Author Archives: pim

Configuring OSPF for IPv6 on Cisco IOS

Posted on 25 October 2012 by pim

1. Enable IPV6: R4(config)# ipv6 unicast-routing 2. Supply interface fa0/0 with an IPV6 address: R4(config-if)# ipv address 2001:0:0:1::/64 eui-64 3. Configure an IPV6 OSPF routing process 110: R4(config)# ipv6 router ospf 110 Here manually supply a router id: (optional if … Continue reading →

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The OSPF DR / DBR election algorithm within IOS

Posted on 24 October 2012 by pim

The OSPF DR / BDR router election algorithm within IOS The OSPF BDR / DR election is only performed for SWITCHED networks, not on serial networks. The whole idea of having a DR is to minimise the flooding of LSA’s … Continue reading →

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A smart advise when designing high-end networks

Posted on 24 May 2012 by pim

I didn’t check where this quotes originates from, but is very true all the same:   “Switch where you can, route where you must”

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The NAT / PAT architecture according to Cisco

Posted on 16 May 2012 by pim

 

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RIP and hold-down timers

Posted on 14 May 2012 by pim

Click here for the PDF file that explains the algorithm: hold-down-timer-algorithmn1

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The EIGRP feasibility conditions

Posted on 14 May 2012 by pim

A Cisco IOS EIGRP feasible successor router can become successor provided the following criteria are met: 1. ADfeasible successor < FDsuccessor

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Router summurization in contiguous and discontiguous networks

Posted on 14 May 2012 by pim
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Explanation by examples: virtual routing tables (vrf)

Posted on 8 May 2012 by pim

1. Create 3 virtual router forwarding (vrf) table entries In the following example we are going to setup VRF tables and see how they can be applied to ordinary routers. MPLS is not used in this example, which make the … Continue reading →

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The Spanning Tree (SPT) Algorithm explained in detail

Posted on 7 May 2012 by pim

Spanning Tree Protocol SPT Note: The phrase “bridge” can be read as switch as well in the explanantion below. 1. Elect the Bridge with the LOWEST Bridge – ID (BID = Priority. MAC) as root bridge. The default Priority is … Continue reading →

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How to recover a Cisco 2600 router and restore IOS

Posted on 18 April 2012 by pim

Boot in Rommon by interupting the boot of the router via a SEND BREAK on the Serial Console during the boot. rommon 13 > TFTP_FILE=c2600-adventerprisek9-mz.124-16.bin rommon 14 > IP_ADDRESS=10.1.1.3

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