routing by service
Currently i have two small groups of computers, one formed by three
computer plus guests (portables), connected to an ADSL router that has a
static address of a.b.c.d and does natting, and is set to use dmz for
one of the computers, and assigning two ports to each of the local
computers for inbound service
these computer locally use addresses 192.168.2.17
and up to 30 with a /24 subnetting ( 192.168.2.1 is the router )
the second group is formed by one computer plus guests and is connected
via a bridge to the first one, and uses addresses from .49 upward.
All works fine except that sometimes bandwidth available for the second
group is insufficient (either since the internet band is saturated or is
just saturated the link between the two subgroups).
I decided to get a second ADSL link, with the same speed of the first one,
but with a dynamic address, from a different ISP (to reduce possible
problems), with a similar setup giving .33 to it)
Now i wish the following:
The first group continue to use the present ISP;
the second one should use the second ISP except in the following cases:
1. is connecting to certain hosts [list A] using certain ports on the
remote host
(typycally 25 80 443 631 that have applications that depend on the address
on the other side)
2. is connecting to certain hosts [list B] whitout respect of the port
used
3. bandwidth used on the second link from other application/computers is
above a certain threshold (to avoid slow response)
Of course in case of a break on each of the links both groups should use
the working one, and if one try to connect one of the computer in the
other subnet should use the "direct" link.
I thought of setting the two routers so they assing the correct gateway to
each computer, and this works fine (the bridge between slow the
connections enought so the address is always given by the dhcp server on
the "correct" side.
for case 2 of course is sufficent setting a static route.
how to do for case 1 and 3 ?
how to set routing (if possible by dhcp) to use a route for certain remote
ports and another for the others ?
how to start two ftp connections possibly to the same host, but asking to
use one route for one and another for the other ?
(it would be easy if the remote host would be multi homed, but how to do
if has a single address ? it is not a router problem this one but rather
an application issue, since the connection would go to two differnte
routers)
??
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