On Jun 30, 1:58 pm, Trendkill <jpma...@gmail.com> wrote:
> On Jun 30, 2:48 pm, TheGoD <tgupt...@gmail.com> wrote:
>
> > Hi Techies....
>
> > I'm stuck in a problem....as i'm not very well with cisco routers...
>
> > I have a cisco router 1800 series with a 4 port fast ethernet card.
> > now i have attached both the internet isp's (A and B) over ethernet to
> > this router, now what i need is that all my traffic for internet from
> > lan A (192.168.1.0/24) should be routed to isp A and all from lan B
> > (10.220.16.0/24)should be routed to isp B.
>
> > Please ckick the link for the diagram.http://img248.imageshack.us/my.php?i...rawing1jq5.jpg
>
> > Thanks..............
>
> Policy-based routing is your only option. Else all traffic will take
> one path, the other, or both (depending on your configuration), but
> will not be split based on source network. Search policy-based
> routing or PBR on cisco, lots of good documentation.
This only solves one part of the routing equation in that traffic out
to the Internet will indeed leave the connection specified, however it
does not influence the way the traffic will return to your network
which is normally more important (load balancing inbound flows which
are much larger normally than the outbound flows). That cannot be
solved by the end customer without using some very creative routing
and even then you are at the mercy of your provider to make it work.
Normally you would use BGP for that and you would split your IP
address pools in half or more and advertise one half to one provider,
and the other half to the other. At the same time you would advertise
a summary of the entire pool to both providers for failover purposes.
This is a very complex problem in large networks which have large
amounts of IP space that they can use to load balance. Even then, you
have to look at what servers reside in that IP segment (or pool) and
determine if you are truly load balancing (ie if your largest servers
all sit in the same /24 and you are advertising /24 networks to your
upstream provider then most of your traffic will still only use one
link). If both links are to the same ISP router then you can use BGP
MED (communities) to influence it but again provider dependent.