Dual ISP automatic failover

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Dec 16th, 2006
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Right now the technician setup our dual ISP connections as a manual cable switch. Does anyone know of a way to make the failover automatic and possible share the load? I know they have devices out there that will do it but we have all Cisco products. Also keep in mind that both have a different public IP blocks from different ISPs.

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kamal-learn Sat, 12/16/2006 - 08:54
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hi

is a good situation to use BGP, two different ISP!!! by using the BGP you will have the great opportunity to control your traffic, load balancing, and Backup !

if not use two defaults routes toward both ISP.


HTH

please do rate if it helps.

wrwiii122 Sat, 12/16/2006 - 09:03
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Well one of the ISPs does not use BGP. It is the local cable company(Time Warner). Can you set two default routes? The other problem is the traffic coming from the outside. We need to be able to let users access webmail and things like that from the public side.

sourabhagarwal Sat, 12/16/2006 - 10:10
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you can configure 2 default routes for auto failover like this.


ip route 0.0.0.0 0.0.0.0 s0/0

ip route 0.0.0.0 0.0.0.0 s0/1 100


route via s0/0 will be preferred over route via s0/1 because administrative distance of route via s0/1 is higher than s0/0.


I have assumed that s0/0 will be connected to ISP which you want to make primary path for traffic, in case s0/0 goes down, it will be removed from routing table and install route via s0/1 and traffic falls on the backup path.


Once s0/0 comes up, traffic will be shifted back to primary path.


hope to help .. rate if it does ...

wrwiii122 Sat, 12/16/2006 - 14:36
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Is this also cabable on a firewall or is this config on a router only?

kamal-learn Sat, 12/16/2006 - 17:13
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hi wrwiii122

try to post the schema of your network .

and elaborate more what you want to achieve!

we will try to help



Thanks

amit-singh Sat, 12/16/2006 - 21:00
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Hi,


I would never suggest to run default routes in the situation when you have 2 different ISP's feeding the internet to you.I would rather look for more controlled and filtered way for sending the traffic from 2 different ISP's.The idea behind this is that with default routes you dont know that traffic will hit which router and will use which link to go out forexample if you have a slow wan link and a high speed wan link, with default routes you dont have control over sending a majority of traffic thorugh high speed wan link and a little low traffic over the slow speed wan link.


If I were you, I would have thought of using NAT and PBR (policy based routing).I would first look at the kind of traffic, users, applications that I have to go the outisde world. Once the traffic is determined I would see the traffic distribution of the users over the two links. I would use my application, mail traffic to go thorough one link and internet and other traffic to use another link.I will make both the links as back up of each other.In case of one of the link goes my all the traffic will use the other link. I would suggest to implement proper QOS and rate limiting to drop the unwanted traffic.


NAT:


http://www.cisco.com/warp/public/556/12.html


Policy Based Routing:


http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/qos_c/qcpart1/qcpolicy.htm


www.cisco.com/warp/public/732/Tech/plicy_wp.htm


QOS:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cg/hqos_c/qchintro.htm


HTH,Please rate if it does.

-amit singh

wrwiii122 Mon, 12/18/2006 - 06:46
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So your telling me there is no easy way to have dual ISPs and have them automatically failover/load balance and recieve traffic from the outside world? There are so many devices out there that are cabable of doing this with a cheap little box and these high dollar cisco devices dont have a simple solution?


ISP1---2600Router--


PIXFirewall----LAN


ISP2---CableRouter--

Wrw, are you attempting to provide outbound and inbound failover and load-balancing? Do you want to balance per packet or per destination?


Inbound Failover (as if your hosting something interresting) is only capable using BGP-enabled ISP's, Inbound Load-Balancing is not possible if clients are configured with the same destination IP address, and certainly not if your ISP's don't do BGP.


Outbound Failover is possible using default routes and carefull tuning of cache entries to do what you want. Outbound Load-Balancing might also be possible if you realize the return path of your traffic will always flow based on your source address.


OR, just use one of these magic devices out there you speak of.


wrwiii122 Mon, 12/18/2006 - 11:47
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I am not as intrested in load balancing as much as I am for having an always up connection to the internet. I just want to make sure traffic flows in and out even if one ISP goes down.


For instance here is a product that does that : Xincom dual wan router

thanoskalogirou Sun, 01/21/2007 - 23:52
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Dear All,

In response to the subject discussed here i have a similar problem with a netkaffee. i have a cisco 2811 with 2 dynamic adsl loadbalanced. everything seems to work fine with cef and routemaps.(no accesslists)except the online games ex.(lineage) which disconnects very often from the game-servers.

what may the problem be? any advice why this happens?

olakunle06 Mon, 01/22/2007 - 04:07
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Can u kindly provide me solution and a write up for automatic failover.


i currently have a Netcom vsat internet access at 128/128kbps as our

primary link and a radio internet access from another isp as backup

whenever the vsat goes down

i would like;

1. the primary to failover to the backup when the primary is down

2. the failover to be seemless to users

3. to know, at administrator level, when the primary link goes down

during failover

4. the system to automatically switch back to the primary link when

the primary link becomes live again.

i anticipate ur swift response


olakunle06 Mon, 01/22/2007 - 04:43
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Can u kindly provide me solution and a write up for automatic failover.


i currently have a Netcom vsat internet access at 128/128kbps as our

primary link and a radio internet access from another isp as backup

whenever the vsat goes down

i would like;

1. the primary to failover to the backup when the primary is down

2. the failover to be seemless to users

3. to know, at administrator level, when the primary link goes down

during failover

4. the system to automatically switch back to the primary link when

the primary link becomes live again.

i anticipate ur swift response


Amit Singh Mon, 01/22/2007 - 04:54
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  • Cisco Employee,

Please see my post above. Which router you are using.Is it a single router or 2 routers.


-amit singh

autobot130 Mon, 12/18/2006 - 13:10
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The ideal setup where you probably would never have to touch or adjust again is to use BGP with the (2) ISPs and ASK just to receive "default route".


You can use any Cisco product ranging from 2600/2800/3600/3800. For BGP full routes where you can "tune" your traffic paths, you may need a router with at least 512MB of RAM.

wrwiii122 Fri, 12/22/2006 - 11:49
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The issue is that Comcast/Time Warner does not do BGP.

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