[AusNOG] IOS router selection

[Chris Balmain]

The route is installed in the FIB if the router has a route to the 
gateway itself (e.g. via a connected interface in up/up status, or 
recursively via IGP etc)

ARP/ping reachability verification is used unless you tell it to (on 
Cisco via "ip sla" - 
http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/813-cisco-router-ipsla-basic.html)

CB

On 05/05/14 15:58, Alex Samad - Yieldbroker wrote:
> Hi
>
> I am looking for some documentation that explains the way cisco behaves.
>
> If I have this
>
> IOS
> ip route 0.0.0.0 0.0.0.0 w.x.y.z 230
> ip route 0.0.0.0 0.0.0.0 f.g.h.i  240
> ip route 0.0.0.0 0.0.0.0 r.s.t.u 250
>
> ASA
> route internet 0.0.0.0 0.0.0.0 w.x.y.z 230
> route internet 0.0.0.0 0.0.0.0 f.g.h.i 240
> route internet 0.0.0.0 0.0.0.0 r.s.t.u 250
>
>
> this tells me the default gateway used is w.x.y.z, unless that gateway is unavailable or dead..
>
> I am looking at how Cisco decides when a gateway is dead, I found documents on route selection, but nothing that specifically address dead gateways
>
> I presume, and from what I have seen if there is no arp its dead..
>
> Thanks
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