From: Pavel Bykov (slidersv@gmail.com)
Date: Fri Jan 23 2009 - 15:21:35 ARST
Because otherwise you wouldn't be able to reroute traffic from the right
distribution switch to the access immediately - you would have to wait for
IGP convergence.
If ptp link between distribution switches is WITHIN the range that is being
summarized, you don't wait for a convergence, and use feasible successor
route INSTANTENEOUSLY
On Wed, Jan 21, 2009 at 10:30 PM, ISolveSystems
<support@isolvesystems.com>wrote:
> I am reading the campus network design guide.
>
>
> http://www.cisco.com/en/US/docs/solutions/Enterprise/Campus/HA_campus_DG/hacampusdg.html
>
>
>
> See the paragraph below. Why does the address space selected for the
> distribution-to-distribution link must be within the address space being
> summarized to be effective?
>
>
>
> "Because the distribution nodes send summarized information towards the
> core, an individual distribution node does not advertise loss of
> connectivity to a single VLAN or subnet. This means that the core does not
> know that it cannot send traffic to the distribution member where the link
> has failed. Adding an L3 link between the distribution switches allows the
> distribution node that loses connectivity to a given VLAN or subnet to
> reroute traffic across the distribution-to-distribution link. The address
> space selected for the distribution-to-distribution link must be within the
> address space being summarized to be effective."
>
>
> Blogs and organic groups at http://www.ccie.net
>
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-- Pavel Bykov ---------------- Don't forget to help stopping the braindumps, use of which reduces value of your certifications. Sign the petition at http://www.stopbraindumps.com/Blogs and organic groups at http://www.ccie.net
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