Which cable to use for GigaEthernet interface

Discussion in 'Cisco' started by Rahan, Aug 25, 2006.

  1. Rahan

    Rahan Guest

    Hi,

    I need to connect two switchs Cisco 2960 by the GigaEthernet interface. This
    interface will be configured as trunk port.

    Which type of network cable (RJ45) i need to use btw the two switchs :
    crossed or normal ?

    Which category of cable it's recommanded to use with the GigaEthernet :
    Category 5 or 5E or 6 ?

    Thank You very much for your help

    Best Regards
    Rahan
     
    Rahan, Aug 25, 2006
    #1
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  2. Rahan

    SAto Guest

    Rahan skrev:
    > Hi,
    >
    > I need to connect two switchs Cisco 2960 by the GigaEthernet interface. This
    > interface will be configured as trunk port.
    >
    > Which type of network cable (RJ45) i need to use btw the two switchs :
    > crossed or normal ?


    You can use either. If you use a straight cable you should turn on the
    auto mdix feature on the switch port. If you use a crossed cable make
    sure all the pairs are crossed not only 2 of the pairs.

    > Which category of cable it's recommanded to use with the GigaEthernet :
    > Category 5 or 5E or 6 ?


    1000Bt was designed to run over Cat5 but the Cat5e and Cat6 is ofcourse
    better.

    But since 2001 the cat5e standard replaced the Cat5 standard so any
    Cat5 cable manufactured after 2001 _should_ be cat5e. (Please do
    correct me if this is wrong).

    -SAto
     
    SAto, Aug 25, 2006
    #2
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  3. Rahan

    Sam Wilson Guest

    In article <>,
    "SAto" <> wrote:

    > Rahan skrev:
    > > Hi,
    > >
    > > I need to connect two switchs Cisco 2960 by the GigaEthernet interface. This
    > > interface will be configured as trunk port.
    > >
    > > Which type of network cable (RJ45) i need to use btw the two switchs :
    > > crossed or normal ?

    >
    > You can use either. If you use a straight cable you should turn on the
    > auto mdix feature on the switch port. If you use a crossed cable make
    > sure all the pairs are crossed not only 2 of the pairs.


    I've asked in another thread and received no answer: why is this? Given
    that 1000base-T transmits and receives on all four pairs simultaneously
    why is crossing pairs even considered? (And it can't be backwards
    compatibility with earlier crossover cables because a 1000base-T
    crossover is wired differently from any other cable!)

    > > Which category of cable it's recommanded to use with the GigaEthernet :
    > > Category 5 or 5E or 6 ?

    >
    > 1000Bt was designed to run over Cat5 but the Cat5e and Cat6 is ofcourse
    > better.


    For some meaning of "better": since GigE should successfully transfer
    all bits of data over properly constucted Cat5/e cabling it's difficult
    to know exactly how Cat6 might do better... :)

    Sam
     
    Sam Wilson, Aug 25, 2006
    #3
  4. Rahan

    SAto Guest

    Sam Wilson skrev:
    > I've asked in another thread and received no answer: why is this? Given
    > that 1000base-T transmits and receives on all four pairs simultaneously
    > why is crossing pairs even considered? (And it can't be backwards
    > compatibility with earlier crossover cables because a 1000base-T
    > crossover is wired differently from any other cable!)


    I do not know. Maybe not too many people know and thats why you haven't
    got an answer.

    > > > Which category of cable it's recommanded to use with the GigaEthernet :
    > > > Category 5 or 5E or 6 ?

    > >
    > > 1000Bt was designed to run over Cat5 but the Cat5e and Cat6 is ofcourse
    > > better.

    >
    > For some meaning of "better": since GigE should successfully transfer
    > all bits of data over properly constucted Cat5/e cabling it's difficult
    > to know exactly how Cat6 might do better... :)


    The Cat5e has FEXT in its requirements, old Cat5 did not.
    Cat6 has stricter requirements meaning less noise fext/next etc.

    All leading to less problems.
    It depends on the setup if you'd notice any diffirence though.
    In a "noisy" envirmont the higher graded cables will do better.

    -SAto
     
    SAto, Aug 25, 2006
    #4
  5. Rahan

    Rahan Guest

    Hi All,

    Thank you very much for your answers !!!

    Nice week

    Best Regards
    Rahan
     
    Rahan, Aug 25, 2006
    #5
  6. Rahan

    chris Guest

    "Rahan" <Rahan@Rahan_badmail.com> wrote in message
    news:44eeae23$0$25058$...
    > Hi,
    >
    > I need to connect two switchs Cisco 2960 by the GigaEthernet interface.
    > This
    > interface will be configured as trunk port.
    >
    > Which type of network cable (RJ45) i need to use btw the two switchs :
    > crossed or normal ?
    >
    > Which category of cable it's recommanded to use with the GigaEthernet :
    > Category 5 or 5E or 6 ?
    >
    > Thank You very much for your help
    >
    > Best Regards
    > Rahan
    >
    >


    Straight cable. In GigE there is no such concept as a "cross over" cable.
    Everything is straight through.

