What is a cloned route ?

Jacob Fried

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Oct 2, 2000, 3:00:00 AM10/2/00

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I have got a new F50 and I installed 4.3.3 from scratch.
netstat -r output a static route which I have no idea where it came
from:

Destination Gateway Flags Refs Use If
PMTU Exp Groups
a.b.c.d e.f.g.h UGHW 2 ...
en0 .... ... ......

where a.b.c.d is an ip address external to my network (querying a whois
server, output that it belongs to a californian university addresses
pool)
e.f.g.h is my default gateway.
According to man pages W flag means that the route is a cloned route.
Can anybody please explain what a cloned route is, cloned from what, and
what it is good for? and why I cannot delete it ?
(when trying to delete it: Cannot delete an object from the device
configuration database.
chginet: Cannot delete route
(host,a.b.c.d, e.f.g.h) from CuAt
)

Thanks
Jacob Fried

Dean

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Oct 2, 2000, 3:00:00 AM10/2/00

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4.3.3 has the annoying tendency to keep host routes in the routing table.
If you want to get rid of them, you can flush the routing table, but host
routes are harmless unless you get enough to fill up your routing table or
soemthing.

Stefan Llabres

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Oct 2, 2000, 7:53:10 PM10/2/00

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Im not sure, but maybe that is a the auto mtu discovery feature (no
machine to test right now...)
Try if "no -o tcp_pmtu_discover=0" and/or "no -o udp_pmtu_discover=0"
solves that.

Bye, Steafan... . . .

Holger van Koll

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Oct 3, 2000, 3:00:00 AM10/3/00

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Jacob Fried schrieb:

>
> I have got a new F50 and I installed 4.3.3 from scratch.
> netstat -r output a static route which I have no idea where it came
> from:
>
> Destination Gateway Flags Refs Use If
> PMTU Exp Groups
> a.b.c.d e.f.g.h UGHW 2 ...
> en0 .... ... ......
>
> where a.b.c.d is an ip address external to my network (querying a whois
> server, output that it belongs to a californian university addresses
> pool)
> e.f.g.h is my default gateway.
> According to man pages W flag means that the route is a cloned route.
> Can anybody please explain what a cloned route is, cloned from what, and
> what it is good for? and why I cannot delete it ?
> (when trying to delete it: Cannot delete an object from the device
> configuration database.
> chginet: Cannot delete route
> (host,a.b.c.d, e.f.g.h) from CuAt
> )
>
> Thanks
> Jacob Fried

Jacob,

does your default route have a "c" flag?

Then mtu-discovery is enabled and the following will happen:

You access a.b.c.d . aix notices there is no direct/specific route;
so it has to take the default route.

So it does. Now it discovery the max. paket size of the route to that
host
for better performance. It has to save that info somewhere, so it
creates a special route to that host containing that mtu.
It creates a cloned route from the default-route.

Next time you access that host no mtu-discovery has to be done
as there is a specific route with a mtu value.

I dont know, however, why you cant delete that route...

Dr. Markus

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Oct 4, 2000, 3:00:00 AM10/4/00

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Hi,

> I dont know, however, why you cant delete that route...
>

The "unable to delete"-Message usually results from adding routes with
the "route add"-command
this is not the aix-way!
in aix you would do this with "smitty route" (which uses a chdev-command
towards device inet0)
hth,
regards, Markus

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