From: Andrew B. Caslow (abcaslow@netmasterclass.net)
Date: Sat May 07 2005 - 07:21:50 GMT-3
Dennis,
This virtual-link is configured over the ISDN link for backup/redundancy
purposes. If the Frame-Relay link between R1 and R2 goes down completely, R2
would lose its connection to Area 0. By using the ISDN link between R1 and
R2 and by configuring a virtual-link over this ISDN link (the ISDN link is
in OSPF Area 12), R2 can reach OSPF Area 13 link residing between R1 and R3.
To get a much better explanation of this issue download the DOiT Scenario 3
Answer Key on the NMC CCIE Preparation Web Portal and go to pp 23-24. There
is an explanation and a nice little diagram describing this very issue.
If you have any problems accessing the answer key or navigating the NMC CCIE
Preparation Web Portal, please let me know.
I hope this helps.
Best regards,
-Bruce Caslow CCIE #3139
NetMasterClass, LLC
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Dennis J. Hartmann
Sent: Friday, May 06, 2005 9:05 PM
To: 'Bob Sinclair'; ccielab@groupstudy.com
Subject: NMC #3
I'm having a hard time figuring out why NMC scenario #3 calls for a
virtual link for area 12 when area 12 is connected to the backbone area on
both R2 and R2.
Is there a rule that OSPF areas can only have one connection to the
backbone area (one ABR)?
Is this because R1 in this scenario connects Area 13, area 0, and area
12 and this violates OSPF connectivity rules?
Please advise.
Sincerely,
Dennis J. Hartmann
White Pine Communications
CCSI#23402/CCIP/CCNP/CCDP/CCNA/CCDA
Cisco IP Voice Support & Design Specialist
Cisco Optical, VPN & IDS Specialist
MCSE
This archive was generated by hypermail 2.1.4 : Fri Jun 03 2005 - 10:11:56 GMT-3