Re: ISIS L1 vs L2

I'm with you, bro. I got the CCIE first, so I definitely agree with you
1000%. Didn't you see the ;) ?

On Wed, Nov 28, 2012 at 1:44 PM, Marko Milivojevic <markom_at_ipexpert.com>wrote:

> But you are. Like the example in this thread. Choosing flat L1/L2
> instead of flat L2 would double the memory requirements for IS-IS
> alone. It's an issue of scale and that is one of the fundamentals in
> the network design.
>
> I *firmly* believe that network designer/architect must have 100%
> grasp of bit-level issues. Not necessarily the configuration, but how
> protocols work, operate, interoperate, etc. is an absolute
> prerequisite to be a good network designer/architect.
>
> --
> Marko Milivojevic - CCIE #18427 (SP R&S)
> Senior CCIE Instructor - IPexpert
>
> On Wed, Nov 28, 2012 at 10:30 AM, Ronnie Angello
> <ronnie.angello_at_gmail.com> wrote:
> > Yeah, I have to agree. I actually went to the CP site to download the
> > errata, and didn't even find what I was looking for. I recall some shaky
> > stuff around OSPF stub area types and what LSA types are allowed/not
> > allowed. Found some other stuff that I don't recall... Also agree that
> > it's the best routing design book that I've read. There are some good
> ones
> > out there that are focused on individual routing protocols or
> technologies,
> > but this is the best when it comes to general L3 network design.
> >
> > While you have to verify all technical content, the pieces that I find
> > particularly good - general routed design theory, topology design theory,
> > tunneling technologies and interaction with routing, fast convergence,
> down
> > detection, etc. The bit/byte level detail stuff needs some
> review/cleaning
> > up as you've pointed out, but then again us CCDEs aren't supposed to care
> > about that. :)
> >
> > Ronnie
> >
> >
> > On Wed, Nov 28, 2012 at 1:06 PM, Marko Milivojevic <markom_at_ipexpert.com>
> > wrote:
> >>
> >> ~sigh~ since you bring ORD again, I will now write what I deleted
> earlier.
> >>
> >> It's a truly terrible book. I read it 3-4 times and apart from blatant
> >> erros, there are MANY things in there that make no sense. The problem
> >> is - it's still probably the best overall routing design book from
> >> Cisco Press. There are others, more focused ones (like Definitive MPLS
> >> Network Designs), but it's shocking how this book passed the technical
> >> review. I suppose everyone reviewing was in awe of the author(s).
> >>
> >> --
> >> Marko Milivojevic - CCIE #18427 (SP R&S)
> >> Senior CCIE Instructor - IPexpert
> >>
> >> On Wed, Nov 28, 2012 at 10:02 AM, Ronnie Angello
> >> <ronnie.angello_at_gmail.com> wrote:
> >> > LOL yeah, he was talking about that one before. That's one of his
> >> > titles that I haven't bought... Looks like price isn't an issue
> though!
> >> >
> >> > So CCDE tip of the day... always ask why! I blindly followed ORD
> today
> >> > (probably because I've read it like 8 times) and got bit... Don't
> accept
> >> > the stuff in books or case studies as is. Ask why...
> >> >
> >> > Ronnie
> >> >
> >> > Sent from my iPhone
> >> >
> >> > On Nov 28, 2012, at 12:54 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:
> >> >
> >> >> Speaking of CCDE and Optimal Routing Design, INE had a CCDE study
> >> >> session last week and I was showing people recommended books to go
> through
> >> >> on Amazon. I was going through the list of books that Russ White
> wrote and
> >> >> I came across this gem:
> >> >>
> >> >> Loss of Carrier [Paperback]
> >> >> Russ White (Author)
> >> >>
> >> >> Jess Wirth lives a dreary life. He spends most of his time crammed
> >> >> inside a cubicle, toiling as a network engineer and stewing over the
> details
> >> >> of his ugly divorce. But when he finds his co-worker dead in the
> basement of
> >> >> their office, Jess's life takes a surprising-and unpleasant-turn.
