[課業] 電腦網路/IP位址-聚合

作者: lena80379 (小豆芽) 看板: Examination
標題: [課業] 電腦網路/IP位址-聚合
時間: Wed Apr 21 16:36:22 2010

1.考試科目：電腦網路


2.章節名稱or篇名(單元關鍵字)：IP位址


3.目前參考用書or考古題出處：電腦網路Tanenbaum第四版 第五章習題第42題

  題目：The set of IP addresses from 29.18.0.0 to 19.18.128.255 has been
        aggregated to 29.18.0.0/17. However, there is a gap of 1024
        unassigned addresses from 29.18.60.0 to 29.18.63.255 that are
        now suddenly assigned to a host using a different outgoing line.
        Is it now necessary to split up the aggregate address into its
        constituent blocks, add the new block to the table, and then see
        if any reaggregation is possible? If not, what can be done instead?

  解答：It is sufficient to add one new table entry: 29.18.0.0/22 for the
        new block. If an incoming packet matches both 29.18.0.0/17 and
        29.18.0.0./22, the longest one wins. This rule makes it possible
        to assign a large block to one outgoing line but make an exception
        for one or more small blocks within its range.


4.想問的內容：

        第一行19.18.128.255應該是29.18.128.255吧


        答案是29.18.0.0/22 那這樣29.18.60.0~29.18.63.255不就不包含在裡面了?


5.想法：

        我想的是29.18.60.0/22耶XD......


  感謝指教^^