RJ-45 pins. While routers firewalls and PC's are all designed MDI. You can also think of it like this, all end devices are considered DTE (which is the same as MDI), and a switch is considered DCE (same as MDIX), routers are considered DTE as well.
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