From: Keith Kruepke (lister@xxxxxxxxxxx)
Date: Thu Aug 10 2000 - 21:32:14 GMT-3
Yes, it would still work with a /28, as long as both protocols are using the sa
me classful network. Here is an example of how RIP works (this is independent
of redistribution):
Router1:
E0: 172.16.1.1/24
E1: 172.17.1.1/24
S0: 172.16.2.1/24
(Note that these are all subnets of two Class B networks.)
If Router1 is running RIP on both 172.16.0.0 and 172.17.0.0 networks, the follo
wing would be advertised across S0:
172.16.1.0
172.17.0.0
There are no masks in a RIP update, so I left them off here. The receiving rou
ter interprets these as 172.16.1.0/24 and 172.17.0.0/16. How does it decide wh
at masks to use? If the destination is in the same classful network as on the
receiving interface (172.16.0.0 in this case), then the router assumes that the
subnet mask is the same on the receiving interface. If it is in a different c
lassful network, the router assumes the route applies to the classful network,
rather than a subnet. The sending router uses this same logic when sending upd
ates--any routes to networks in a different classful network than the sending i
nterface are summarized at the classful boundary (which is why Router1 would se
nd 172.17.0.0 rather than 172.17.1.0).
I hope this helps,
Keith
----- Original Message -----
From: "Sam Munzani" <sam@chinet.com>
To: <Lachlan_Kidd@data3.com.au>
Cc: "Dayong Gan" <dgan@nuvo.com>; <ccielab@groupstudy.com>
Sent: Thursday, August 10, 2000 6:04 PM
Subject: Re: redistribute from Classless to Classful
Question:
Does that mean you can have /28 on RIP and OSPF and still it would work? I
thought RIP would work with classful boundries only.
Sam
On Fri, 11 Aug 2000 Lachlan_Kidd@data3.com.au wrote:
>
> To get this route to appear, you need to have a consistent mask throughout
> the network (i.e. /22) on your R2-R3 interfaces.
> Regards,
> Lachlan
>
>
>
>
>
> Dayong Gan
> <dgan@nuvo.co To: "'ccielab@groupstudy.com'" <
ccielab@groupstudy.com>
> m> cc:
> Sent by: Subject: redistribute from Class
less to Classful
> nobody@groups
> tudy.com
>
>
> 11/08/00
> 12:23 AM
> Please
> respond to
> Dayong Gan
>
>
>
>
>
> Hi, All.
>
> I have a problem here.
>
> R1---------------------R2--------------------R3
> OSPF RIP
>
>
> R1 has a route 172.16.1.0/22. R2-R3 uses 172.16.10.0/24. How can I make the
> R3 get the route 172.16.1.0. It's better not to use static route.
>
>
> Best regards,
>
>
> Dayong Gan
> Network Engineer
> Nuvo Network Management Inc.
> 260-2650 Queensview Drive, Ottawa. Canada K2B 8H6
> Tel:(613)721-6886 ext. 149
> Fax:(613)721-1399
> Email: dgan@nuvo.com
> http://www.nuvo.com
>
>
>
>
>
>
>
>
>
>
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