[LARTC] default route

[LARTC] default route

[Payal Rathod]

Hi,
Is it possible to use more than one default route? I believe yes.
Any comments on them. If I use more than one, where will the trafficc be
diverted from?

With warm regards,
-Payal

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Re: [LARTC] default route

[Damion de Soto]

Payal Rathod wrote:
> Hi,
> Is it possible to use more than one default route? I believe yes.
> Any comments on them. If I use more than one, where will the trafficc be
> diverted from?
That's a good question.  I was going to answer your other post, but did some tests
which contradicted what I was going to say.

I originally thought if you had two default routes on the same metric, traffic would 
just go out the first one, however, when I tried this earlier, I started losing 
packets, so I can only assume the packets were going out the other route, and then 
getting lost. anyone comment on this ?

If you use the ip route tool to created multiple weighted or equalized default 
routes, you then use source-based routing to make sure that the traffic goes back out 
the same route it came in on.
(unless you're trying to be tricky with asymetrical routing)




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Re: [LARTC] default route

[Payal Rathod]

On Thu, Oct 30, 2003 at 04:29:25PM +1000, Damion de Soto wrote:
> >Is it possible to use more than one default route? I believe yes.
> >Any comments on them. If I use more than one, where will the trafficc be
> >diverted from?

> That's a good question.  I was going to answer your other post, but did 
> some tests
> which contradicted what I was going to say.
> 
> I originally thought if you had two default routes on the same metric, 
> traffic would just go out the first one, however, when I tried this 
> earlier, I started losing packets, so I can only assume the packets were 
> going out the other route, and then getting lost. anyone comment on this ?


A friend of mine says that if y ou have 2 default routes on different
subnets each the routing will be done randomly. Unfortunately I do not
have that kind of setup to test.
I did it on same subnet using 2 default routes and found that I was
losing packets too.


> If you use the ip route tool to created multiple weighted or equalized 
> default routes, you then use source-based routing to make sure that the 
> traffic goes back out the same route it came in on.
> (unless you're trying to be tricky with asymetrical routing)

Isn't random routing (without depending on source) easy to implement
than source based routing?
Can you please tell what you mean by using ip route to create multiple
weighted routes? I have absoluttely no idea what ip command does
exactly. I am using just plain "route" and ifconfig. Are they
decrepated?

With warm regards,
-Payal

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Re: [LARTC] default route

[Vadiraj C S]

On Thu, 29 Oct 2003, Payal Rathod wrote:

> Hi,
> Is it possible to use more than one default route? I believe yes.
> Any comments on them. If I use more than one, where will the trafficc be
> diverted from?

 Yes you can, the traffic gets balanced between two routes...


Vadiraj C S

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Re: [LARTC] default route

[Vadiraj C S]

On Thu, 30 Oct 2003, Damion de Soto wrote:

> getting lost. anyone comment on this ?
>
> If you use the ip route tool to created multiple weighted or equalized default
> routes, you then use source-based routing to make sure that the traffic goes back out
> the same route it came in on.
> (unless you're trying to be tricky with asymetrical routing)

  I tried this, the routes get cached so most of the time the packets
  leave from the route they came in, but you can have two routes and
  there is no packet loss.

Vadiraj C S

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Re: [LARTC] default route

[Vadiraj C S]

On Thu, 30 Oct 2003, Payal Rathod wrote:
> Can you please tell what you mean by using ip route to create multiple
> weighted routes? I have absoluttely no idea what ip command does
> exactly. I am using just plain "route" and ifconfig. Are they
> decrepated?

  ip is more flexible, ip can do both the jobs i.e what route and ifconfig does.  Download iproute2  package and you can know it by your self.

Vadiraj C S

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Re: [LARTC] default route

[Payal Rathod]

On Thu, Oct 30, 2003 at 01:18:23PM +0530, Vadiraj C S wrote:
> > Is it possible to use more than one default route? I believe yes.
> > Any comments on them. If I use more than one, where will the trafficc be
> > diverted from?
> 
>  Yes you can, the traffic gets balanced between two routes...

Ok. Just an sacrileige question. Are you 100% sure?
Can you say with surety that with 2 default gateways, packets won't get
lost any time.
Thanks for the comments.
Regards,
-Payal
p.s. deeproot rocks :)


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Re: [LARTC] default route

[N N Ashok]

On Thursday 30 October 2003 02:52 am, Vadiraj C S scrawled:
> On Thu, 30 Oct 2003, Damion de Soto wrote:
> > getting lost. anyone comment on this ?
> >
> > If you use the ip route tool to created multiple weighted or equalized
> > default routes, you then use source-based routing to make sure that the
> > traffic goes back out the same route it came in on.
> > (unless you're trying to be tricky with asymetrical routing)
>
>   I tried this, the routes get cached so most of the time the packets
>   leave from the route they came in, but you can have two routes and
>   there is no packet loss.
>
> Vadiraj C S
>

hi,
Having multiple equal cost routes just ensures that the traffic is balanced 
per-route, i.e.  every time a route is looked up in the FIB table, the 
load-balancing comes into picture. but once a route has been established for 
a destination, it is cached and all packets to that destination go via that 
route. However, if you install the nano patch 
(http://www.ssi.bg/~ja/nano.txt), the the load-balancing is done on a 
per-packet basis. so for every packet, leaving the system (either forwarded 
or output), the FIB table is consulted and the packets are balanced on the 
multiple equal-cost paths provided you have 'equalize' keyword for that 
multiple equal-cost route.

current i am actually implementing load-balancing (outgoing) on a per-session 
and current-bandwidth-usage basis.

hope that helps.
ashok

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