PCDVD數位科技討論區 - 中華電信MOD無線化遇到瓶頸

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我對 multicast over 11g

很懷疑這架構

之前測過 , 在公司網路 600台 PC 的網芳的 multicast , 就
讓 wireless AP 的 wireless 無法回應 ping
multicast 流量大慨才 0.1~0.2 Mbps

另外電力線網路

有人用 85Mbps , 會有問題 !
用 200Mbps , 較保險 , 不過這也是目前最快的電力線網路標準

如果真的要 MOD無線化

選 11n 看看,

不然只是不要網路線
還有電力線網路 200Mbps 可以選

上上個月裝 MOD , 就去買電力線網路 200Mbps

一對 3000 ~ 4000 元

引用:

作者idleic2

我對 multicast over 11g

很懷疑這架構

之前測過 , 在公司網路 600台 PC 的網芳的 multicast , 就
讓 wireless AP 的 wireless 無法回應 ping
multicast 流量大慨才 0.1~0.2 Mbps
snipped....

600台PC網芳的multicast讓wireless AP無法回應ping和此時能不能正確處理packet forwarding不一定是同一回事(i.e. packet forwarding是L2部份負責的,通常是H/W based,而ping是L3的,通常是SoC跑firmware的結果----SoC此時跑不動不代表L2 packet forwarding也一定跑不動:flash: ),不過讓600台PC塞在同一LAN上也實在有點誇張就是了:ase....BTW,鵝在Mobile01上看到有網友指出802.11要求對broadcast/multicast以基本速度來傳送(i.e. 1Mbps:ase),不過鵝沒仔細看過802.11的文件,不知是不是這個原因就是了:confused: :confused: ....

那電力線要選homeplug av 還是 DS2
各位大大有推荐的嗎?

引用:

作者noritsu

那電力線要選homeplug av 還是 DS2
各位大大有推荐的嗎?

homeplug av

照接線圖接

無線AP 要設定為一般AP SWITCH 模式 (關閉DHCP 自動配發IP 模式)

無線網路卡都改為預設

應該就OK 不過會有缺點

就是必須使用撥號連線填入帳號密碼在點播接上網(若數據機已經有DHCP功能就不用)

FYI:以下引自Multicast in 802.11 WLANs: An Experimental Study....

引用:

Multicasting video instead of streaming individually each video results in a much more efficient use of the shared wireless medium. Whereas all these new applications are very likely to appear soon with upcoming WiMAX or DVB-H enabled devices, the IEEE 802.11 standard does not comply with multicast data requirements. In particular, the current MAC layer sends multicast packets in open-loop as broadcast packets, i.e., without any possible acknowledgements.
This open-loop transmission mechanism causes three main problems. First, without feedback mechanism, it is not possible to adapt the contention window according to the network state, as it is done with regular point-to-point connections. Consequently, multicast achieve a higher priority than concurrent unicast and the network may become severely congested and could collapse. Second, it is not possible to adapt the physical (PHY) transmission rate to the channel characteristics, so the packets are broadcast over the wireless medium at one of the rates included in the
basic rates set. Third, there is no way to retransmit lost packets at the MAC layer, so the transmission is more lossy than for unicast , which degrades performance of the multicast application.

看來802.11先天上還真是不適合直接拿來送multicast就是了,不過有些AP有強調適應multimedia的部份,不知是不是有針對這些部份避開802.11的先天限制:confused: :confused: ...