> The police
> >> >> quickly declare the death a suicide, but Jess isn't so sure. Not
> long after
> >> >> he begins digging into the victim's work, another co-worker turns up
> dead,
> >> >> convincing him once and for all that something sinister is brewing
> behind
> >> >> the cubicle walls. His investigation leads him to a mysterious woman
> name
> >> >> Leah, who pushes him to entrust her with the information he's
> collected
> >> >> about his dead colleagues. Wary of Leah's motives yet inexorably
> drawn to
> >> >> her, Jess keeps her at arm's length...until an attempt is made on
> both their
> >> >> lives. Realizing they are close on the trail of a dangerous
> criminal, the
> >> >> pair race to expose a data theft ring before they become the
> killer's next
> >> >> victims.
> >> >>
> >> >>
> >> >> It's a networking murder mystery by Russ White :) Kindle edition is
> >> >> only $1.99. This is totally on my reading list now ;)
> >> >>
> >> >> Brian
> >> >>
> >> >>
> >> >>
> >> >> -----Original Message-----
> >> >> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On
> Behalf Of
> >> >> Brian McGahan
> >> >> Sent: Wednesday, November 28, 2012 11:48 AM
> >> >> To: Ronnie Angello
> >> >> Cc: shiran guez; Routing Freak; Cisco certification
> >> >> Subject: RE: ISIS L1 vs L2
> >> >>
> >> >> The best part being the drunker we became the louder we became, and
> the
> >> >> louder person is always right by default ;)
> >> >>
> >> >>
> >> >>
> >> >> From: Ronnie Angello [mailto:ronnie.angello_at_gmail.com]
> >> >> Sent: Wednesday, November 28, 2012 11:22 AM
> >> >> To: Brian McGahan
> >> >> Cc: shiran guez; Routing Freak; Cisco certification
> >> >> Subject: Re: ISIS L1 vs L2
> >> >>
> >> >> Reminds me of the drunken OSPF vs IS-IS discussion in Chicago after
> >> >> CCDE. Remember that? ;)
> >> >>
> >> >> Sent from my iPhone
> >> >>
> >> >> On Nov 28, 2012, at 10:48 AM, Brian McGahan
> >> >> <bmcgahan_at_ine.com<mailto:bmcgahan_at_ine.com>> wrote:
> >> >> If youb re not going to grow to other areas then it doesnb t matter;
> >> >> flat L1 everywhere is the same as flat L2 everywhere. For example
> think of
> >> >> it within the scope of OSPF. If you have an OSPF network that is
> area 0
> >> >> everywhere vs. a network that is area 1 everywhere, they will both
> have the
> >> >> same operational behavior. All routers and links are in the same
> flooding
> >> >> domain and failure domain. The problem comes in if you want to grow
> the
> >> >> network to other areas. With OSPF flat area 1 wonb t work because
> you canb
> >> >> t add other non-area 0 areas. The same is true with IS-IS.
> >> >>
> >> >> Most flat IS-IS networks use L2 everywhere, just in case there is a
> >> >> need to add hierarchy later. But like I said if youb re never going
> to add
> >> >> hierarchy in the future it doesnb t matter, just with L2 everywhere
> you have
> >> >> that option down the road without having to do a major redesign.
> >> >>
> >> >> The only thing you want to make sure *not* to do is to run L1 and L2
> on
> >> >> all links. This would be the same as running both OSPF area 0 and
> area 1 on
> >> >> all links, or running two separate OSPF processes that are enabled
> on all
> >> >> links. The only thing L1 and L2 will do for you if you run it
> everywhere is
> >> >> to increase the amount of memory and CPU resources that your routers
> need,
> >> >> and potentially add to your convergence time when a failure event
> occurs.
> >> >>
> >> >> You may want to check out the book b OSPF and IS-IS: Choosing an IGP
> >> >> for Large-Scale Networksb by Jeff Doyle for more info on the
> comparison of
> >> >> the two.
> >> >>
> >> >>
> >> >> HTH,
> >> >>
> >> >> Brian McGahan, CCIE #8593 (R&S/SP/Security)
> >> >> bmcgahan_at_INE.com<mailto:bmcgahan_at_INE.com>
> >> >>
> >> >> Internetwork Expert, Inc.
> >> >> http://www.INE.com
> >> >>
> >> >>
> >> >>
> >> >> From: Ronnie Angello [mailto:ronnie.angello_at_gmail.com]
> >> >> Sent: Wednesday, November 28, 2012 9:34 AM
> >> >> To: shiran guez
> >> >> Cc: Routing Freak; Cisco certification; Brian McGahan; Narbik
> >> >> Kocharians; Marko Milivojevic; Brian Dennis
> >> >> Subject: Re: ISIS L1 vs L2
> >> >>
> >> >> So at least we agree don't do L1 only... I honestly haven't done
> much
> >> >> real world IS-IS design, but my reference is Optimal Routing Design
> (Chapter
> >> >> 5, page 190).
