what is the solution ?

Unanswered Question
May 25th, 2008


I have central router where ISP1 is connected.

router WAN side ip=203.109.128.x/30

and LAN has real IP 203.109.127.x/28

so in my server (DNS, Mail,proxy) has real ip which given by ISP1.

my default route to ISP1

Now another ISP2 is connected in my central router , my aim is when ISP1 is down all traffic goes to ISP2.

ISP2 Ip is 112.123.12.X/30

For test purpose I am redirect route to ISP2. default route 0 0 ISP2.

My server IP segment is unchanged. now when I ping from my server to yahoo.com its ok. but when I am start browsing from my server, browsing is not ok. but that time when I am again defaut route move to ISP1 then browse is ok.

So its poroblem that LAN real IP another ISP and goes to different ISP ??

so I need to route 203.109.127.x/28 in ISP2 ???



I have this problem too.
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iqbalkhan Mon, 05/26/2008 - 02:15


I am agree with you that own subnet.

your another option is radware linkproof product which is a switch. the switch where connected ?,it is replace of my exsisting router ? if the router is serial connectivity then what happend ?.

besides this readware linkprrof product no other solution like This ip also introduce to ISP2 with permission of ISP1.



royalblues Mon, 05/26/2008 - 02:34

Radware is generally connected in between the router and the firewall or inside LAN in an one armed fashion i.e traffic enters and leaves thru the same port

The routing is modified in such a way that the default route which would generally point to the router is now pointed to the Radware and we have a /32 route for the FW interface pointing back to radware

When one ISP fails, the radware nats the packets again to the IP subnet of the 2nd ISP. This is called smart NAT by them. Your router can then be configured for PBR to route the ISP2 lan via the ISP2 link



iqbalkhan Mon, 05/26/2008 - 02:47


Thanks for understand. but need a little more.

in this case if i have real IP which assign by ISP1 then i do not need no change my Ip segment ?.In this case Radware is like only L-3 switch.

server--------Radware switch---router--ISp1

( Real IP-assign by ISP1) --Isp2

NB: If I have no product like this then what can I do ?




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