| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 98 === DVR (Digital Video Recorder) is one of the major products in surveillance
industry. In addition to using hard disk as storage media, the major
difference between DVR and conventional recording system is the
application of network protocol. It also provides the possibility of remote
monitoring.
No matter how many network protocols have been used in DVR products,
it is for sure that some problems will occur during development. This
thesis mentions a serious problem DVR could meet if it integrates DDNS
function. When DVR is located in a LAN environment and rely on a router
to communicate with Internet, DVR may have no way to get router’s
external IP address. Since DVR needs to know the correct external IP
address to determine when it needs to send DDNS update packet, it may
not be able to send DDNS update packet at correct time if DVR does not
notice the change of router’s external IP address. This could generate
inconsistency issue between IP address and the domain name that user
retrieved from DDNS provider. If DVR could detect the change of router's
external IP, and send DDNS update packet to DDNS server at correct
timing, then this self-adaptive function can keep consistency between
domain name and external IP address.
In addition to discussing the problem with DDNS update mechanism with
DVR, the thesis also provides two possible methods to solve this issue,
and compares the advantage/disadvantage with both ways. DVR related
products are also introduced in this thesis, with brief discussion for
compress technology and network protocols that DVR related products
will use. Some of the real cases when developing DVR products with
network protocols are also mentioned and described.
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