On 3/16/21 12:27 PM, Kasemir, Kay via Core-talk wrote:
>> Personally, I see IPv6 as one of several "modernization" requirements
>
> In principle, the PVAccess protocol is prepared for IPv6.
> For example, search replies have room for v6 addresses.
> When I worked on the updated Java lib, I found a few places in the original Java code which comments like "current use of multicast addresses works only with INET, not INET6".
> So the channel for the UDP port is opened for INET, not INET6 protocol.
> But I've never tried it with INET6, no idea what the specific issues would be.
> Does anybody know?
I looked into this when I started on PVXS. Conceptually there is no
problem. However, I ultimately encountered enough implementation issues
that I didn't go though with it. Those I recall are:
1. Adding sockaddr_in6 to osiSockAddr breaks basically all existing code on *BSD (including OSX)
On targets with BSD derivative network stacks, syscalls like bind() which take
'size_t socklen' error unless the size exactly matches the address family.
eg. AF_INET expects socklen==sizeof(sockaddr_in). Linux is more permissive
and allows socklen to be larger. I didn't get as far as testing windows.
2. Network interface inspection doesn't include IPv6 addresses
3. IPv6 doesn't have broadcasts
Use of unicast or multicast becomes mandatory.
I think this would mainly effects configuration.
4. Target support. (RTEMS legacy network stack is a non-starter)
5. How to handle interop in a mixed IPV4/6 installation?
> Would an effort to support IPv6 consider updating Channel Access, or would we concentrate on PVAccess?
Personally, I think it would be better to focus on PVA where there are
(I think) only implementation issues. Also fewer implementations.
It should be possible to extend the design of CA to include IPv6.
eg. it might be as simple as disallowing "name server" search
replies over IPv6. This is the only case where an IPv4 address is
encoded in a message. If this isn't sufficient, then at least
a limited redesign would be needed.
- References:
- IPv6 Johnson, Andrew N. via Core-talk
- Re: IPv6 Zimoch Dirk (PSI) via Core-talk
- Re: IPv6 Ben Franksen via Core-talk
- Re: IPv6 Johnson, Andrew N. via Core-talk
- Re: IPv6 Michael Davidsaver via Core-talk
- Re: [EXTERNAL] Re: IPv6 Kasemir, Kay via Core-talk
- Navigate by Date:
- Prev:
RE: IPv6 Mark Rivers via Core-talk
- Next:
Re: IPv6 Jeong Han Lee via Core-talk
- Index:
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
<2021>
2022
2023
2024
- Navigate by Thread:
- Prev:
Re: [EXTERNAL] Re: IPv6 Kasemir, Kay via Core-talk
- Next:
RE: IPv6 Mark Rivers via Core-talk
- Index:
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
<2021>
2022
2023
2024
|