Learning IOS and JUNOS

  我的第一本 iBook 封面設計，希望可以順利完成…但是看來在台灣要直接從Apple上架販售有一定的難度，可能還是得先找傳統出版社幫忙才行

在ICND1 Vol.1 P.1-167 提到了一個我沒有注意到的SFP規格(1000BASE-BX10-D/U)，原來現在可以利用一蕊的Fiber同時提供傳送及接收的方向，很久以前，在這種規格尚未出現之前，我們通常會使用一種fiber transceiver來達成這種目標，主要的原因就是為了可以減少fiber蕊數的使用，現在看來是把這種技術直接整合進了SFP中。 參考資訊： http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6577/product_data_sheet0900aecd8033f885.html 1000BASE-BX10-D and 1000BASE-BX10-U SFP for Single-Fiber Bidirectional Applications The 1000BASE-BX-D and 1000BASE-BX-U SFPs, compatible with the IEEE 802.3ah 1000BASE-BX10-D and 1000BASE-BX10-U standards, operate on a single strand of standard SMF. A 1000BASE-BX10-D device is always connected to a 1000BASE-BX10-U device with a single strand of standard SMF with an operating transmission range up to 10 km. Figure 3.  Cisco 2-channel 1000BASE-BX optical SFP The communication over a single strand of fiber is achieved by separating the transmission wavelength of the two devices as depicted in Figure 3: 1000BASE-BX10-D transmits a 1490-nm channel and receives a 1310-nm signal, whe

如果各位正在上CCNA的課程或是在準備CCNA考試，但是平時可能手邊沒有設備可以練習的話，可以先考慮使用Packet Tracer來練習，以下是相關資源可以下載的地方： http://www.packettracernetwork.com/ Packet Tracer is a powerful network simulator that can be utilized in training for  CCNA TM  and CCNP TM  certification exam by allowing students to create networks with an almost unlimited number of devices and to experience troubleshooting without having to buy real Cisco TM routers or switches. The current version of Packet Tracer supports an array of simulated Application layer protocols (HTTP, DNS, …), as well as basic routing with RIP, OSPF, and EIGRP, to the extent required by the current CCNA TM  curriculum . With the introduction of version 5.3, several new features were added, including  BGP , which is part of the CCNP TM curriculum. While Packet Tracer aims to provide a realistic simulation of functional networks, the application itself utilizes only a small number of features found within the actual hardware running a current Cisco IO