Re: Reachibility Issue.

Darby,

Thanks a lot for your suggestion, I would keep in mind the guidelines that
you have made.

I would make sure and double check everything while moving ahead in the lab.

Thanks once again for your prompt reply.

Have a pleasant day!!!

Regards

Sajid

On Sat, Sep 12, 2009 at 11:24 PM, Darby Weaver <darby.weaver_at_gmail.com>wrote:

> Sajid,
>
> To say I've been there and done that is an understatement.
>
> Now let's get to the meat of the matter and why this is the most underly
> stressed topic in all of the CCIE and yet it is probably the biggest reason
> any CCIE Candidate has ever failed the lab - considering what we may already
> know already...
>
> The dreaded encapsulation failed....
>
> So...
>
> Did you hard code your speed/duplex between 3550 and 3560? If so why? I
> know it used to be recommended... until it failed more CCIE Candidates than
> the plague. Don't do it unless asked for.
>
> Did you turn on VTP Pruning between switches and maybe have a transparent
> switch in the middle perhaps?...Lovely...
>
> If this happens you got some choices to make and among these are:
>
> sw t prun vlan x,x,x,x or sw t vlan none for example... None is probably
> too much and individual vlans (like a BB vlan for instance that is on Sw1
> and Sw3 but not say Sw2 or Sw4 in the middle)...
>
> Now some trainers have recommded manually adding the vlans to the switches
> in the middle... However what will you do if this option is taken offen the
> table... Remember no CCIE lab is going to be that easy... by design...
>
> Intervlan Routing... Love this one too... You got a few things that can
> screw you up or that you may have over-learned but not learned well enough
> (if you were like me a time or two anyway)....
>
> So you know encap d 100 under one sub interface of a router and encap d 101
> under the second interface...
>
> So now what do you NEED on the switch to make this work?
>
> Well simple enough:
>
> sw t e d and sw m t and that is it.
>
> Now suppose some fool asked you to accomodate the native vlan...
>
> Well in this case you need:
>
> sw t n vl 100 for example...
>
> But then you get encap failed again...
>
> Well fix it with:
>
> encap d 100 n under the router's sub-interface...
>
> Ok...
>
> But then they asked you to only allow the minimum vlans...
>
> Ok
>
> sw t a v 100,101 under the interface of the switch that connected to the
> router on a stick...
>
> and then they tell you to minimize un-necessary traffic or something to
> that effect....
>
> And you ask yourself... what's left?
>
> Well then we use the following:
>
> sw non (no negotiate) - we don't send un-needed DTP frames to the router
> and why would we, does the router use DTP? Nah!
>
> As for any other encap failed messages keep this in mind in general:
>
> 1. Does the vlan work on the same switch? Yes or no? If not put the
> correct port in the correct vlan.
>
> 2. Does the vlan work across switches? Y/N? If not sh int trunk and see
> if it is pruned... if it is... does it exixt on all transit switches... if
> not... then make it prune ineligible as described above.....
>
> 3. Every once in a blue moon you may find a reason to tag vlan 1 - it's a
> global command... Now if you do this on sw1 what happens to un-tagged
> traffic on sw2, sw3, and sw4? Did you ever give it a second thought...?
>
> Spare the Switch Configs and Spoil the Lab....
>
>
> Hey we can call this a time-saving technique...
>
>
> And to think we would normally run ourselves ragged looking for an L3
> solution to an L2 problem...
>
>
>
>
>
>
>
>
>
>
>
>
>
> On Sat, Sep 12, 2009 at 3:37 AM, sajid mavani <sajidmavani_at_gmail.com>wrote:
>
>> Hello Seniors,
>>
>> I had a query if in case you are not able to ping any of your routers or
>> Backbone interfaces what is the best possible troubleshooting steps.
>>
>> As per my understanding I would follow the following steps.
>>
>> 1) sh ip int b -- check the line protocol
>> 2) check duplex settings
>> 3) trace route check .
>> 4) check for any access-list configured that would block ping
>> reachibility.
>> 5) check proper access vlan passed in the given interface
>> 6) ?
>> 7) ?
>> 8) ?
>> 9) ?
>>
>> Also if possible let me know what would be the best approach to
>> troubleshoot any layer 2 & Layer 3 related problems if possible.
>>
>> Please let me know what would be the best approach, kindly reply to my
>> query
>> as per your convenience
>>
>> Have a pleasant day!!!
>>
>> Regards
>>
>> Sajid .
>>
>>
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>>
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>>
>>
>>
>>
>>
>>
>>
>
>
> --
> Darby Weaver
> Network Engineer
>
> 407-802-7394
> darbyweaver_at_yahoo.com

Blogs and organic groups at http://www.ccie.net
Received on Sat Sep 12 2009 - 23:45:52 ART