SUMMARY : Availability of dynamic route in Solaris 2.5

From: Rahul Roy (
Date: Mon Mar 18 1996 - 08:36:38 CST

Rahul Roy Voice: (609) 727-4600 Ext.265
Professional Services Group Email:
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The summary follows.....I got a lot of me too's, some
chastisement (unusual !!), and as usual - a lot of help ...thank you all
once original posting was as follows :

Hi Managers !!

Here is the situation - all machines are running Solaris 2.5..there are
two machines which do the routing. Now if one router were to die on me, I
want the routing requests to be automatically sent to the other Solaris
router. How would I achieve this ?? On the machine requesting a route ??
On the actual machines configured as routers ?? I look forward to hearing
from you....

And here are the responses :

Just use the default standard routing setup (ie no default route). If
one router goes down then the system will get a router info protocol
packet (RIP)from the other device to tell it about alternate routes.

Glenn Satchell

From: "Daniel J Blander - Sr. Systems Engineer for ACS"

This is what metrics are for. RIP has a facility that allows you
to specify specific routing with preferences set for each route.
These preference settings are called "metrics". They work (on
Sun systems at least) on all routes except the "default" route.


NetA NetB

Router A --------------------->

Router B ---------------------->

Using Solaris (or SunOS):

route add net 3

route add net 5
                                higher metric

The lower the metric, the more preference it is given for
forwarding packets. If that route is found to be unavailable
then the second route is used. A metric of 16 is used (or set)
when a route is unavailable. RIP has some problems though.
The more routes and secondary backup routes, the longer it
takes for failures to make themselves known and for your
secondary routes to take over. RIP works, just not very
quickly. It make take anywhere from 30 seconds to 15 minutes
for a route to "fail-over". Sun routing is not super robust
at this - and nor is RIP. (obviously a router like a Cisco
helps but the limitations of RIP still exist) OSPF is much
quicker but also only supported on "real" routers....


I don't have a 2.5 machine to check this, but I think the
/etc/defaultrouter file can contain multiple hostnames.



Daniel's suggestion seemed to be the best and I think I will
adopt it...I have not tried what Jeff suggested, so I cannot
comment on that......once again, thanks to everyone...



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