[Spread-users] Retransmission and Connection Problems

[Jeremy McDermond]

On Thursday, October 2, 2003, at 03:46 PM, Yair Amir wrote:

> Hi Jeremy,
>
> It seems that your broadcast address does not work correctly on all of
> the machines. This is why I am sure it works with any two machines and
> will not work for you with three or more machines.
>

I've looked to make sure the switch doesn't do any broadcast 
limitations, and I've checked each of the three machines to make sure 
the broadcast address is set correctly on the appropriate ethernet 
interface.  FreeBSD should not be doing broadcast limiting either.  
Interestingly when I change the ring address to 225.0.1.1 for 
multicast, none of it seems to get through at all.  I've sniffed the 
wire from one of them, and there's no IGMP requests sent out the 
interface to join multicast groups.  If I use the mtest utility, I see 
the IGMP traffic getting sent to start up group traffic.  These 
machines are also multi-homed.  There are 3 ethernet interfaces on each 
one, and the 10.1.0.0/16 network is the one that should be handling the 
spread traffic.  Is this something that I need to use the D/C syntax to 
make multicast work correctly?  It should know the interface to enable 
by the address already on the config line, right?

a.www.peak.org [ /usr/local/etc ] # ifconfig bge0
bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
         options=1b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING>
         inet 10.1.4.1 netmask 0xffff0000 broadcast 10.1.255.255
         inet6 fe80::206:5bff:feef:713c%bge0 prefixlen 64 scopeid 0x1
         ether 00:06:5b:ef:71:3c
         media: Ethernet autoselect (100baseTX <full-duplex>)
         status: active

b.www.peak.org [ ~/spread-src-3.17.1 ] # ifconfig bge0
bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
         options=1b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING>
         inet 10.1.4.2 netmask 0xffff0000 broadcast 10.1.255.255
         inet6 fe80::206:5bff:feef:7168%bge0 prefixlen 64 scopeid 0x1
         ether 00:06:5b:ef:71:68
         media: Ethernet autoselect (100baseTX <full-duplex>)
         status: active

a.monitor.peak.org [ /usr/local/etc ] # ifconfig vlan20
vlan20: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1496
         inet 10.1.255.253 netmask 0xffff0000 broadcast 10.1.255.255
         ether 00:06:5b:ec:5c:95
         media: Ethernet autoselect (100baseTX <full-duplex>)
         status: active
         vlan: 20 parent interface: em0

Our switch could be flakey -- but I'm seeing no errors on the ethernet 
interfaces themselves.

> You could use a multicast address instead of the 10.1.255.255 (which
> does not work for you) - such as 225.10.1.4. That would probably
> work for you. Otherwise, make sure all of the machines are set
> correctly with the broadcast address.
>

Like I say, with multicast it seems like it reverts completely to 
unicast to try to make the ring work.

> There were several similar cases that were discussed on the mailing
> list in the past.
>
>      :) Yair.

Thanks so much for your reply Yair -- I really appreciate the 
assistance.

--
Jeremy C. McDermond                                                     
   mcdermj at peak.org
Lead Engineer
Peak Internet, LLC                                                      
                 (541) 738-4921