网络工程是一项复杂的系统工程，一般可分为网络规划、网络设计、工程实施、系统测试验收和运行维护等几个阶段。网络规划是在需求分析的基础上，进行系统可行性分析和论证，以确定网络总体方案。网络规划阶段任务完成之后转入下一阶段，即网络设计阶段。
【问题3】 在需求分析过程中应对已有网络的现状及运行情况作调研，如果要在已有的网络上做新的网络建设规划，如何保护用户已有投资(控制在100个字以内)
参考答案：在设计新系统时要充分考虑到利用已有系统的资源，让老系统纳入到新系统中运行，不要“推倒重来”。也可以把已有系统的设备降档次使用。
“A friend walks in when the rest of the world walks out.” Sometimes in life, you find a special friend: someone who changes you life just by being part of it; someone who makes you laugh until you can’t stop; someone who convinces( 使相信 ) you that there really is an open door just waiting for you to open it. This is forever friendship. When you're sad, and the world seems dark and empty, your forever friend lifts you up in spirits and makes that dark and empty world suddenly seem bright and full; Your forever friend gets you through the hard times, the sad times, and the confused times.If you turn and walk away, your forever friend follows; If you lose your way, your forever friend guides you and cheers you on; Your forever friend holds your hand and tells you that everything is going to be ok. And if you find such a friend, you feel happy because you need not worry. You have a forever friend for life and forever has no end.
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