router availability

[Scot L. Harris]

On Tue, 2005-02-15 at 15:29, Douglas Frank wrote:
> Hi all
> 
> On my network there are two routers, ---.1 and ---.2.  I added both as
> default gateways:
> 
> any add default gw ---.1           (obviously I'm keeping the
> any add default gw ---.2            1st 3 octets secret :-)
> 
> so that the last couple of lines output by "route" are:re:
> 
> default fddi-prod-r2.zk 0.0.0.0  UG    0      0        0 eth0
> default fddi-prod-r1.zk 0.0.0.0  UG    0      0        0 eth0
> 
> ...in the hope that if one of these goes down, I'm still good...
> 
> Am I kidding myself?  What's the kewl way to achieve reliability?

You do that using HSSP or VRRP depending on if you are using Cisco or
some other third party equipment.  You configure the two routers such
that if the primary goes down the secondary takes over using the same IP
and MAC addresses.  The whole swap over takes a few seconds so there may
be a few dropped packets but with TCP they get retried and everybody
keeps running.

I'm not even sure you are sending packets out to both devices and if you
are you could end up with other problems if one path ends up being
slower than the other.  The least problem is doubling the traffic.  
Worst problem is confusing your applications if they happen to get the
same packets twice and are not able to sort it out.

-- 
Scot L. Harris
webid at cfl.rr.com

I guess it was all a DREAM ... or an episode of HAWAII FIVE-O ...