Network Planning¶
When building a network, a solid plan can save both time and make your network more efficient. Using generalized strategies for things like which interfaces should connect where or which IPs to use. These are typically completely up to you to choose, as an example:
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The interface closest to the users that uses the lowest index of interfaces.
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The interface closest to the internet uses the higest index of interface.
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The remaining interfaces use indexes counting upward or downward, depending on if they point toward users or toward the wider network.
Applying such a strategy won't speed up the process in the short term, but having uniform strategies in configuring the router helps greately when troubleshooting at later stages.
IP-planning¶
IP-planning consists of three steps. Firstly, set principles or policies for how you want to allocate IP addresses within your network. Secondly, go through the process of subnetting to dedicate IP-address ranges for your various networks. Lastly, apply the IP-addresses to each of the interfaces of your network devices.
As with planning the interface usage, having a clear and documented IP-plan may assist greatly in troubleshooting, but will also help with the initial setup, alleviating mistakes and removing the need to do things over if you've made a mistake. A well thought out IP-plan will also cover expansion of the network, to accomodate changes that might occur in network needs. An example of a network plan may be a table, for instance:
| Device | Interface | IP Address | Subnet Mask | Connected to |
|---|---|---|---|---|
| Router 1 | eth0 | 10.10.240.0 | 24 | Router 3: eth0 |
| Router 1 | eth1 | 192.168.0.1 | 31 | Router 2: eth0 |
| Router 2 | eth0 | 192.168.0.0 | 31 | Router 1: eth1 |
| Router 2 | eth1 | Not in use | N/A | N/A |
| Router 2 | eth2 | 242.155.64.33 | 31 | Router 4: eth1 |
IP-routing planning¶
Planning how you want to apply routing to a network is helpful to do early. By planning which routing protocols you want to use and how you want to apply them, you have a better background to determine and efficient IP-plan. For instance, if you want to apply BGP, but don't want to share some addresses/networks externally, it could be beneficial to give the non-shared addresses similar IP-addresses to allow for easier filtering of these addresses when applying BGP. This eases your configuration of the network, which may both save time and alleviate errors that you may encounter.
Redistribution Pitfalls¶
Redistribution is the process of exchanging routing information between routing protocols. One should avoid advertising the same network multiple times via different routing protocols, as this may cause continuous loops that prevent packets from reaching their intended destination. It can cause inconsistent routing and poor path selection, as well as result in a larger than neeeded routing table.