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!

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