Difference of 3Com 3C905 series NIC

這是之前遇到的狀況，因為當時還沒把網卡拍照存證，故現在補遺一下。

這是在前公司 (凱 x) 架設防火牆時發生的狀況。由於公司成立初期，百廢待舉，因此，也就以 PC + OpenBSD 來架設 firewall 以確保網路安全，也順便達到網段控管的目的。

一開始由於資源有限，因此，就以幾張 Realtek 8139 series 10/100 的網卡先頂著。但，有感於該網卡的耐受度和穩定度有限，因此，透過老闆的關係去找來幾張還不錯的 10/100 的網卡來用，以承受持續且較大的流量。

記得還在唸書時 (1996)，3Com 的 3C905 series 是當時的一時之選，因此，當時的 server 上這張卡是很常見的。如下面兩張圖:


3C905-TX


3C905B-TX

或許是時代的變遷，網路大興的影響，這個時期的網卡所使用的網路晶片已經不敷現時的需求了，因為流量已經不可同日而語了!

也因為如此，那陣子常會發生網路斷線。經過測試的結果發現那張卡到一定程度的流量就會掛點，唯一的辦法就是重開機。而它的耐受度比時下的 Realtek 8139 series 網卡還糟糕。上班時間總會給你斷個 1-2 次，主管都不得不來關切了。 =_="

在資源有限，問題無限的情況下，又苦於找不到 Intel 的 PRO/100 i8255x series 的時候，我無意間發現到下面這張卡 - 3Com 3C905C-TXM。


3C905C-TXM

經過仔細比較發現，這張卡所使用的網路晶片有別於較舊的兩款。3C905C-TXM 所使用的是 BROADCOM 5904 的網路晶片，而 3C905-TX 和 3C905B-TX 則是採用 LUCENT 40-03364 和 40-04834 的晶片。


BROADCOM 5904

經實際試用結果，不再有之前斷線的問題。連續使用一週後，系統也是相當的順暢。所以，就把所有的舊系列的網卡都用找來的 3C905C-TXM 替換掉了!

Comments

Post a Comment

Popular posts from this blog

How to construct a B+ tree with example

Image
A B+ tree contains n-1 search key values K1K2…….Kn-1 and have n pointers.   In a B+ tree the data are ordered  sequentially.  The leaf node may hold up to n pointers and must hold at least N/2 pointers. The root node must hold at least two pointers, unless the tree consists of only one node.  Now we construct a B+ tree. Construct a B+ tree for the following set of key values: (2,3,5,7,11,17,19,23,29,31) Assume that the tree is initially empty and values are added in ascending order. Construct a B+ tree where the pointer number is Four. Solution: When a node exceeds n-1 search key value then we split it into two nodes. First node contains (ceiling(n-1)/2) values.  2 nd node contains remaining node. Copy the smallest search key value of the second node to the parent node. Let's start, we know each node has N pointer and has N-1 search key values. In our example pointer number is 4, so the search key value is 4-1=3. So each node has 4 pointers and 3 search key value. The first node i
Read more

How to show only month and year fields in android Date-picker?

Image
Android default DatePicker show day/month/year fields but you have to customize this DatePicker as your requirements. Suppose that you want to show only month and year fields in android datepicker . To do this, you have to customize the Dialog DatePicker source code but it is not an easy task. In this tutorial I will show you a tricky way to solve this problem. Lets see how to show only month and year field in android DatePicker as a dialog.   Step to show only month and year fields in android date-picker: Some days ago I got this same problem and here I am trying to explain this in a sequential manner. I want to show a dialog datepicker when user click on an EditText. So if user click on EditText, A dialog datepicker will be invocked and it will show only month and year fields. To do this, at first we have to create a xml layout to hold the EditText fields. So create an android project and name it DatePickerExample. In the main.xml file just try to write this simple code.  main.xml
Read more

Visitor Counter Script Using PHP

Image
If you have noticed that many websites display their total numbers of visitors.In this tutorial I am going to explain you how to create a simple visitor counter using php. For this, 1) Create one table called “visitor_counter” in your database. 2) Create file named “counter.php”. Step1: Creating “visitor_counter” Table CREATE TABLE `visitor_counter` ( `counts` int(10) NOT NULL default '0' ) Step2: Creating “counter.php” File <?php  // Database Details $host="localhost"; $username="root"; $password=""; $db_name="test"; $tbl_name="visitor_counter"; // Connect to server and select database. mysql_connect("$host", "$username", "$password")or die("cannot connect to server "); mysql_select_db("$db_name")or die("cannot select DB");  $sql="SELECT * FROM $tbl_name"; $result=mysql_query($sql); $rows=mysql_fetch_array($result); $counter=$rows['counts']; // se
Read more