[NEED HELP] forwarding multicast pakets

Hi,

I would like to simulate a WAN network on a LAN (with traffic control)
in order to test an application. That's why i've mounted a little
network with 3 PCs (2 tests PCs and a gateway in the middle) connected
'in line' like this :

1st test PC (WinXP) 192.168.1.2 (255.255.255.0)
||
eth0 192.168.1.1 (255.255.255.0) BROADCAST RUNNING MULTICAST
Linux gateway (Debian 2.6.8-2)
eth1 192.168.2.1 (255.255.255.0) BROADCAST RUNNING MULTICAST
||
2nd test PC (WinXP) 192.168.2.2 (255.255.255.0)

At the moment, I can ping and do FTP transfer between the two test-PCs,
but I can't use multicast applications.

My kernel config is :
CONFIG_IP_MULTICAST=y
CONFIG_NET_IPIP=m
CONFIG_IP_MROUTE=y
CONFIG_IP_PIMSM_V1=y
CONFIG_IP_PIMSM_V2=y
CONFIG_ADVANCED_ROUTER=y
CONFIG_MULTIPLE_TABLES=y
CONFIG_IP_ROUTE_FWMARK=y
CONFIG_IP_ROUTE_MULTIPATH=y

I'm using SMCRoute 0.92 with those commands :
# smcroute -d
# smcroute -a eth0 192.168.1.2 224.10.10.12 eth1
# smcroute -a eth1 192.168.2.2 224.10.10.12 eth0

If I look at the Mroute tables ( # ip route show ), I have got my two
routes :
(192.168.2.2, 224.10.10.12) Iif: eth1 Oif: eth0
(192.168.1.2, 224.10.10.12) Iif: eth0 Oif: eth1

But If I launch my multicast application for doing some test, I can see
with tcpdump that the incoming multicast traffic (224.10.10.12,
received either on eth0 or eth1) isn't forwarded on the other network
card.

Could you help me ?

Many thanks in advance.

up !

Hi,

On 2005-05-10, nouknouk <(E-Mail Removed)> wrote:
> Hi,
>
> [snipped]
>
> I'm using SMCRoute 0.92 with those commands :
> # smcroute -d
> # smcroute -a eth0 192.168.1.2 224.10.10.12 eth1
> # smcroute -a eth1 192.168.2.2 224.10.10.12 eth0
>
> If I look at the Mroute tables ( # ip route show ), I have got my two
> routes :
> (192.168.2.2, 224.10.10.12) Iif: eth1 Oif: eth0
> (192.168.1.2, 224.10.10.12) Iif: eth0 Oif: eth1
>
> But If I launch my multicast application for doing some test, I can see
> with tcpdump that the incoming multicast traffic (224.10.10.12,
> received either on eth0 or eth1) isn't forwarded on the other network
> card.
>
Exactly what I saw when cursing with my set. Whats the output from:

# ip mroute show

and also:

# cat /proc/net/ip_mr_vif

> Could you help me ?
>
adding 'up ip link set eth0 multicast off' to /etc/network/interfaces for the
interfaces where I did not want to see multicast traffic and also a good old:

# /etc/init.d/networking restart

helped no end, of course followed by your smcroute commands.

> Many thanks in advance.
>
have fun, streaming DVB data is good stuff.

Cheers

Alex

First, thanks for this answer.

This is what I get after :

# ifconfig eth0 up 192.168.1.1 netmask 255.255.255.0
# ifconfig eth1 up 192.168.2.1 netmask 255.255.255.0
# smcroute -d
# smcroute -a eth0 192.168.1.2 224.10.10.12 eth1
# smcroute -a eth1 192.168.2.2 224.10.10.12 eth0 (in order to add
multicast static routes)
#smcroute -j eth0 224.10.10.12
#smcroute -j eth1 224.10.10.12 (in order to join manually the multicast
group)
and after having launched (since a while) my two
multicast-test-applications on 192.168.1.2 and 192.168.2.2 (for
information they don't only send multicast packets, they do a multicast
group registering (IGMP) before )

#ip mroute show (it was what I writed in the last post. Sorry : it was
not 'ip route show' but 'ip mroute show')
(192.168.2.2, 224.10.10.12) Iif: eth1 Oif: eth0
(192.168.1.2, 224.10.10.12) Iif: eth0 Oif: eth1

# cat /proc/net/ip_mr_vif
interface Bytes In PktsIn BytesOut PktsOut
Flags Local Remote
0 eth0 0 0 0
0 00000 0100000A 00000000
1 eth1 170800 660 0 0
00000 0100000B 00000000

