Networks can be really simple but we insist on making it complex !
If you are adding new technologies onto an existing network, these sorts of questions should be kept in mind:
1. What can be broken?
You need to make sure, when you add new protocols or technologies on to an existing network, you will not break anything. For example, you have an IPv4 network and want to add IPv6 as well. If your hardware cannot handle the additional IPv6 routes,IPv4 traffic is dropped as well.
Or if you have QoS and you prioritize Voice traffic, without having CAC (Call Admission Control), in case of congestion, new voice calls affect the quality of all existing voice calls.
Last but not least, as an example, if you migrate IS-IS flat design to multi level IS-IS design , you break the MPLS LSPs. Though this can be seen as a migration, I wanted to highlight here.
Does this technology affect others technologies/protocols in the network?
2. What does this technology provide? Is it really necessary?
It is a profound and necessary truth that the deep things in science are not found because they are useful; they are found because it was possible to find them !
Are you looking hard enough to find the usefulness of the technology which you consider to add to your network ?
For example, If you have enough bandwidth in your network, do you really need Quality of Service ? Most backbone/core networks as of 2017, have DWDM optical network infrastructure on their core network. Which mean plenty of capacity with a very cheap price. Thus, they don’t want to deal with QoS queuing etc. No need to add this new technology for them.
Another example, MPLS Traffic Engineer. You might be considering to implement MPLS Traffic Engineering but if you would arrange your routing protocol metric well, would you need MPLS Traffic engineering at all? Check my this post on this discussion.
3. What are the alternatives of these technology or protocol?
One should always look for a possible alternatives, and provide against it !
You need to know the alternatives of the networking technologies. Without solid knowledge about them, you cannot compare.
If you cannot compare, then how for example you can decide whether OSPF or IS-IS is better for your network ?
I have plenty of technology comparison charts which will help you to understand the pros and cons of many common networking technologies.
4. Which additional information do you need to deploy this technology/protocol?
If you have been following this blog for some time, you probably know that all networking protocols and technologies interact with each other.
You enable a function in the WAN, it affects the latency from LAN to Datacenter.
For example, you may want to provide MPLS VPN service, but knowing only MPLS is not enough to provide MPLS VPN service.
5. How much complexity new protocols will put on to existing network ?
Every new technology adds some amount of complexity, so consider complexity vs. the benefits of the technology tradeoff! As it is mentioned above, do you really need to deploy MPLS Traffic Engineering for better utilization or with the IGP protocol metric design could you achieve the same goal?
Don’t use a lot where a little will do the job !