Category Archives: Cisco Networking

For courses, entertainment and educational purposes.

A Cisco FLEXLINK STUDY

A study in Flexlinks.. FLEXlink-study

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Router Failover Configuration with BGP and NAT with two ISPs

This is for the more hard core Cisco IOS users: With multi-homed BGP you can let your router failover internet service providers. You can track their availability with SLA, or simply let BGP do its thing. The thing that had … Continue reading

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The Cisco – IOS CLI menu structure

IOS-CLI-Menu-structure

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An STP example within GNS3

Configuring a Spanning Tree in GNS3: ———————————— I found that configuring the SPT  was always a bit vague due to the fact that dynamips / dynagen emulate Cisco IOS Routers, not switches. I didn’t find a simple example that tells … Continue reading

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Subnetting exercises 2 of 2

2. A network administrator has been provided with the following block of class A IP addresses: 12.24.0.0/21. He has been asked to create at least 3 subnets with equal size netmasks, and the number of the hosts per subnet are … Continue reading

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Subnetting exercises 1 of 2

1. A network administrator has been provided with the following Class B block of IP addresses: 172.16.0.0/16 It is his task to subnet this Classful network to have (at least) 9 subnets available and maximize the number of hosts available … Continue reading

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Configuring OSPF for IPv6 on Cisco IOS

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

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

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

Click here for the PDF file:  NAT-drawing

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