Hi,
Just read this on CCO:
Note: In IOS release 12.0T and later, RIP does not advertise the default
router if the route is not learned via RIP. Therefore, it may be necessary
to redistribute the route into RIP, or use the default-information originate
command.
http://www.cisco.com/en/US/partner/tech/tk365/tk554/technologies_tech_note09186a0080094374.shtml
Cheers,
Paresh.
Priscilla Oppenheimer 07/17/03 10:27AM
Zsombor Papp wrote:
At 10:19 PM 7/16/2003 +, Priscilla Oppenheimer wrote:
To be fair, I just checked, and Doyle didn't say anthing about
redistribution.
The example simply shows configuring
ip route 0.0.0.0 0.0.0.0 192.168.1.82
The text says that the router that has that config (which is
running RIP by
the way) advertises the default to other RIP routers.
It goes on to say:
After a default route is identified in the routing table,
RIP, EIGRP, IGRP
will automatically advertise it.
That's right, isn't it?
I don't think so. That's what the original poster questioned
and I agree
with him. If it is right, then I take back everything.
RIP does automatically advertise a default route on my routers. Check this
out:
Albany#show ip route
Gateway of last resort is 10.10.0.2 to network 0.0.0.0
10.0.0.0 255.255.255.0 is subnetted, 1 subnets
C 10.10.0.0 is directly connected, Ethernet0
172.16.0.0 255.255.255.0 is subnetted, 2 subnets
C 172.16.50.0 is directly connected, Ethernet1
C 172.16.20.0 is directly connected, TokenRing0
R* 0.0.0.0 0.0.0.0 [120/1] via 10.10.0.2, 00:00:06, Ethernet0
Albany learned that last route from another router that is configured for
RIP on their shared network and has a static route that points to another
router. I didn't configure redistribution.
But, alas, this didn't work on IGRP or EIGRP.
So if anyone has a good errata for Doyle, Volume I, is this in it?
Priscilla
Well, except that about BGP, there I am 100% sure nothing
happens
automatically. :)
If it were OSPF you would need redistribution
And a 'default-info orig' as well.
Thanks,
Zsombor
, but
not for those others?
That was the original question. Sorry I confused it with the
statement from
CertZone, which really meant to cover a different situation.
:-)
Thanks,
Priscilla
John Neiberger wrote:
Zsombor Papp 7/16/03 3:42:18 PM
I looked at that page in Doyle's book and I thought it's
just
a simple
mistake, or maybe IOS changed since he wrote that, but
after
reading
this:
Handling of default routes varies from protocol to
protocol. RIP, IGRP,
EIGRP and BGP automatically redistribute default routes
while OSPF and
IS-IS
require you to explicitly advertise them with the
default-information
originate statement in your router configuration.
I start to think that these folks (Doyle included) have
some
basic problem
with simple terminology.
Actually this terminology might not be that simple after
all,
as it is not
clear whether something was redistributed unless it is
advertised to peers.
So revised statement below.
Also, I just realized that my above sentence sounds less
respectful than I
intended, so I thought I would mention that I learnt a lot
from Routing
TCP/IP and it's probably the most useful networking book
I've
ever read.
There is no way BGP automatically redistributes default
routes.
However it's true that OSPF and ISIS don't advertise the
default route
even if it's redistributed into them, unless
'default-information
originate' is specified.
So the statement should be something like RIP, IGRP,
EIGRP
and BGP
automatically advertise default routes that are
redistributed
into them,
while OSPF and ISIS require the 'default-information
originate'
statement. At least I hope that this is a true
statement...
:)
Probably this one is better:
RIP, IGRP, EIGRP and BGP automatically accept default
routes
that are
redistributed into them, while OSPF and ISIS silently
reject
the
redistributed default route unless 'default-information
originate' is
configured.
Thanks,
Zsombor
Actually, I think I wrote that line and it is a little
confusing, perhaps. I
took great care to be specific with my terminology but it's
easy to slip
back into bad habits from time to time. Many people use
terms
in a haphazard
way (like redistribute, advertise, originate, export,
import,
accept)
without fully considering the implications of using one term
over another.
With Howard's approval perhaps we should have CZ update that
line with your
edited version! I like your version better, anyway. :-)
Thanks,
John
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7i=72448t=72211
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