Foreword
Loosely translated, Heraclitus says, “Change is the only constant.” Change is one of the hallmarks of life – growth, repair, adaptation. Networks, whether those of service providers, enterprises, or data centers, are not different – they grow, they change: a new port here, a software upgrade there, a customer tweak elsewhere, accompanied by the perennial quest for higher bandwidth, broader services, increased scale, and ultimately, greater utility. These changes, small or large, accrete almost unnoticed, until today's network is unrecognizable from the network a few years ago. These changes are not always planned; they tend to be driven by short-term tactical considerations rather than longer-term strategy. Thus, it is no surprise that the cumulative effect is not always desired – it is what it is.
Network Mergers and Migrations: Junos® Design and Implementation is not about managing the daily changes that occur in networks. Rather, it is about tectonic shifts in networks: how to plan them, how to lay the groundwork for them, and most importantly, how to bring them to fruition effectively and safely. Such tectonic shifts may be needed for a number of reasons:
- as a “course correction” of the accumulation of the smaller changes mentioned above;
- to adapt to significant technological evolution, such as cloud computing;
- to accommodate ...
