Re: [PLUG] doubling bandwidth and achieving network redundancy

[Darxus@ChaosReigns.com]

On Tue, Aug 15, 2000 at 11:35:04PM -0400, Son To wrote:
> Suppose I get two ADSL line from two different ISP, can a Linux router
> be configured so that traffic is load balance between the two lines? A TCP
> data stream is sent/recieve using both lines. If one line goes down, my
> internal network should not notices the broken connection.

I found this question rather interesting, and whitnessed a conversation
about it.

My understanding is that there are 2 significant problems:

1) The dsl modems/routers are not capable of speaking BGP.
2) No one will listen to a route announcement to anything smaller than a
   /24, and no ISP is likely to give a DSL customer a /24.


The rest of this is my basic understanding of the above.  I reserve the
right to be wrong.


BGP (Border Gateway Protocol) is the protocol you need to speak to do
things like this.  A site with multiple internet connections gets a BGP
address that is independant of IP address space, which internet backbone 
routers use to figure out how to get stuff to it over the multiple lines.

My DSL provider gives me (assuming I did the math right), a /29.  I never
got around to figuring out the math of that definition of a subnet, but
I'm going to assume it means a 29 bit netmask =
11111111.11111111.11111111.11111000 = 255.255.255.248.  This means I get 8
addresses, the lowest of which is the network address, and the highest is
the broadcast address, and then another is assingned to my DSL modem.

A normal netmask (again, assuming I'm guessing correctly), is a /24 =
11111111.11111111.11111111.00000000 = 255.255.255.0.  Less bits.  So the
space needed to store the network address is shorter - only 3 bytes.  So
it would take another byte to store routes to a smaller subnet with a
larger mask.  1.33 times as much space.  


So maybe when IPv6 happens, if you could get a DSL router that could do
BGP, it'd be possible ?

-- 
www.ChaosReigns.com


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