IPv6仍然用dynamic IP的問題

唔知大家覺唔覺有問題?

IPv4係LAN用private IP可以係唔同device都set一個static private IP,你記住個IP就可以,但用IPv6就變曬public IP,仲要係dynamic IP,想連入去時都唔知個IP係乜野,管理router也類似。

雖然IPv6都有private IP range(fc00::/7),openwrt也可以做到assign自己一個private IP,但其他device未必可以又dynamic又static IP,自動configure會出現一個好長的address(好似link-local address咁),唔知點記,唔似自己set IP咁方便可以只記頭64-bit同埋最後果個數字,中間全部要0(例如fc00::1、fc00::2、fc00::3等)。變左唔係要上HE自己攞一段/64或者/48就要用ip6tables照行NAT。

家用 internet ,香港大部份 ISP 定位為家居用途,假設你用黎上網,睇網站,或對外連線,所以用 dynamic IP 指派。

而你提及到的係連入 (被別人連線) 一般係伺服器用途,ISP 定義為非家用寬頻用途。。。

所以,其實在資源上,你根本就係會佔用一個固定 ipv4 和(或) ipv6 。。。但 ISP 也不會永久地指派比你 (當然,你長期唔 reboot router, 會好長一段時間使用同一個 IP )

所以,你個問題根本就係響 ISP 指唔指派固定 IP (包括 ipv6) 比你的問題。。。

當然,以前只記 wan 口一個 ipv4 就夠,其他 NAT port 位自己可 assign 。。。

你個問題套在固定 IP 上網計劃,便完全不存在。。。

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如果你係指後果段難記, 不如試下用dhcpv6派個易記IP, 不過可能舊少少OS既client就未必支援了。

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家用 internet ,香港大部份 ISP 定位為家居用途,假設你用黎上網,睇網站,或對外連線,所以用 dynamic IP ...
hkjimmytam 發表於 2015-12-1 06:07


似乎你唔係幾明我講乜。我係想講由電腦(192.168.1.100)連入去diskstation或其他設備(192.168.1.2)時用IPv4完全唔受外網影響。轉左IPv6之後頭64-bit受ISP影響,影響同一網絡內的裝置互連,要經常檢查IP頭64-bit是甚麼,影響體驗,仲有如果ISP down左,個prefix會冇左,但如果用static IP,仍然可以用set左入設備的IPv6係LAN連接。

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如果你係指後果段難記, 不如試下用dhcpv6派個易記IP, 不過可能舊少少OS既client就未必支援了。 ...
penthlon 發表於 2015-12-1 09:31


不過要檢查頭64-bit都係煩。

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本帖最後由 alanh999 於 2015-12-2 00:03 編輯

回覆 4# evantkh


    Under IPv6 protocol, each device will be assigned/self-generate more than one IP addresses and 2 of them are global IP and link-local IP.

Global IP addresses are from the prefix delegation which your ISP assigned to you. You could consider them as WAN IP and they are used for internet access.

Link-local IP addresses are self-generated by clients or assigned by DHCPv6 servers to identify the clients inside LAN. You could consider link-local IPs as LAN IPs and they are used for communications within LAN.

So lets put such setup into real-world situation.
Once your ISP changes the prefix delegation, you have to change the prefix of all global IP addresses held by your devices. Link-local IP addresses and LAN connections will not be interrupted.

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本帖最後由 evantkh 於 2015-12-2 00:11 編輯
回覆  evantkh


    Under IPv6 protocol, each device will be assigned/self-generate more than one I ...
alanh999 發表於 2015-12-1 23:53


Link-local IP is the IP generated by the client itself according to the MAC address, not assigned by the router, and it is too long to remember. One way is to use unique local address(fc00::/7) which you can assign freely, but the device usually does not allow two IPv6 addresses to be configured especially in two different modes(one in dynamic and the other static), another way is to assign local DNS names pointing to different link-local IP address which also increases the difficulty to setup for home users.

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本帖最後由 alanh999 於 2015-12-2 07:02 編輯

回覆 7# evantkh


    Link-local IP address could be self-generated or assigned by users. Thanks for correcting me on this.

ULA occupies the global IP address slot of a host. For a device with only one NIC (virtual NIC not included) you could either use ULA or global IP most of the time. You either assign ULA using DHCPv6 or do manual IP setup on the host.

You mentioned that IPv6 addresses are long......I think this is purely a habit thing which people are so used to how IPv4 works and they exhibit change-avoiding behavior towards IPv6.
You could create an excel file to document all essential link-local IPs, ULAs or global IPs which you have to remember, or just write them down on a paper.

Identifying hosts using host names is another preferred practice for IPv6, however this is too complicated to usual home users.

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回覆 4# evantkh

現在用 DHCPv6, 唔係用 IEEE 的 EUI64 標準咩?
EUI64 即用回MAC Address 48bit -> 64bit 做 Mapping.
前邊的  64bit ipv6 prefix 唔需要理會, 除非是外網 IPv6 進入
而且咁長的 IPv6 Address , 沒有人 會去記憶. 都是用回 DHCPv6 with DNS64 做 stateless DHCPv6 AutoConfig
到用時, 都只係記憶 DNS 或者 MAC Address 便可以, 根本上唔需要用 NAT64
ipv6 的 NAT64 都只係 做轉換 IPv6 Prefix. 或者 轉做 IPv4 用.

PS. IPv6 的 Address, 不是 給人去直接應用 或去 記憶的.

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本帖最後由 evantkh 於 2015-12-4 03:52 編輯
回覆  evantkh


    Link-local IP address could be self-generated or assigned by users. Thanks for  ...
alanh999 發表於 2015-12-2 06:53


Private DNS names is a good choice but home users may not understand, but I think some people who do not understand DNS may not understand how to assign static IPs to devices either.

My experience on using HE tunnel is obtaining a /48 and configure local devices like assigning IP with 2001:470:x::1,2001:470:x::2 etc. but it is transition only and also routes of Tier 1 ISP may not be as good as normal home -use ISPs due to peering locations and also partitoned network due to possible peering disputes.

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