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Old 12-01-2006, 04:18 PM   #1
LQ Newbie
Registered: Apr 2006
Posts: 27

Rep: Reputation: 15
multi-home on two ISP networks


Trying a test config where I have DSL and Cable both feeding into my server. The server runs Apache web server. The problem seems to be the Linux routing tables all point to rather than the real network for them. I tried "route add" and have started to look at iproute2. The iproute2 page mentions a problem which may be it... if Linux is transmitting over a network 1 (the cable network say) but the request came through network 2 (the dsl network) then the cable network will drop it.
Basically, looking for advice on multihoming on a home/SBA network for fault tolerance. My TWX cable modem hangs about once every two weeks. I read about setting up OSPF and BGP but this is simply a home network.
Here's what works. Apache is set to "Listen 80" meaning it listed on both NICs. Requests from either LAN are served. Good. Requests from the big net to the first LAN are served. Good. Requests from the big net to the second LAN are not served.
I can disable NIC1 and then requests from the LAN to the second NIC work, so I know that network is setup to work.
Here is some more detail:
1. DSL network.
2. Cable network:
Hosts /etc/hosts: localhost.localdomain localhost
Apache config: /etc/httpd/conf/httpd.conf
Listen 80
#Listen # Thought I could toggle the NIC with this but
fails to respond.
#ServerName # Argh! Virtual Hosts fails with this -
maybe due to /etc/hosts?
Route route -n:
Destination Gateway Genmask Flags Metric Ref Use
Iface U 0 0 0 eth0 U 0 0 0 eth1 U 0 0 0 eth1 UG 0 0 0 eth1
# This route does not look right to me. I thought I'd see something like:
> Destination Gateway Genmask Flags Metric Ref
Use Iface
> U 0
0 0 eth0
> U 0
0 0 eth1
# Does not that make more sense? I tried setting these in
system-config-network but does not seem to take as the changes do not
show in route -n.

TimJowers : Serviza Monster Linux Computers and Training.
Old 12-02-2006, 10:28 AM   #2
Registered: Sep 2005
Location: New delhi
Distribution: RHEL 3.0/4.0
Posts: 777

Rep: Reputation: 31 must be having a single real public ip & that we can get via nslookup or ping. But when you have two different ISP, how can you have your single real-public IP mapped at both interfaces, NO. So only one of your cable/dsl would be having your real public internet ip & that only would be forwarding it to your box.

So further from here what is your problem now ???


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