Re: Peer Group and Peer Template

Hi. Peer templates are a logical evolution of Peer groups.
There is a short description on Cisco about what Peer Tamples bring to the
template, including the most obvious limitations of the previous methods.
http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gt_bgpct.html#wp1027177
In summary, the evolution went from:
Peer Groups >to> BGP Dynamic Update Peer-Groups >to> Peer Templates
Some of the limitations of the previous include:
-All neighbors that shared the same peer group configuration also had to
share the same outbound routing policies.
-All neighbors had to belong to the same peer group and address family.
Neighbors configured in different address-families could not belong to
different peer groups.
-A neighbor can belong only to one peer group.
-Neighbors that belong to different address-families cannot belong to the
same peer group.
-Different sets of policies cannot be grouped and applied to a neighbor.

This largely reflect the experience.
I had definitely issues, especially on PEs, that peer-groups cannot be
combined, or used with neighbors with different AFs.

But that does not mean, that Peer-Templates replace Peer-groups.
Think of them as route-map and filter-list in BGP.
Filter-list applied AS_PATH based filter to a neighbor. And route-map can
accomplish the same and much much more. But you don't have to use route-map.

Maybe, in future, once the peer-groups become less popular, Cisco will
remove it from IOS.
But until then, people who are not restricted by peer-group limiations may
use those. And those that need advanced-functionality, or those progressive
engineers that see the benefit in using more flexible toolkit to be better
prepared for the future, may use peer-templates.

On Sun, Oct 16, 2011 at 8:49 AM, Routing Freak <routingfreak_at_gmail.com>wrote:

> Hi Raghava
>
> Thanks for the link dude. It has explained the various fleibilities of peer
> session and peer policy template. I am happy with the eamples but still not
> convinced about the usage of peer groups and peer templates. Where will
> they
> use peer session and where will they use peer group ?
>
> Still confused. I need some epert to chip in with a good eample
>
> Thank You
>
>
> On Sun, Oct 16, 2011 at 11:38 AM, Raghava Rao <raghava.rao85_at_gmail.com
> >wrote:
>
> > Refer to this, a good link posted here on --
> >
> > http://cciethebeginning.wordpress.com/2009/01/09/358/
> >
> > HTH
> >
> > //Raghava
> >
> >
> > On Sun, Oct 16, 2011 at 11:32 AM, Routing Freak <routingfreak_at_gmail.com
> >wrote:
> >
> >> Hi Ragahav,
> >>
> >> Peer group logic says that when u send a update to a particular neighbor
> ,
> >> u
> >> dont want to generate every single update packet to each and every
> >> neighbour
> >> . Its like a single packet which gets replicated and goes to each and
> >> every
> >> neighbor , which in turn saves ur CPU processing and ur bandwidth .
> >>
> >> As u said, Peer session is all about session parameters, what does it
> >> include, Peer group also does the same thing for a neighbor and their
> >> session. How is peer template different from peer group ?
> >>
> >> On Sun, Oct 16, 2011 at 10:35 AM, me you <anunda19_at_gmail.com> wrote:
> >>
> >> > There are limitation to peer group that templates are suppose to
> >> overcome.
> >> >
> >> > I don't remember all but peer groups have to have the same outbound
> >> > policies. I know there are more limitations.
> >> >
> >> > Rob
> >> >
> >> > On Sun, Oct 16, 2011 at 8:46 AM, Routing Freak <
> routingfreak_at_gmail.com
> >> >wrote:
> >> >
> >> >> Hi friends,
> >> >>
> >> >> I was reading and configuring peer groups and peer templates in BGP.
> >> But i
> >> >> cant really understand what is the basic difference between the two .
> >> It
> >> >> works the same? Why they came up with two different logics for Peer
> >> group
> >> >> and Peer templates
> >> >>
> >> >> Can anyone come up with some good points which can distinguish
> between
> >> >> them?
> >> >>
> >> >> Thank You
> >> >>
> >> >>
> >> >> Blogs and organic groups at http://www.ccie.net
> >> >>
> >> >>
> _______________________________________________________________________
> >> >> Subscription information may be found at:
> >> >> http://www.groupstudy.com/list/CCIELab.html
> >>
> >>
> >> Blogs and organic groups at http://www.ccie.net
> >>
> >> _______________________________________________________________________
> >> Subscription information may be found at:
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> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >
> >
> > --
> > Cheers!!
> >
> > Raghava Rao
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
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>
>
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>
>
>

-- 
Pavel Bykov
Blogs and organic groups at http://www.ccie.net