Design considerations for network mergers and acquisitions

Network mergers and acquisitions are processes that can be seen in any type of business.

As network designers, our job is to identify the business requirements of both existing networks and the merged network and find the best possible technical solutions for the business.  

There are many different areas that need to be analyzed carefully.

Wrong business requirement gathering and design analysis, definitely lead to catastrophic failures.

Business and network analysis and technical information gathering are the key steps and there are many questions that need to be asked and answered should be well understood.

Network mergers and acquisitions are also called Network integration.

Below are the key points for any type of network mergers and acquisitions projects.  


Business analysis and information gathering

Applications of the company, at least the business-critical applications should be understood and analyzed very well.

What are the capabilities of these applications and what are the requirements from the existing network? (Packet loss, jitter, delay, application traffic flow, security and QoS requirements, and so on).

Basically in this step, we analyze the current infrastructure of the companies. IP addressing scheme, Application requirement, physical topology gathering, business future growth forecast analysis, security, QoS, Multicast, OAM and management infrastructure capabilities, and information should be gathered.

What type of WAN, LAN, and DC infrastructure each network is using, Is any VPN solution deployed on the WAN, is there a traffic engineering requirement on WAN or DC, and Is IPv6 supported by any of the companies? Is there any single point of failure and what will be the high availability requirement of the merged network?

What is the convergence time of the network and what is the required convergence time of any single component failure? (You shouldn’t design the network for multiple failures)

As you can see there are so many questions that should be asked and noted during the business analysis. This is the most time-consuming step of any network design but definitely worth doing it properly to avoid any future problems and have the best network design.

Analyzing the design for network mergers and acquisitions is not different from analyzing the design for the greenfield network. Application and business requirement is always the most important, and technology is second. Alternative technologies always can be found.  


Where will be the first place in the network for the merger?

When two networks merge, generally two networks are connected through their core network component. If there is any overlapping issue, for example, IP Address, these should be fixed. Traditionally IP address overlap issue is fixed via NAT (Network Address Translation).

Physical location selection is very important. As you will see later in the post, some of the sites can be decommissioned for operational cost savings. After deciding the locations which will be used, by extending the current WAN connections companies can start to reach each other.   


What happens to the routing, IGP, and BGP? Is a “ship in the night” approach suitable or redistribution is better for routing protocol mergers?

One common routing protocol can run through both networks or if there are two different IGPs, redistribution can take place. If there is MPLS on the networks, any type of Inter-AS VPN solution can be deployed. In some Inter-AS MPLS solutions redistribution is not required.

Running common IGP is always better compared to dealing with redistribution. It is better for management, troubleshooting, convergence, availability, and for many other design objectives.  


Which type of security infrastructure will merged network support?

What are the existing security policy and parameters of each individual network? You should deploy a common security policy for the merged network. You should make sure the edge of the network is as secure as possible and the core of the network just should transport the packets.  


What are the Quality of Service Policies of the companies? Will the final merged network support Quality of Service or through bandwidth everywhere?

The quality of service policy of end-to-end networks should be deployed by understanding the applications of each individual company. That’s why understanding the applications which were analyzing the network task, is crucial. You should follow the best current practices for QoS design.

Some businesses don’t use QoS, especially on their core network. They generally have their DWDM infrastructure, so when they need extra capacity, they can provision it quickly and start using it. The reason why they don’t use QoS is simplicity. They want to keep their core network as simple as possible. This approach is seen generally in the Service Provider business.  


Will the merged network have IPv6?

IPv6 is unavoidable. There are many IPv6 business drivers for any type of business. If IPv6-only design is not possible for the merged company, at least IPv6 transition mechanisms should be understood very well and considered for the merged network.  


Does one of the networks require Multicast? Will the merged network support Multicast?

If Multicast is running on any of the companies, most probably merged network will require and benefit from the multicast deployment as well. PIM (Protocol Independent Multicast) and current multicast best practices should be understood and deployed based on the company's requirements. Some applications of the company may benefit from the special Multicast routing protocol deployment model such as PIM ASM (Any source multicast), PIM SSM (Source-Specific Multicast), or PIM Bidir (Bidirectional Multicast).  


What is the new capacity requirement of the merged network?

When two networks merge overall capacity requirement for edge and core networks generally changes. Understanding network capacity planning is key and network designers should understand the available methods for backbone and overall network capacity planning tools and best practices.  


How will be the merged network monitored? Do exist Network Management tools capable to support all the technologies/protocols of both networks?

Both companies may have different monitoring tools, application support might be different from their tools as well. Monitoring and management tools should be considered before the merger because tools should be able to support all applications, protocols, and technologies of the merged network.  


When you divest the network, where will the data centers be? Can you decommission any datacenter, POP location for cost optimization?

Some of the locations of the companies may overlap and some POP locations and/or datacenters, even Head Quarters can be decommissioned to reduce operational expenses. The physical topology of the companies should be understood well and if there is a cost or advantage of choosing a particular location, definitely needs to be considered.

This is definitely not the entire list for network mergers and acquisitions, but you should at least start your design with these questions in your real-life design as well as in the design certification exams. In the CCDE exam, questions will be based on the above considerations mostly.

Further Study Resources on Network Mergers and Acquisitions

Network Mergers and Migrations book- Wiley

Network Integration Panel Discussion

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Orhan Ergun

Orhan Ergun, CCIE/CCDE Trainer, Author of Many Networking Books, Network Design Advisor, and Cisco Champion 2019/2020/2021

He created OrhanErgun.Net 10 years ago and has been serving the IT industry with his renowned and awarded training.

Wrote many books, mostly on Network Design, joined many IETF RFCs, gave Public talks at many Forums, and mentored thousands of his students.  

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