[CentOS] Network routes

Tue Jan 29 23:24:37 UTC 2008
Les Mikesell <lesmikesell at gmail.com>

Jason Pyeron wrote:
> I am unable to ping NE.TW.RKB.IP1 from an outside network. Other machines
> which do not have access or routes for NET.WOR.KA.0 respond just fine.
> 
> How do I get it to respond on both NET.WOR.KA.0 and NE.TW.RKB.0 given all
> default traffic should go through  NET.WOR.KA.1  unless it is in reply to
> traffic from NE.TW.KB.1 or there is an outage.

You probably want to remove the default route through NE.TW.KB.1 and add 
routes for the specific networks that you can reach though it.  Normally 
routing is done toward a destination network/address without regard to 
the route of a packet you might be replying to.  As for an 'outage', how 
do you define/detect the outage?  Normally if you want routes to be 
determined dynamically you would set up a routing protocol with the 
next-hop routers - or for simple failover the alternative gateway 
routers might be configured via hsrp or vrrp to have a floating IP 
address that the rest of the LAN uses as the default gateway address.

> [root at host20 ~]# route -n
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    Use
> Iface
> NET.WOR.KA.0    0.0.0.0         255.255.255.0   U     0      0        0 eth1
> 192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
> NE.TW.RKB.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
> 169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth1
> 0.0.0.0         NET.WOR.KA.1    0.0.0.0         UG    0      0        0 eth1
> 0.0.0.0         NE.TW.RKB.1     0.0.0.0         UG    20     0        0 eth0
> 

-- 
   Les Mikesell
    lesmikesell at gmail.com