Multicast address on CE 5.0

[Alistair]

Hi

I have a bare test app for getting multicast up and running, and when
compiled on the desktop for XP, it works fine: the socket creates ok, the
soket is bound to the correct address and a read thread is launched
containing a recvfrom(), socket options are set to join the multicast group
on the appropriate port, and i can send and receive data just fine.

however when compiled on CE 5.0 for our target, all the calls perform
successfully, including setsockopt() with IP_ADD_MEMBERSHIP, yet the CE app
never receives any multicast data (while running XP peers do) but can send
just fine.

I have contacted the BSP vendors tech support but while I await thier
response, I saw this posted by Paul G. Tobey on 12th June 06 in the thread:
setsockopt(IP_MULTICAST_TTL,...) fails, why?

]"There's also a bug in multi-cast group membership that you should probably
]check the archives for. Another user found it and I confirmed it. Related
]to the value in b and c of a.b.c.d where that's the group address you're
]trying to join. I think that both b and c had to be zero, or something
like
]that. That shouldn't affect your TTL problem, but it will affect whether
]you actually get any packets, once you've got TTL working."

If this is the case I think I have fallen foul of this bug, but am unable to
find any more information on this.
I have searched the groups through google with 'multicast' 'multicast
windows ce' 'multicast bug' 'multicast windows ce bug' 'multicast ce
receive bug' yet yet can't find the appropriate (or similar) thread.

If someone could point me in the right direction I'd be most greatful.

Cheers!
--
Alistair Brugsch
Software Engineer - Honeywell HPS
Please ask to email

[Paul G. Tobey [eMVP]]

Yes, it's a bug. If your IP address for the group doesn't meet the
requirements to work around the bug, you won't get any messages. Don't use
such a group number and it will work fine.

Paul T.

"Alistair @honeywell.com>" <ringwood<do_not_email_this_address> wrote in
message news:%23Wv2em8...@TK2MSFTNGP03.phx.gbl...

[Alistair]

Thanks, so is this documented anywhere? perhaps a KB article?
The product hasn't started going out the door yet so the address hasn't been
set in stone. where can I find what addresses work or is it a case of trial
and error?

many thanks!
Alistair

--
Alistair Brugsch
Software Engineer - Honeywell HPS
Please ask to email

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:eMGkGo9t...@TK2MSFTNGP02.phx.gbl...

[Alistair]

I found the actual thread with the solution: (however it hasn't worked)
Multicast and winCE started by shantanu_kush on Jan 25th

"Paul G. Tobey [eMVP]" wrote:
>It appears to me that any group address which does not have 0's in the b
>and c positions of a.b.c.d will not work. Further, any address, even if b
>and c are zero, where d has bit 0 or 1 set doesn't seem to work, either.
>So a.0.0.4 works, but a.0.0.5 does not and neither does a.0.0.6. Strange
>bug...

also in there was a pointer to this MSDN article
http://www.google.com/url?sa=D&q=http://msdn.microsoft.com/library/default.asp%3Furl%3D/library/en-us/wcetcpip/html/cmconparametersconfigurableusingregistryeditor.asp
so I too have set HKEY_LOCAL_MACHINE\Comm\Tcpip\Parms\IGMPLevel to 2

the remainder of my situation appears to be the same as Shantu's except that
his ultimate solution hasn't worked for me.
I'm stillwaiting for a response from my BSP vendor, so maybe they'll have an
answer.
Alistair

--
Alistair Brugsch
Software Engineer - Honeywell HPS
Please ask to email

"Alistair @honeywell.com>" <ringwood<do_not_email_this_address> wrote in
message news:OxnxhNfu...@TK2MSFTNGP03.phx.gbl...

[Paul G. Tobey [eMVP]]

So, you're setting that same group address and it doesn't work for you?
Checked the firewall settings?

Paul T.

"Alistair @honeywell.com>" <ringwood<do_not_email_this_address> wrote in

message news:eOjud7fu...@TK2MSFTNGP03.phx.gbl...

[Alistair]

Yes, I've used these addresses, plus many others, and in each case, the CE
client can send to the group and be picked up, by XP clients, but not vice
versa.

there is no software firewall on the CE or XP hosts, and there will be a
firewall on the gateway, however that should have no effect on our segment.
and at any rate, the XP hosts have no trouble communicating, just the CE
hosts are deaf.

I've had a response from our BSP vendor:
>.......I assume multicast/broadcast was working because this is how DHCP
>works.
>The Ethernet driver has the multicast functions filled and you describe it
>working through the loopback, so that confirms the >driver functionality is
>present.

>Have you looked at the Platform Builder 5.0 help which should explain and
document this functionality well?

>If not this would be a recommended starting point.

I haven't looked at PB docs yet, but as this is not generally my domain, I
haven't a clue where to start. I will talk to the guy that does that now
he's back.

--
Alistair Brugsch
Software Engineer - Honeywell HPS
Please ask to email

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT

com> wrote in message news:ehR2Hpju...@TK2MSFTNGP03.phx.gbl...

[Alistair]

apologies if this is a double post --- i'm not sure my news reader sent it
in the first place, and it hasn't shown up 3 hrs after posting. if this and
it's original both appear, please accept my apologies.

Msg follows:

Yes, I've used these addresses, plus many others, and in each case, the CE
client can send to the group and be picked up, by XP clients, but not vice
versa.

there is no software firewall on the CE or XP hosts, and there will be a
firewall on the gateway, however that should have no effect on our segment.
and at any rate, the XP hosts have no trouble communicating, just the CE
hosts are deaf.

I've had a response from our BSP vendor:
>.......I assume multicast/broadcast was working because this is how DHCP
>works.
>The Ethernet driver has the multicast functions filled and you describe it
>working through the loopback, so that confirms the >driver functionality is
>present.

>Have you looked at the Platform Builder 5.0 help which should explain and
document this functionality well?

>If not this would be a recommended starting point.

I haven't looked at PB docs yet, but as this is not generally my domain, I
haven't a clue where to start. I will talk to the guy that does that now
he's back.

--
Alistair Brugsch
Software Engineer - Honeywell HPS
Please ask to email

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT

com> wrote in message news:ehR2Hpju...@TK2MSFTNGP03.phx.gbl...

[caoqua...@gmail.com]

Hello,

I have a similar problem for udp reception,

I found your post and i wonder if you got a solution for that,

Please help me,

Best regards,

Hung,