David Sudjiman

R2(config)#int lo0
R2(config-if)#ipv addr fec0::2:1/112
% FEC0::2:1/112 can not be configured on Loopback0, overlapping
R2(config-if)# ipv addr FEC0::12:3/112
% FEC0::12:3/112 can not be configured on Loopback0, overlapping
R2(config-if)# ipv addr FEC0::222:1/112
R2(config-if)# ipv addr FEC0::2:1/112

R2(config-if)#do sh ver | i IOS
Cisco IOS Software, 3600 Software (C3640-JS-M), Version 12.4(18), RELEASE SOFTWARE (fc1)

Why am I getting these overlapping errors?

Arden Packeer. CCIE #20716
http://ardenpackeer.com/blog/ccie-20716/
Victor Cappuccio. CCIE Number: 20657
http://vcappuccio.wordpress.com/2008/04/30/ccie-number-20657/
Ethan Banks. CCIE #20655
http://www.cciecandidate.com/?p=412
and
Triple CCIE
Joe Harris. CCIE # 6200 (R&S, Security & SP)
http://6200networks.com/2008/04/27/i-passed/

This is the simplest network type for OSPF. Two routers connected via point-to-point link. For this particular network, there is no need to have DR and BDR. Why, because each router will sending updates to each other and having DR and BDR will not change the situation. Each router will send multicast hello packets using [...]

Partial-mesh or star network topology.
One IP Subnet.
Hello Timer 30 seconds.
Manual adjacency, no DR/BDR elected.

Partial-mesh or star network topology.
One IP Subnet.
Hello Timer 30 seconds.
Automatic adjacency, no DR/BDR elected.

Non Broadcast Multi Access (NBMA) - RFC 2328 Standard

Full or partial-mesh network topology.
One IP Subnet.
Hello Timer 30 seconds.
Manual adjacency, DR/BDR elected.

From the previous example, we see that we’re using broadcast mode on NBMA network. What if we don’t want to use broadcast mode since it’s a non-broadcast network, anyway?

Configuring OSPF network can be cumbersome considering the requirement for each router to send update to other routers to create the same topology table. Obviously, in the big network with more routers, there will be more multicast updates to any routers which mean more traffic. This is where OSPF area comes into play. Rather than [...]

Shortcut them all
This is an old skool but just in case you don’t know it. You can use shorter command on your Cisco router or switch.

router#copy running-config startup-config
Destination filename [startup-config]?
Building configuration…
[OK]
router#copy run start
Destination filename [startup-config]?
Building configuration…
[OK]
router#wr
Building configuration…
[OK]

router#show ip interface brief
Interface [...]

Taken from http://www.cisco.com/en/US/docs/ios/iproute/configuration/guide/irp_bgp_link_band.html
The link bandwidth extended community attribute is a 4-byte value that is configured for a link that on the demilitarized zone (DMZ) interface that connects two single hop eBGP peers. The link bandwidth extended community attribute is used as a traffic sharing value relative to other paths while forwarding traffic. Two paths are [...]

Download full size of network topology
This is my BGP lab I’ve created on dynamips. I don’t have the time to explain in details why I configure it this way. This is actually part of my BGP/CCIP study. So, don’t expect you will find BGP/CCIE level on this lab.
This lab consists:
- Multihoming to multi ISP
[...]