From: Scott Morris (smorris@ipexpert.com)
Date: Wed Oct 24 2007 - 11:19:17 ART
While true, logically a same-to-same wouldn't count as a mathematical
"combination".
Thanks though! :) I got my laughter this morning!
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE-M
#153, JNCIS-ER, CISSP, et al.
CCSI/JNCI-M/JNCI-ER
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
A Cisco Learning Partner - We Accept Learning Credits!
smorris@ipexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
http://www.ipexpert.com
_____
From: Joseph Saad [mailto:joseph.samir.saad@gmail.com]
Sent: Wednesday, October 24, 2007 6:11 AM
To: Tarun Pahuja
Cc: smorris@ipexpert.com; Joseph Brunner; Ananth Vk; ccielab@groupstudy.com
Subject: Re: Query : Network Types
This formula assumes that the same type can't be used at the 2 ends. i.e.
once you pick a type from the basket, it is no longer available for you to
match on the other end.
Hence, this formula is not correct.
15 is the correct number of different combinations irrespective of timers
and irrespective whether a DR needs to be elected.
Scott wins ... but whom am I to judge.
Cheers,
Joseph.
On 10/24/07, Tarun Pahuja <pahujat@gmail.com> wrote:
Slight correction, Math says that if you have 5 possible combinations, the
possible number of combinations would be n(n-1)/2. Therefore, The possible
ways would have been 10 and not 15(in which one could try to form adjacency
).
5X(5-1)/2 = 10
Thanks,
Tarun Pahuja
CCIE#7707(R&S,Security,SP,Voice,Storage),CCSI
On 10/23/07, Scott Morris <smorris@ipexpert.com> wrote:
>
> hehehehe... Yes, the response was a joke. (sort of)
>
> There are indeed 15 ways to combine those network types, math doesn't
> lie. No, all of them will not work together.
>
> However, that's the point of learning is it not? If you are interested in
> finding some document which may or may not contain all the possibilities
and
> memorize it, go ahead. If you are interested in trying something out and
> attempting to learn WHY it will or will not work, you'll have much better
> retention of knowledge and depth of knowledge at that point.
>
> The second path will take a little longer, but the long-term reward is
> much greater.
>
> "Any fool can know. The point is to understand." -- Albert Einstein
>
>
> Scott Morris, *CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713,
> JNCIE-M #153**, JNCIS-ER, CISSP, et al.*
> *CCSI/JNCI-M/JNCI-ER*
> VP - Technical Training - IPexpert, Inc.
> IPexpert Sr. Technical Instructor
>
> A Cisco Learning Partner - We Accept Learning Credits!
>
> smorris@ipexpert.com
>
> Telephone: +1.810.326.1444
> Fax: +1.810.454.0130
> http://www.ipexpert.com
> ------------------------------
> *From:* Tarun Pahuja [mailto: pahujat@gmail.com]
> *Sent:* Tuesday, October 23, 2007 4:15 AM
> *To:* Scott Morris
> *Cc:* Joseph Brunner; Ananth Vk; ccielab@groupstudy.com
<mailto:ccielab@groupstudy.com>
> *Subject:* Re: Query : Network Types
>
>
> Scott,
> I hope your last response was not a Joke ;-) I know you like to
> joke sometimes........
>
> There are 5 different type of network types under ospf namely:
>
> 1. broadcast
> 2. non-broadcast
> 3. point-to-point
> 4. point-to-multipoint
> 5. point-to-multipoint non-broadcast
>
> One can not simply use 5+4+3+2+1 logic or any other mathematical logic to
> figure out what possible combinations are possible. Every network type
under
> ospf has certain characteristics(DR/BDR,Hello,Dead interval,etc). For ospf
> to form adjacency with neighbors certain conditions must be met or else no
> relationship would be formed. Additionally, as per Cisco Routing and
> Switching official exam guide, it is not recommended to form neighbor
> relationship between ospf network types requiring a DR/BDR and network
types
> that do not require a DR/BDR in NBMA networks even though the neighbor
> relation comes up after fine tuning the Hello/Dead intervals.
>
> http://books.google.com/books?id=dKzpj4r7KCwC
<http://books.google.com/books?id=dKzpj4r7KCwC&pg=PA270&lpg=PA270&dq=nbma+os
pf+network+type&source=web&ots=qLxQS3ST7M&sig=VpZJ06-c7z-fn6wz4MPb8Ocwk-U>
&pg=PA270&lpg=PA270&dq=nbma+ospf+network+type&source=web&ots=qLxQS3ST7M&sig=
VpZJ06-c7z-fn6wz4MPb8Ocwk-U
>
>
> HTH,
> Tarun Pahuja
> CCIE#7707(R&S,Security,SP,Voice,Storage),CCSI
>
>
>
>
>
> On 10/22/07, Scott Morris <smorris@ipexpert.com> wrote:
> >
> > It's just math. 5+4+3+2+1 I didn't spend any time thinking more about
> > what
> > things would/wouldn't change. That's the part about studying. :)
> >
> > -----Original Message-----
> > From: Joseph Brunner [mailto:joe@affirmedsystems.com]
> > Sent: Monday, October 22, 2007 10:45 AM
> > To: 'Scott Morris'; 'Ananth Vk'; ccielab@groupstudy.com
> > Subject: RE: Query : Network Types
> >
> > Scott is that 15 number including when we use 2 network types that
> > do/don't
> > require a dr and change the timers?
> >
> > -Joe
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto: nobody@groupstudy.com] On Behalf Of
> > Scott Morris
> > Sent: Monday, October 22, 2007 10:20 AM
> > To: 'Ananth Vk'; ccielab@groupstudy.com
> > Subject: RE: Query : Network Types
> >
> > As long as you have labbed those up and SEEN how things work, you'll
> > have no
> > worry about the order or combination or anything.
> >
> > There are 5 network types:
> >
> > 1. broadcast
> > 2. non-broadcast
> > 3. point-to-point
> > 4. point-to-multipoint
> > 5. point-to-multipoint non-broadcast
> >
> > If you are aware of the details of each, you'll be
> > fine. Mathematically,
> > there are 15 different combinations you can come up with.
> >
> > HTH,
> >
> >
> > Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713,
> > JNCIE-M
> > #153, JNCIS-ER, CISSP, et al.
> > CCSI/JNCI-M/JNCI-ER
> > VP - Technical Training - IPexpert, Inc.
> > IPexpert Sr. Technical Instructor
> >
> > A Cisco Learning Partner - We Accept Learning Credits!
> >
> > smorris@ipexpert.com
> >
> > Telephone: +1.810.326.1444
> > Fax: +1.810.454.0130
> > http://www.ipexpert.com
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > Ananth Vk
> > Sent: Monday, October 22, 2007 5:31 AM
> > To: ccielab@groupstudy.com
> > Subject: Query : Network Types
> >
> > Hi
> >
> > I just wanted to confirm that these are the following network types
> > regardless of layer 3 protocol
> >
> > 1. point to point - serial point to point links
> >
> > 2. broadcast - lan
> >
> > 3. NBMA (FR/ATM/etc)
> >
> > A. Pure Point-to-Point Configuration (each VC on a separate
> > subinterface)
> >
> > B. Pure Multipoint Configuration (no subinterfaces)
> >
> > C. Hybrid Configuration (point-to-point and multipoint subinterfaces)
> >
> > I got this from a cisco link, is this the right order/fashion that i
> > should
> > remember / is there a different perspective ?
> >
> > Pls advice !
> >
> >
> > Thanks
> > Ananth
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