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Hi, sorry if I am asking a stupid question. I am building a router on a computer with 2 nics enp4s0(used as WAN) and enp6s0(used as LAN). The following is my dhcpcd.conf
noipv6rs
debuginterface enp4s0
ipv6rs
ia_na 1
ia_pd 2/::/56 enp6s0/1interface enp6s0
noipv4
Packet sniffing and manually ran dhcpcd confirmed that this is a working config: I had a /128 on WAN and a /64 on LAN, and with the help of radvd I could pass ipv6-test.com for my clients in LAN. But still I am really confused about this working config as I only figured it out through brutal force guessings. My questions are:
1. If I remove ia_na line, my LAN still received a /64, but WAN received nothing, if I change "ia_na 1" to "ia_na any other number", WAN would still receive nothing.
and
2. The only magical number I found which could make LAN receive successfully a /64 is to use "ia_pd 2/...." as in the config, if I change the number 2 into anything else, LAN would receive nothing.
I have tried reading the man page of dhcpcd.conf very hard but the more I read the more confused I became. Why this successful config has to have 1 and 2 for ia_na and ia_pd respectively....
I would appreciate it very much if anyone would kindly explain this to me. Thanks in advance!
Last edited by shallpion (2015-12-19 21:51:57)
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It could be that the upstream DHCP server has reserved IAID's 1 and 2 just for you.
IAID is a 4 byte opaque field that is just unique to each interface and address/prefix.
As you're sniffing the packets already, you should be able to confirm that only the IAID changes from working to non working when you change the values.
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Dear rsmarples, thank you so much for your suggestions and I indeed saw my ISP ignored my pd request unless I set its iaid as 2. I will mark this thread as solved. Thank you so much.
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