CCIE lab ethernet interfaces

do we  just leave them to autonegotiate if they dont specifically ask for anything , i guess im a bit paranoid if an interface ends up half duplex somewhere -- should i be concerned about it ?

Comments

  • Just do exactly what you get asked for.

    With Cisco gear on both ends, as long as both sides are set to auto, you're fine anyway.

    If you're not asked to configure speed/duplex, then the grading scripts won't look for it, and the speed will still be fine for the level of testing that is done.

  • do we  just leave them to autonegotiate if they dont specifically ask for anything , i guess im a bit paranoid if an interface ends up half duplex somewhere -- should i be concerned about it ?

    Hi,

    You won't be asked to solve any physical layer issues in your lab exam. You will be given the default mode for any kind of interface and probably you may not need to change anything on it. I used to have some older routers with Eth interface during my preparation and think about the duplex/speed mismatches in the real lab exam. But the fact is that you will have all the ISR routers in the exam & they will ask more about the technology not the physical layer issues.

    Good luck!

  • peetypeety ✭✭✭

    should i be concerned about it ?

    You should ONLY concern yourself with the questions presented to you.  Nothing more, nothing less.

    Paraphrasing something my wife was told in a recent PMP bootcamp:

     

    ATFQ: Answer the question.

     

    Nothing more, nothing less. http://ieoc.com/forums/p/25027/193876.aspx#193876

  • ATFQ: Answer the question.

    [Y]

  • On the wider subject of "auto negotiation" nothing makes my blood pressure rise quicker than seeing hard coded interfaces.

     

    For 100 duplex issues I see I WILL BET MY SALARY FOR A YEAR 99 are a direct result of hard coding (and one end being missed).

     

     

  • Exceptional scenarios where I can see speed being manipulated without being asked explicitly is QoS say for instance tuning Mls QoS when say a Fast Ethernet interface does not provide enough resolution to "constrain bandwidth" with QoS tools. Here maybe you set speed 10 to constrain bandwidth to 2Mbps based on some queue weightiing configuration....just an example..

  • nickoneill so when is your lab date? I remember you mentioning it as being very soon..

  • i have seen service providers who have policy to hard set speed/duplex at the end of provisioning a service to avoid problems, yet they end up causing more problems for themselves and customers in the long run hehe

     

  • For 100 duplex issues I see I WILL BET MY SALARY FOR A YEAR 99 are a direct result of hard coding (and one end being missed).

     

    I''m glad that auto works so well for most people.  I have seen a lot of failure in a mixed vendor environment, and on certain vendor equipment.  I have personally seen, and have seen many, many reports of some equipment vendor's stuff seemingly randomly failing back to 10/half or 10/full when 100/full or gigabit are available.  Ferrite beads, short cables, new cables, etc fail to fix.

    Most of the dup mismatch failures I have seen are caused by equipment that can't auto on one side linked to a device set to auto on the other.  Obviously this is basically the same thing.

    All this said, hard coding on an access switch will, of course, lead to trouble (and troubleshooting) down the line.

  • The biggest mistake I see is people hard-coding Gig interfaces, because they got burnt 10 years ago with 100/half issues. They don't realise that times have moved on, and Gig in particular should not be hard-coded.

     

    More info here: http://etherealmind.com/ethernet-autonegotiation-works-why-how-standard-should-be-set/

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