> >> >>
> >> >> Ronnie
> >> >>
> >> >> Sent from my iPhone
> >> >>
> >> >> On Nov 28, 2012, at 9:56 AM, shiran guez
> >> >> <shiranp3_at_gmail.com<mailto:shiranp3_at_gmail.com>> wrote:
> >> >> L1/L2 everywhere is not making much sense as you will have redundant
> >> >> database for both L1 and L2. normally Core you will work L2 edge to
> "stub"
> >> >> you will do L1/L2 and stub networks you will set L1, L2 will provide
> you
> >> >> future flexibility, even if you think that you will not expand or
> change, it
> >> >> is not a good design to do a limit yourself from the start, it does
> not cost
> >> >> anything to do it L2, but it will cost plenty if you will need to
> change
> >> >> Core in future.
> >> >>
> >> >> my 2 cents :-)
> >> >>
> >> >> On Wed, Nov 28, 2012 at 3:18 PM, Ronnie Angello
> >> >> <ronnie.angello_at_gmail.com<mailto:ronnie.angello_at_gmail.com>> wrote:
> >> >> A single L1/L2 domain would be best as it provides flexibility...
> That
> >> >> way you already have a contiguous L2 domain. If the network grows,
> it's
> >> >> easier to add an L1 routing domain than it is to add an L2 routing
> domain.
> >> >> You just add an L1 IS to the edge and push the L1 domain into the
> network...
> >> >>
> >> >> Ronnie
> >> >>
> >> >> Sent from my iPhone
> >> >>
> >> >> On Nov 27, 2012, at 10:24 PM, Routing Freak
> >> >> <routingfreak_at_gmail.com<mailto:routingfreak_at_gmail.com>> wrote:
> >> >>
> >> >>> Hi all
> >> >>>
> >> >>> In my customer core network where we had a heated about wither OSPF
> or
> >> >>> ISIS and finally ISIS won the race for the core IGP due to some
> >> >>> business decision and now my problem here is that when i was
> designing
> >> >>> the network with one large ISIS area with all the linka s L1,
> everyone
> >> >>> opposed me to not to configure L1 and go for L2.
> >> >>>
> >> >>> I know that L1 is within single area and L2 can be connected across
> >> >>> areas and also within a single area and it carries all the routes
> >> >>> within L1 and L2.
> >> >>>
> >> >>> But in my design , i have single large area with all links as L1,
> what
> >> >>> is the problem in that, L1 or L2 it should be the same.
> >> >>>
> >> >>> I didnt understood what is the logic behind the fact that L1 should
> >> >>> not be used and L2 should be used.
> >> >>>
> >> >>> I thought may be when they are forming more areas, then l2 makes
> >> >>> sense, but they r not going to expand the site with another area, so
> >> >>> why not going for
> >> >>> L1 will suffice the requirement .
> >> >>>
> >> >>> L1 is within one single area and doesnt know any other routes of
> other
> >> >>> area
> >> >>>
> >> >>> L2 router is one where all the areas merge and exchange routes in
> one
> >> >>> separate area. It can be any area and not area 0 and just all the
> >> >>> routers in that particular area should be running L2 adjacency with
> >> >>> each other.
> >> >>>
> >> >>>
> >> >>> In one large area, which is better L1 or L2. Any ISIS Experts, be
> sure
> >> >>> to reply to this.
> >> >>>
> >> >>>
> >> >>> Blogs and organic groups at http://www.ccie.net
> >> >>>
> >> >>>
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> >> >>
> >> >>
> >> >>
> >> >>
> >> >>
> >> >>
> >> >>
> >> >>
> >> >>
> >> >>
> >> >> --
> >> >> Shiran Guez
> >> >> MCSE CCNP NCE1 JNCIA-ENT JNCIS-ENT CCIE #20572
> >> >> http://cciep3.blogspot.com
> >> >> http://www.linkedin.com/in/cciep3
> >> >> http://twitter.com/cciep3
> >> >>
> >> >>
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> >> >>
> >> >>
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Received on Wed Nov 28 2012 - 14:02:58 ART