Re: OSPF Problem

Thanks a lot guys for the reply

Now understood it thoroughly

On Tue, Jul 5, 2011 at 9:52 PM, mazhar minhas <mmgnoc_at_hotmail.co.uk> wrote:

> hi,
>
> Dear all
>
> Sham link and virtual are both Virtual in natures, but they work in
> differently.
>
> i hope you know about virutal links already .
>
> Sham link is related to MPLS concept.
>
> where you have to 2 x CE and connected to and 2 x PE. OSPF is PE - CE
> protocols running between PE and CE as well.
>
> What happens in this case if you are running OSPF across on the CE as well
> just to use the Backup?
>
> you can't use MPLS links across for this site, Reason
>
> Intraarea (o) is prefer over Interarea (IA), this means that MPLS can't be
> used
>
> because when we redistribute OSPF into BGP and from BGP back to OSPF they
> appear on the other side as IA, but if site has same routes via Intraarea
> (o) it would prefer the others link and not the IA routes (MPLS)
>
> but our requirement is to use MPLS across.
>
> here we make sham link across 2 PE, and this way we make sure that site use
> MPLS and not the directly connected links.
>
>
> http://www.cisco.com/en/US/docs/ios/12_2t/12_2t8/feature/guide/ospfshmk.html
>
> so the only in Sham links they prefer IA routes over O roues.
>
> i hope that would be helpful
>
> mazhar
>
> CCIE (RS & SP)
>
>
>
>
>
>
>
>
> > Date: Tue, 5 Jul 2011 21:26:53 +0530
> > Subject: Re: OSPF Problem
> > From: routingfreak_at_gmail.com
> > To: bhmccie_at_gmail.com
> > CC: ccielab_at_groupstudy.com
>
> >
> > hmm Thanks Hammer for ur valuable info
> >
> > I m looking for some GREAT's response
> >
> > On Tue, Jul 5, 2011 at 9:23 PM, -Hammer- <bhmccie_at_gmail.com> wrote:
> >
> > > **
> > > There are certainly more qualified folks here that may speak up but I
> do
> > > not look at it as extending a non backbone link. I look at it as a
> method to
> > > enforce more preferred (the cloud) routing between PEs. I look at it
> more or
> > > less as a pvc or a tunnel between the PEs. I'm sure that's not the best
> way
> > > but it works for me to think thru it.
> > >
> > > -Hammer-
> > >
> > > "I was a normal American nerd"
> > > -Jack Herer
> > >
> > >
> > >
> > > On 07/05/2011 10:48 AM, Routing Freak wrote:
> > >
> > > Hey Hammer, Good one
> > >
> > > But stilll I hava a problem, Is sham link extending ur non backbone
> link to
> > > the backbone link ( ie ur Super Backbone)
> > >
> > >
> > > On Tue, Jul 5, 2011 at 9:12 PM, -Hammer- <bhmccie_at_gmail.com> wrote:
> > >
> > >> Dude I didn't mean to simplify it. You were asking for the difference
> > >> and I thought a clearer explanation might have helped. I don't look at
> these
> > >> as being in the same realm and that's why maybe I am missing where you
> are
> > >> confused. Yes, V-Links are an "extension" of area 0. Whereas sham
> links are
> > >> used to "bridge" together multiple PEs in the same MPLS VPN backbone.
> The
> > >> sham link gets you past the default OSPF rules for selecting
> intra-area
> > >> routes instead of inter-area. The sham link also allows the sites to
> > >> communicate over the MPLS VPN instead of via any external paths not
> provided
> > >> via the cloud. Does that help?
> > >>
> > >> -Hammer-
> > >>
> > >> "I was a normal American nerd"
> > >> -Jack Herer
> > >>
> > >>
> > >>
> > >>
> > >> On 07/05/2011 10:33 AM, Routing Freak wrote:
> > >>
> > >> Dude i know how to configure ospf sham link . I need to know about the
> > >> difference technically speaking differences
> > >>
> > >> Share some theory behind both, What r the similarities and what r the
> > >> differences?
> > >>
> > >>
> > >> On Tue, Jul 5, 2011 at 8:55 PM, -Hammer- <bhmccie_at_gmail.com> wrote:
> > >>
> > >>> This helped me understand sham links better a while back....
> > >>>
> > >>> http://blog.ipexpert.com/2010/01/20/introduction-to-ospf-sham-link/
> > >>>
> > >>> -Hammer-
> > >>>
> > >>> "I was a normal American nerd"
> > >>> -Jack Herer
> > >>>
> > >>>
> > >>>
> > >>> On 07/05/2011 10:17 AM, Routing Freak wrote:
> > >>> > Hey mates,
> > >>> > I have a little confusion. What is the difference between Sham link
> and
> > >>> > Virtual Link?
> > >>> >
> > >>> > I know that Virtual Link is to extend ur backbone
> > >>> > Sham link is used as a false link between two PE's . Is it
> extending
> > >>> ur
> > >>> > Area to other area and fool them that they r in the same area??
> > >>> >
> > >>> > Because Sham link mainly used as a virtual cable which sends Intra
> area
> > >>> > LSA's ( which is the Type 1 LSA's) to other PE .
> > >>> >
> > >>> > What does exactly the difference betwen Virtual links and Sham
> links
> > >>> >
> > >>> >
> > >>> > Blogs and organic groups at http://www.ccie.net
> > >>> >
> > >>> >
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Received on Tue Jul 05 2011 - 22:08:58 ART