Fwd: [CentOS] Fwd: How to add a route to a network via 2 gateways.

Sun Dec 31 00:06:38 UTC 2006
Peter Farrow <peter at farrows.org>

Hi There,

the bigger the weight relative to the other gateway the more likely it 
is chosen a weight of 1 and 100 will mean the 100 choice is 100x more 
likely in theory.

If either gateway is down the other is routed automatically,

I have two 8 meg SDSL lines at home and balance them in this way....


P.


Indunil Jayasooriya wrote:
> HI Peter,
>
> Interesting in deed. You say that  You can add a second route and 
> weight it as follows:
>
> ip route add equalize *MailScanner warning: numerical links are often 
> malicious:* 192.168.2.0/24 <http://192.168.2.0/24> scope global 
> nexthop via
> *MailScanner warning: numerical links are often malicious:* 
> 192.168.0.254 <http://192.168.0.254/> dev eth0 weight 1 nexthop via 
> *MailScanner warning: numerical links are often malicious:* 
> 192.168.0.250 <http://192.168.0.250/> dev eth0 weight 1
>
> I want to know whether I can use the above command , when the below 
> command exists .
>
> ip route add *MailScanner warning: numerical links are often 
> malicious:* 192.168.2.0/24 <http://192.168.2.0/24> via *MailScanner 
> warning: numerical links are often malicious:* 192.168.0.254 
> <http://192.168.0.254/>
>
> Then I want to know about your second answer which is "To achieve the 
> goal of primary path only, you can heavily weight one path over the 
> other, some traffic will still spill into the other, you
> can remove the equalize parameter to disable this behaviour "
>
> herein,  what is this "you can heavily weight one path over the other"
>
> When weight 1 and weight 1 , Both paths are equal. If I use weight 1 
> and weight 100 , what would be the primary path ? Is it weight 1 ?
>
> Is it the lower number which becomes primary ?
>
> Then , in my case, is the following coomad is right?
>
> ip route add  *MailScanner warning: numerical links are often 
> malicious:* 192.168.2.0/24 <http://192.168.2.0/24> scope global 
> nexthop via
> *MailScanner warning: numerical links are often malicious:* 
> 192.168.0.254 <http://192.168.0.254/> dev eth0 weight 1 nexthop via 
> *MailScanner warning: numerical links are often malicious:* 
> 192.168.0.250 <http://192.168.0.250/> dev eth0 weight 100
>
> I guess with the above command that traffc will flow via primary, when 
> it fails , traffic will flow via secondary.
>
> That is what I need.
>
>  Am I right ? Then can I acheive this goal ?
>
> Thanks
> Indunil
>
> ---------- Forwarded message ----------
> From: *Aleksandar Milivojevic* <alex at milivojevic.org 
> <mailto:alex at milivojevic.org>>
> Date: Dec 30, 2006 3:37 AM
> Subject: Re: [CentOS] Fwd: How to add a route to a network via 2 gateways.
> To: centos at centos.org <mailto:centos at centos.org>
>
> Quoting Indunil Jayasooriya < indunil75 at gmail.com 
> <mailto:indunil75 at gmail.com>>:
>
> > Hi ,
> >
> > I have a network to reach which is *MailScanner warning: numerical 
> links are often malicious:* 192.168.2.0/24 <http://192.168.2.0/24>. It 
> is a branch of the
> > company. I have currently added a route to that network via one 
> gateway (
> > *MailScanner warning: numerical links are often malicious:* 
> 192.168.0.254 <http://192.168.0.254>) in following way.
> >
> > ip route add *MailScanner warning: numerical links are often 
> malicious:* 192.168.2.0/24 <http://192.168.2.0/24> via *MailScanner 
> warning: numerical links are often malicious:* 192.168.0.254 
> <http://192.168.0.254>
> >
> > Now, We got another gateway which is *MailScanner warning: numerical 
> links are often malicious:* 192.168.0.250 <http://192.168.0.250>. Now 
> I want to add a
> > route to the same network  which is *MailScanner warning: numerical 
> links are often malicious:* 192.168.2.0/24 <http://192.168.2.0/24> via 
> this gateway
> > (*MailScanner warning: numerical links are often malicious:* 
> 192.168.0.250 <http://192.168.0.250>)
> > as well.
> >
> > Then I will have 2 paths to the same network. One path should be 
> primary and
> > the other path  should be backup. everything should go via primary 
> path.
> >
> > if the primary  path goes down, the backup path should be active.
> >
> > That is the purpose of doing this.
> >
> > Pls let me know whether it is possible or not?
> >
> > if possible, How can I achieve this goal.
>
> One possible solution is to enable one of the routing protocols on
> your routers, instead of using static routing.  For example BGP or
> OSPF.  The routers will than discover which paths to every of the
> networks you have exist and will dynamically change routing rules
> (instead of using static set of rules) as the network connections go
> up and down.  In the way you requested in your question.  It might be
> an overkill for simple network.  But if your network becomes more
> complex in the future, you'll have infrastructure to handle it.
> Another advantage of using standard routing protocol is that they tend
> to be platform independent.  You want to replace that Cisco router
> with Linux router or Linux router with Cisco router.  Guess what, you
> can use BGP or OSPF on both Linux and Cisco based router and your
> configuration is not specific to single type of router anymore.
>
>
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>
>
> -- 
> Thank you
> Indunil Jayasooriya
>
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