    CAT5 should work okay (I've got a few GigE links on CAT5) but CAT5e is
    better.

    Chris.
     
    chris, Aug 25, 2006
    #6
  7. "chris" <> writes:
    >Straight cable. In GigE there is no such concept as a "cross over" cable.
    >Everything is straight through.


    But, since this is a cisco group... there are cases when you do need to
    make GigE copper cross-over cables when dealing with older Cisco
    gear's GigE ports that didn't support auto MDI/MDIX.
     
    Doug McIntyre, Aug 26, 2006
    #7
  8. Rahan

    Sam Wilson Guest

    In article <>,
    "SAto" <> wrote:

    > Sam Wilson skrev:
    > > I've asked in another thread and received no answer: why is this? Given
    > > that 1000base-T transmits and receives on all four pairs simultaneously
    > > why is crossing pairs even considered? (And it can't be backwards
    > > compatibility with earlier crossover cables because a 1000base-T
    > > crossover is wired differently from any other cable!)

    >
    > I do not know. Maybe not too many people know and thats why you haven't
    > got an answer.


    That's entirely possible, but there aren't many questions too hard for
    folks here!

    Sam
     
    Sam Wilson, Aug 28, 2006
    #8
  9. Rahan

    Sam Wilson Guest

    In article <44efce15$0$28279$>,
    Doug McIntyre <> wrote:

    > "chris" <> writes:
    > >Straight cable. In GigE there is no such concept as a "cross over" cable.
    > >Everything is straight through.


    Not so - see for instance
    <http://www.cisco.com/en/US/products/hw/switches/ps708/products_configura
    tion_guide_chapter09186a00803959e5.html>, table B-2 and figure B-3.

    > But, since this is a cisco group... there are cases when you do need to
    > make GigE copper cross-over cables when dealing with older Cisco
    > gear's GigE ports that didn't support auto MDI/MDIX.


    It's this I'm having trouble with - given the specification of
    1000base-T, why would there ever be a crossover cable?

    Sam
     
    Sam Wilson, Aug 28, 2006
    #9
  10. Rahan

    Sam Wilson Guest

    In article <>,
    Sam Wilson <> wrote:

    > In article <44efce15$0$28279$>,
    > Doug McIntyre <> wrote:
    >
    > > "chris" <> writes:
    > > >Straight cable. In GigE there is no such concept as a "cross over" cable.
    > > >Everything is straight through.

    >
    > Not so - see for instance
    > <http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_guide_chapter09186a00803959e5.html>,
    > table B-2 and figure B-3.


    In looking at that reference again it's clear that table B-2 is nonsense
    (the side 2 pin numbers are wrong and the signal name is wrong for the
    wrongly labelled pin 2) but figure B-3 might be right.

    Sam
     
    Sam Wilson, Aug 28, 2006
    #10
  11. Sam Wilson <> writes:
    >> But, since this is a cisco group... there are cases when you do need to
    >> make GigE copper cross-over cables when dealing with older Cisco
    >> gear's GigE ports that didn't support auto MDI/MDIX.


    >It's this I'm having trouble with - given the specification of
    >1000base-T, why would there ever be a crossover cable?


    Maybe the Cisco parts were developed before the GigE standard
    stabalized before auto MDI/MDIX was implemented. Maybe Cisco didn't
    feel like they needed to support it, or the 3rd part company they
    bought the GBIC parts I've worked with wouldn't support it, but once
    they started going down that path, they had to follow along.

    I don't think its a huge deal overall. There's plenty of odd things in
    the networking world .
     
    Doug McIntyre, Aug 28, 2006
    #11
  12. Rahan

    Sam Wilson Guest

    In article <44f2f8f9$0$28263$>,
    Doug McIntyre <> wrote:

    > Sam Wilson <> writes:
    > >> But, since this is a cisco group... there are cases when you do need to
    > >> make GigE copper cross-over cables when dealing with older Cisco
    > >> gear's GigE ports that didn't support auto MDI/MDIX.

    >
    > >It's this I'm having trouble with - given the specification of
    > >1000base-T, why would there ever be a crossover cable?

    >
    > Maybe the Cisco parts were developed before the GigE standard
    > stabalized before auto MDI/MDIX was implemented. ...


    Look at the description of a GigE port and tell me why any kind of
    MDI/MDIX is needed. AFAICS every port is wired the same and can be
    connected to any other GigE port with a straight cable.

