Terry,

 

On number 3.  The hub should have ip next-hop-self.  Which is the default
command.  This makes sure the next hop is known via the hub which it will
have a CEF entry for.  If you change the default behavior then the route
will be known via a next-hop that will not be in the RIB thus an incomplete
entry in the CEF Table.  The purpose of Phase 3 is to prevent traffic from
being sub-optimally process switched.

 

Regards,

 

Tyson Scott - CCIE #13513 R&S, Security, and SP

Technical Instructor - IPexpert, Inc.

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From: [email protected]
[mailto:[email protected]] On Behalf Of Terry Little
(terlittl)
Sent: Monday, April 05, 2010 10:58 AM
To: CCIE Sec
Subject: [OSL | CCIE_Security] DMVPN Phase 3 Clarification

 

OK,

 

Phase 3 is all about the ip nhrp redirect and ip nhrp shortcut commands. And
I am pretty sure that I understand it all, but wanted a bit of confirmation.

 

1.      The shortcut command is REQUIRED on the spokes, optional on the hub.
I can't figure out what it would do on the hub, but it doesn't hurt
anything.

2.      The redirect command is REQUIRED on the hub, recommended on the
spokes. Leaving it off the spokes doesn't break anything, it just leaves
some routes in a complex DMVPN network sub-optimal. 

3.      Finally, the must not have "NO next-hop-self" or else the spoke to
spoke tunnels do not get built. It still works, but the traffic is via the
hub.

 

Did I miss anything??

 

Terry Little 

[email protected]
Phone: +1 425 468 1057     

Mobile: +1 425 894 4109

Cisco Systems, Inc.

Network Consulting Engineer
World Wide Security Services Practice
Cisco.com - http://www.cisco.com

 

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