[Spread-users] Multi-homed multi-segment

[Jonathan Stanton]

Can you say more about why you are trying to use this configuration?

I can think of three scenarios for this (maybe there are others)

1) You want to use a "multi-path" fault-tolerance setup where spread 
runs rings on two separaet ethernet segments, and if one goes down 
(switch failure) Spread continues working by using the other network. 

In this case, Spread does not natively support that model. A number of
years ago a patch was written to add multi-path support to Spread
(against 3.16 and I heard it was ported to 3.17 versions). We
host a copy for download from our website, and link to it from the
development page. I don't see the link currently, but you can still get
the file at:

http://www.spread.org/files/multipath_3.16.1-5.tar.gz

This would definitely require some work to update it to the 4.0 code and 
clean it up for use, but at the time it was used by several groups for 
FT setups. I don't know if anyone on the list has current experience 
with it. 

2) You want to utilize the 2 separate ethernet interfaces to gain 
performance (i.e  messages/second ).

In this case it won't work. Spread assumes that each segment is a 
separate broadcast domain with unique machines on it. So every packet 
will be forwarded to all of the segments. So the result would be 
c1-master3 getting each packet twice, once on each interface.


3) You want to allow each spread daemon to listen on either interface 
for packets destined for it (whether client or daemon), but you don't 
need to replicate the sending of packets (as in case 1)

In this case Spread currently supports this. In this case you just have 
one Spread_Segment with all of the machines listed, For each one list 
both interfaces in the multi-home setup (like you have below)

If you do have some machines actually on a separate segment, you can 
list additional segments with those machines, but each physical machine 
(with 1 or more interfaces) is only listed once in the configuration.

This setup can work better with a multicast address instead of a 
broadcast address for the segment (replace 172.1.255.255 with 226.5.2.3 
-- or any valid multicast address)


If you had a different goal in mind, pleaes let us know and I can see 
whether it's possible with Spread or not.

Cheers,

Jonathan


On Tue, Sep 23, 2008 at 06:33:58PM +0100, Adrian Revill wrote:
> Yes you are right, im sorry i copied the wrong spread.conf
> 
> It should read
> Spread_Segment  172.1.255.255:4800
> {
> 
>        c1-master3      172.1.0.12 {
>                                172.1.0.12
>                                172.2.0.22
>                                127.0.0.1
>                                }
>       c1-quad-1       172.1.3.1
> }
> 
> Spread_Segment  172.2.255.255:4800
> {
>        c2-master23  172.2.0.22 {
>                             172.1.0.12
>                            127.0.0.1
>                            172.2.0.22
>                                }
>        c2-opto-2          172.2.2.2
> }
> 
> 
> 
> John Robinson wrote:
> >Adrian Revill wrote:
> >>Hi
> >>I have a server that has 2 NICs (172.1.x.x and 172.2.x.x) and i need 
> >>to run a daemon that can be a member of the two segments on each NIC
> >>
> >>I can only get master3 to appear as member of the 172.1.255.255 segment.
> >>
> >>Does anyone know how to be able to get master3 to be a member of both 
> >>segments?
> >>
> >>I have tried
> >>
> >>Spread_Segment  172.255.255.255:4800
> >
> >Shouldn't that be 172.1.255.255:4800 ?
> >
> >/jr
> >---
> >>{
> >>       c1-master3      172.1.0.12 {
> >>                               172.1.0.12
> >>                               172.2.0.22
> >>                               127.0.0.1
> >>                               }
> >>       c1-quad-1       172.1.3.1
> >>}
> >>
> >>Spread_Segment  172.2.255.255:4800
> >>{
> >>       c2-master3      172.2.0.22 {
> >>                               172.1.0.12
> >>                               127.0.0.1
> >>                               172.2.0.22
> >>                               }
> >>       c2-opto-2        172.2.2.2
> >>}
> >>
> >>
> >>
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-- 
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Jonathan Stanton         jonathan at spread.org
Spread Group Messaging   www.spread.org
Spread Concepts LLC      www.spreadconcepts.com
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