From: Joseph Brunner (joe@affirmedsystems.com)
Date: Thu Sep 13 2007 - 17:04:34 ART
Did you see my best practice page on dmvpn?
http://affirmedsystems.com/gotdmvpn.html
You should configure a 2-hub configuration on the spokes. Hub #2 is
configured as a spoke of Hub #1. NHRP and EIGRP take care of the failover.
Hub #1 and Hub#2 play in the same private ip space for the tunnel interfaces
with the spokes... if you have some extra cash and a secondary isp at the
spokes make hub #3 a spokes second tunnel interface destination. The
secondary (complete isp backup dmvpn from the spokes to Hub#3) tunnel
interface is sourced from the backup isp interface. This tunnel is only
active when the default fails from isp1 to isp2 at the spokes.
-Joe
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
sheherezada@gmail.com
Sent: Thursday, September 13, 2007 3:46 PM
To: Cisco certification
Subject: OT: DMVPN limitation
Hi,
Sorry for this off topic, but maybe some of you can redirect me to an
useful resource.
I am planning to deploy from scratch a DMVPN setup and want to
understand the limitations regarding the number of tunnels.
In short:
- 500 spokes - Cisco 877, no physical backup circuits
- 2 hubs, daisy chaining. Basically, I want to ensure that a hub is
always available.
- 3-4 Mbps aggregate bandwidth (that's right, each spoke user has only
a terminal emulator, so it's low bandwidth consumption)
I am planning to use Cisco 3845 for the hubs, but as far as I can read
on the Internet, even a Cisco 7200 with NPE-G1 is limited to 350 DMVPN
tunnels?! Is this because of CPU usage when a major re-convergence
occurs or something else relative to EIGRP? I can't imagine using a
larger box only for several megabits of traffic...
Thanks,
Mihai Dumitru
CCIE #16616 (SP, R&S)
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