    Sam
     
    Sam Wilson, Aug 28, 2006
    #12
  13. Rahan

    Hansang Bae Guest

    > > > It's this I'm having trouble with - given the specification of
    > > > 1000base-T, why would there ever be a crossover cable?



    Straight Through or "normal" cross over both work. 1000Base-T can do
    MDI/MDIX by default.

    Sam,
    The reason why "normal" crossover cable will work is that EVERY cat5
    (or better) cross-over cable always crossed all eight cables (in
    pairs). So while only four cables are needed for 100Base-T, very very
    few cables were made with just four cables.

    If you pick up any cross over sold at any retail store (RadioShack,
    CompUSA, BestBuys etc) you'll see that the pin out on Cisco's website
    (http://www.cisco.com/en/US/products/hw/switches/ps708/products_configur
    ation_guide_chapter09186a00803959e5.html) is how they are built.

    --

    hsb


    "Somehow I imagined this experience would be more rewarding" Calvin
    **************************ROT13 MY ADDRESS*************************
    Due to the volume of email that I receive, I may not be able to
    reply to emails sent to my account. Please post a followup instead.
    ********************************************************************
     
    Hansang Bae, Aug 29, 2006
    #13
  14. Sam Wilson wrote:

    >
    > I've asked in another thread and received no answer: why is this? Given
    > that 1000base-T transmits and receives on all four pairs simultaneously
    > why is crossing pairs even considered? (And it can't be backwards
    > compatibility with earlier crossover cables because a 1000base-T
    > crossover is wired differently from any other cable!)
    >

    If you connect two like ports together the TX and RX lines must be
    crossed or you end up connecting TX to TX and RX to RX. If one port is
    MDI and the othe MDI-X the TX and RX pairs are on pins that match up
    with a straight cable- an MDI port transmits on one set, an MDI-X on the
    other.

    A Gigabit X-Over is backwards compatible, but a old crossover wired for
    10/100 usually only crosses 2 pairs of the wire (pins 1+2 and 3+6). In a
    gigabit crossover all pairs are crossed, because as you say, all pairs
    are used.

    http://www.ertyu.org/steven_nikkel/ethernetcables.html
     
    Chris Bartram, Aug 31, 2006
    #14
  15. Hansang Bae wrote:
    >>>> It's this I'm having trouble with - given the specification of
    >>>> 1000base-T, why would there ever be a crossover cable?

    >
    >
    > Straight Through or "normal" cross over both work. 1000Base-T can do
    > MDI/MDIX by default.
    >
    > Sam,
    > The reason why "normal" crossover cable will work is that EVERY cat5
    > (or better) cross-over cable always crossed all eight cables (in
    > pairs). So while only four cables are needed for 100Base-T, very very
    > few cables were made with just four cables.
    >
    > If you pick up any cross over sold at any retail store (RadioShack,
    > CompUSA, BestBuys etc) you'll see that the pin out on Cisco's website
    > (http://www.cisco.com/en/US/products/hw/switches/ps708/products_configur
    > ation_guide_chapter09186a00803959e5.html) is how they are built.
    >

    I'm pretty sure I've come across some early Cisco GigE that wouldn't
    auto MDI-MDIX and had to make a x-over.
     
    Chris Bartram, Aug 31, 2006
    #15
  16. Rahan

    Rahan Guest

    "Chris Bartram" <-net.net> a écrit dans le message de
    news:...
    > Sam Wilson wrote:
    >
    > >
    > > I've asked in another thread and received no answer: why is this? Given
    > > that 1000base-T transmits and receives on all four pairs simultaneously
    > > why is crossing pairs even considered? (And it can't be backwards
    > > compatibility with earlier crossover cables because a 1000base-T
    > > crossover is wired differently from any other cable!)
    > >

    > If you connect two like ports together the TX and RX lines must be
    > crossed or you end up connecting TX to TX and RX to RX. If one port is
    > MDI and the othe MDI-X the TX and RX pairs are on pins that match up
    > with a straight cable- an MDI port transmits on one set, an MDI-X on the
    > other.
    >
    > A Gigabit X-Over is backwards compatible, but a old crossover wired for
    > 10/100 usually only crosses 2 pairs of the wire (pins 1+2 and 3+6). In a
    > gigabit crossover all pairs are crossed, because as you say, all pairs
    > are used.
    >
    > http://www.ertyu.org/steven_nikkel/ethernetcables.html



    Thanks a lot Chris for your message and for the link.

    Best Regards
    Rahan
     
    Rahan, Aug 31, 2006
    #16
  17. Chris Bartram wrote:
    > I'm pretty sure I've come across some early Cisco GigE that wouldn't
    > auto MDI-MDIX and had to make a x-over.


