Re: INE Workbook

I was having issues grasping this concept as well using IPX workbooks where
they have a similar scenario. Your post was very informative :)

On Fri, Aug 6, 2010 at 11:05 PM, Garth Bryden <
hacked.the.planet.on.28.8k.dialup_at_gmail.com> wrote:

> Hi Bilal,
>
> The SLA is sending icmp's to the configured IP address, which gives the SLA
> a state, I believe with icmpecho you can have three states "OK, timeout or
> over threshold" the OK means that the echo-reply returned within the
> configured time threshold, over threshold means it returned but outside of
> the threshold and timeout means that the device you are sending the icmp
> echo to is completely unreachable.
>
> You are then tracking these return codes with the enhanced object tracker,
> which is a separate function in IOS that is used to track things such as
> interface protocols, routes in routing table and ip sla... the ip sla
> support for enhanced object tracker however is not available in the ip base
> version of IOS..
>
> The enhanced object tracker was originally created to for HSRP I believe so
> it could track if an interface went down and force the backup gateway to
> takeover but grew into this beautiful beast we used today.
>
> So here in this example, we are configuring the enhanced object tracker to
> track the state of the IP SLA so when the IP SLA returned a code of DOWN
> the
> trackers state also changes to DOWN and vice versa.
>
> The Object tracker is then attached to the static route, the purpose of
> this
> is that IF the object tracker state is UP then the route will be installed
> into the route table, if the object tracker state is DOWN then the route
> will be removed from the route table...
>
> the RIP process is configured to conditionally inject a default route,
> based
> on the condition in the route-map that it is configured for, in this
> instance the condition in the route map is that the dummy route is in the
> routing table, if it is not in the routing table the default route will not
> be generated by RIP.
>
> You do not necessarily have to use a dummy route, you could use a static
> default route if you wished, it doesn't really matter the purpose of the
> objective is to show you that you can force RIP to advertise a default
> route
> based on a condition in a route map :-)
>
> and no one is ever a pain by trying to understand something we all have to
> learn somehow! :-)
>
> HTH
>
> Garth
>
> On Sat, Aug 7, 2010 at 1:31 PM, Bilal Hansrod <bilal.hansrod_at_gmail.com
> >wrote:
>
> > Thanks Garth,
> >
> > I still couldn't get my head around of using the dummy route. How come it
> > disappear from R4 routing table when I am unable to reach BB3. I did in
> past
> > used sla monitor on ASA but I was tracking my defaut route and switch to
> > backup route if the destination is unreachable.
> >
> > Sorry for the pain, but can I do without dummy route. Is it done via
> dummy
> > route, because I don't have static default route.'
> >
> > Thanks,
> >
> > Bilal
> >
> >
> > On Sat, Aug 7, 2010 at 2:55 PM, Garth Bryden <
> > hacked.the.planet.on.28.8k.dialup_at_gmail.com> wrote:
> >
> >> Hiya,
> >>
> >> They use a dummy which will be removed from the route table if the SLA
> >> fails.. this is because they need to use a static route to configure the
> >> tracking with... you could probably use a default route as the dummy
> route
> >> pointing to null0 since that is purpose of the advertisement anyway.. I
> >> guess it doesn't really matter as long as it doesn't leak into the rest
> of
> >> your routing domain or outside and doesn't affect your routing!
> >>
> >> On Sat, Aug 7, 2010 at 12:30 PM, Bilal Hansrod <
> bilal.hansrod_at_gmail.com
> >> > wrote:
> >>
> >>> Hi All,
> >>>
> >>> I was doing INE workbook 1 and was bit lost in one of the technology
> lab.
> >>> The topic is RIPv2 Reliable Conditional Default Routing in which I
> >>> couldn't
> >>> understand why DUMMY route was used to track the reachability of BB3.
> Any
> >>> thoughts -
> >>>
> >>> Bilal
> >>>
> >>>
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-- 
-Steve Di Bias
Blogs and organic groups at http://www.ccie.net