#tcpdump -i eth0
IP 192.168.1.2 > 224.0.0.22: igmpv3 report, 1 group record(s)
IP 192.168.1.2.8001 > 224.10.10.12.8001: UPD, length 234
IP 192.168.1.2.8001 > 224.10.10.12.8001: UPD, length 234
....
IP 192.168.1.2.8001 > 224.10.10.12.8001: UPD, length 234

#tcpdump -i eth1
IP 192.168.2.2 > 224.0.0.22: igmpv3 report, 1 group record(s)
IP 192.168.1.2.8001 > 224.10.10.12.8001: UPD, length 234
....
IP 192.168.1.2.8001 > 224.10.10.12.8001: UPD, length 234

I tried :
# ip link set eth0 multicast off
# ip link set eth1 multicast off
But nothing changes :-/

Moreover I don't understand why my interfaces should NOT have multicast
enabled ?
Could you explain me ?

Once again, many thanks in advance...

for this part :

#tcpdump -i eth1
IP 192.168.2.2 > 224.0.0.22: igmpv3 report, 1 group record(s)
IP 192.168.1.2.8001 > 224.10.10.12.8001: UPD, length 234
....
IP 192.168.1.2.8001 > 224.10.10.12.8001: UPD, length 234

sorry, but you should read :

#tcpdump -i eth1
IP 192.168.2.2 > 224.0.0.22: igmpv3 report, 1 group record(s)
IP 192.168.2.2.8001 > 224.10.10.12.8001: UPD, length 234
....
IP 192.168.2.2.8001 > 224.10.10.12.8001: UPD, length 234

(bad copy / paste in my post)

up!

On 2005-05-13, nouknouk <(E-Mail Removed)> wrote:
> First, thanks for this answer.
>
> This is what I get after :
>
> # ifconfig eth0 up 192.168.1.1 netmask 255.255.255.0
> # ifconfig eth1 up 192.168.2.1 netmask 255.255.255.0
> # smcroute -d
> # smcroute -a eth0 192.168.1.2 224.10.10.12 eth1
> # smcroute -a eth1 192.168.2.2 224.10.10.12 eth0 (in order to add
> multicast static routes)
> #smcroute -j eth0 224.10.10.12
> #smcroute -j eth1 224.10.10.12
>
this is _very_ wrong....I think Try instead:

# ifconfig eth0 up 192.168.1.1 netmask 255.255.255.0
# ifconfig eth1 up 192.168.2.1 netmask 255.255.255.0
# smcroute -d
# smcroute -a eth0 192.168.1.2 224.10.10.12 eth1
# smcroute -a eth1 192.168.2.2 224.10.10.<y> eth0

You cannot have *two* multicast sources on different networks with the same
IP, its like for regular non-multicast traffic. You need to make 192.168.2.2
broadcast to a different multicast address, say 224.10.20.12, instead.

With your rules you are doing the unicast equilivent of stating 192.168.1.2
exists _both_ off eth0 and eth1.

> Once again, many thanks in advance...
>
only here to help

Cheers

Alex

Well, I found the solution :
In fact, the soft I wanted to test had the TTL (Time to Live) variable
set to 1 (because for the tests before, we didnt want to flood the
entire network with our multicast packets).
As soon as I've set the TTL for the outgoing packets to 2 (or more),
the gateway with smcroute worked perfectly.

So, I'm sorry for having wasted some of your time :-/

Best regard.

Hi,

On 2005-05-23, nouknouk <(E-Mail Removed)> wrote:
> Well, I found the solution :
> In fact, the soft I wanted to test had the TTL (Time to Live) variable
> set to 1 (because for the tests before, we didnt want to flood the
> entire network with our multicast packets).
> As soon as I've set the TTL for the outgoing packets to 2 (or more),
> the gateway with smcroute worked perfectly.
>
> So, I'm sorry for having wasted some of your time :-/
>
don't be sorry, I would have missed that and more importantly so would have a
load of other people. You then posted back here you solution saving other
peoples time. Meanwhile Mr Alcatel[1] (I guess I could help him, but I'm
feeling like an Evil PFY today) decides to not reply....

Happy streaming

Alex

[1] subject lines 'SpeedTouch 330 gets disconnected too often' and
'SpeedTouch 330 modem firmware uploading problem :|' thought to leech the
knowledge from here.... :-/

> Best regard.
>