    I have 11 2950T-48 swtiches that do not have auto MDIX and we bought
    them brand new in April. :)
     
    Nathan Harmon, Aug 31, 2006
    #17
  18. Rahan

    Hansang Bae Guest

    Chris Bartram wrote:
    > I'm pretty sure I've come across some early Cisco GigE that wouldn't
    > auto MDI-MDIX and had to make a x-over.


    Yup. Very true. It gets worse. Ever lookup the command 'auto
    negotiation' on CCO? It's enough to make your head spin.

    --

    hsb


    "Somehow I imagined this experience would be more rewarding" Calvin
    **************************ROT13 MY ADDRESS*************************
    Due to the volume of email that I receive, I may not be able to
    reply to emails sent to my account. Please post a followup instead.
    ********************************************************************
     
    Hansang Bae, Sep 1, 2006
    #18
  19. Rahan

    Sam Wilson Guest

    In article <>,
    Chris Bartram <-net.net> wrote:

    > Hansang Bae wrote:
    > >>>> It's this I'm having trouble with - given the specification of
    > >>>> 1000base-T, why would there ever be a crossover cable?

    > >
    > >
    > > Straight Through or "normal" cross over both work. 1000Base-T can do
    > > MDI/MDIX by default.


    What's the difference between MDI and MDIX in 1000base-T? I can't find
    a definition. I'll ask again, why would there ever need to be any kind
    of crossover in 1000base-T?

    > > Sam,
    > > The reason why "normal" crossover cable will work is that EVERY cat5
    > > (or better) cross-over cable always crossed all eight cables (in
    > > pairs). So while only four cables are needed for 100Base-T, very very
    > > few cables were made with just four cables.


    The first part of this is simply not true. Until recently the vast
    majority of crossover cables we've ever seen (made for 10/100base-T)
    crossed over the 1-2 and 3-6 pairs but left 4-5 and 7-8 connected
    straight through. There are many references to this kind of cable
    online. [1]

    > > If you pick up any cross over sold at any retail store (RadioShack,
    > > CompUSA, BestBuys etc) you'll see that the pin out on Cisco's website
    > > (http://www.cisco.com/en/US/products/hw/switches/ps708/products_configur
    > > ation_guide_chapter09186a00803959e5.html) is how they are built.


    I can't find any published pinout for those other suppliers, but the
    Cisco page is flawed. Table B-2 which claims to show a 10000base-T
    crossover cable actually shows a straight through cable (with the signal
    mislabelled on pin 2 side 2). Figure B-3 does show what might be a
    crossover cable, but that takes me back to my question of why would you
    bother?

    > I'm pretty sure I've come across some early Cisco GigE that wouldn't
    > auto MDI-MDIX and had to make a x-over.


    What does MDIX mean on 1000base-T? That an MDIX interface sends and
    receives databits 0 and 1 on pins pair 3-6 rather than 1-2, bits 2 and 3
    on 1-2 rather than 3-6 and similarly for bits 4&5 and 6&7 on pairs 4-5
    and 7-8? Why, when if you made all interfaces the same (MDI) they could
    talk to any other with a straight through cable?

    Sam, aka Baffled of Edinburgh


    [1] for example <http://logout.sh/computers/net/gigabit/>,
    <http://www.finnie.org/text/network-tips/> and
    <http://www.derose.net/steve/guides/wiring/> (but why is the
    brown/white-brown pair phase-crossed in the first two?)
     
    Sam Wilson, Sep 1, 2006
    #19
  20. Rahan

    Sam Wilson Guest

    In article <>,
    Chris Bartram <-net.net> wrote:

    > Sam Wilson wrote:
    >
    > >
    > > I've asked in another thread and received no answer: why is this? Given
    > > that 1000base-T transmits and receives on all four pairs simultaneously
    > > why is crossing pairs even considered? (And it can't be backwards
    > > compatibility with earlier crossover cables because a 1000base-T
    > > crossover is wired differently from any other cable!)
    > >

    > If you connect two like ports together the TX and RX lines must be
    > crossed or you end up connecting TX to TX and RX to RX. If one port is
    > MDI and the othe MDI-X the TX and RX pairs are on pins that match up
    > with a straight cable- an MDI port transmits on one set, an MDI-X on the
    > other.


    Not on 1000base-T - all pairs send are bidirectional - there's no TX and
    RX to crossover. Look it up.

    > A Gigabit X-Over is backwards compatible, but a old crossover wired for
    > 10/100 usually only crosses 2 pairs of the wire (pins 1+2 and 3+6). In a
    > gigabit crossover all pairs are crossed, because as you say, all pairs
    > are used.
    >
    > http://www.ertyu.org/steven_nikkel/ethernetcables.html


    I know what sites like that say, I just don't know why they say it -
    allowing a crossover cable just makes life more complicated for everyone.

    Sam
     
    Sam Wilson, Sep 1, 2006
    #20
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