The fah client can upload completed WU's and download new WU's because the assigment servers do not have IPv6 addresses.
Code: Select all
; <<>> DiG 9.8.1-P1 <<>> aaaa assign3.stanford.edu
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28411
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;assign3.stanford.edu. IN AAAA
;; ANSWER SECTION:
assign3.stanford.edu. 1800 IN CNAME vsp10v-vz00.stanford.edu.
;; Query time: 91 msec
;; SERVER: 192.168.2.1#53(192.168.2.1)
;; WHEN: Thu Aug 9 16:02:49 2012
;; MSG SIZE rcvd: 64
The cores are only served on
http://www.stanford.edu which does resolve to an IPv6 address.
Code: Select all
; <<>> DiG 9.8.1-P1 <<>> aaaa www.stanford.edu
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17349
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;www.stanford.edu. IN AAAA
;; ANSWER SECTION:
www.stanford.edu. 300 IN CNAME www-v6.stanford.edu.
www-v6.stanford.edu. 1800 IN AAAA 2607:f6d0:0:925a::ab43:d7c8
;; Query time: 137 msec
;; SERVER: 192.168.2.1#53(192.168.2.1)
;; WHEN: Thu Aug 9 16:21:09 2012
;; MSG SIZE rcvd: 83
The current situation is that Stanford is telling the fahclient to use the IPv6 address (by way of DNS) to download the cores but the client does not know how.
The link above regarding setting Microsoft to prefer IPv4 to IPv6 is in response to a growing problems where sites and applications find themselves with IPv6 connectivity that they are not prepared for and rather than disable their own IPv6 connectivity they ask the whole world to do it instead.
In the long term the solution would be to fix the IPv6 issue in the fahclient
In the short term there are several options:
1) Ask everyone who has IPv6 connectivity (a number that keeps growing) to turn it off in the OS (not everyone will even know what IPv6 is let alone how to turn it off), thus severing their connection to any internet content that is not also available on IPv4 (an increasing number of sites).
2) Do not serve an IPv6 address for
http://www.stanford.edu. This may or may not be possible depending on the need for IPv6 connectivity for other services using
http://www.stanford.edu.
3) Use a different hostname for serving the cores and only serve an IPv4 address for this hostname. This would mean incorporating a change in the code (albeit a trivial one) but would also mean distributing the new code to all users.
