[AusNOG] IOS router selection

[Joshua D'Alton]

seems to me CDP would be used/useful for this? At least from a l2
perspective which would be the case of outage 99% the time?

sent from android
On 05/05/2014 4:15 PM, "Chris Balmain" <chris at team.dcsi.net.au> wrote:

>  Erm... meant to say ARP/ping reachability verification is *not* used
> unless you tell it to...
>
>  On 05/05/14 16:12, Chris Balmain wrote:
>
> 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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