[TriLUG] Routing...once again.

[Ryan Leathers]

oops - on second read I realize what Rick was really asking...
yep Aaron gave the wrong address.  The match should have been 2.2.2.0/24
out eth1 not 1.1.1.0/24 out eth0

my apologies for wasting time with the previous post


On Thu, 2006-08-10 at 12:33 -0400, Ryan Leathers wrote:
> Rick,
> 
> the .10, being a host in the 2.2.2.0/24 network, would not be matched by
> the routing process, but the 2.2.2 portion of the address would be.  The
> packet would be routed out the corresponding interface, and if directly
> connected, the layer 2 address of the destination would be retrieved
> from cache or ARP.
> 
> So, the netstat entry of 2.2.2.0 is showing you the portion of the
> address that routing decisions will be based on.  The 2.2.2.10 address
> offered in Aaron's example is a valid address in the 2.2.2.0/24 network
> which will result in a layer 3 forwarding decision by the Linux host.
> 
> Make sense?
>   
> 
> On Thu, 2006-08-10 at 11:44 -0400, Rick DeNatale wrote:
> > On 8/9/06, Aaron S. Joyner <aaron at joyner.ws> wrote:
> > 
> > > asjoyner at bob:~$ netstat -rn
> > > Kernel IP routing table
> > > Destination     Gateway         Genmask         Flags   MSS Window  irtt
> > > Iface
> > > 1.1.1.0         0.0.0.0         255.255.255.0   U         0 0          0
> > > eth0
> > > 2.2.2.0         0.0.0.0         255.255.255.0   U         0 0          0
> > > eth1
> > > 0.0.0.0         1.1.1.254       0.0.0.0         UG        0 0          0
> > > eth0
> > >
> > > When you address a packet to 2.2.2.10, that Linux box will look at your
> > > routing table, and choose the network with the best match for that
> > > packet, which is 1.1.1.0 with a mask of 255.255.255.0.
> > 
> > Teacher, teacher?
> > 
> > Did you really mean "which is 2.2.2.0 with a mask of 255.255.255.0"?
> > Or am I missing something subtle?
> > 
> > I know less than enough about network routing to be dangerous.
> > 
> > -- 
> > Rick DeNatale
> > 
> > IPMS/USA Region 12 Coordinator
> > http://ipmsr12.denhaven2.com/
> > 
> > Visit the Project Mercury Wiki Site
> > http://www.mercuryspacecraft.com/
>