From: Fred Ingham (fningham@xxxxxxxxxxxxxxxx)
Date: Fri Dec 08 2000 - 15:10:14 GMT-3
resend of message
>
> To have this work you would have to redistribute rip subnets into ospf
> since summary-address is for external routes only. If you look at the
> routing table you will see the summary-address command generates the
> same 128.1.35.0 /24 to null 0. It does work.
>
> The config is
> router ospf 1
> summary-address 128.103.35.0 255.255.255.0
> redistribute rip subnets
> network 128.103.35.0 0.0.0.255 area 0
>
> router rip
> redistribute ospf 1 metric 3
> network 128.103.0.0
>
> Where the RIP domain is 128.103.36.0/24 and the OSPF domain is
> 128.103.35.0/28.
>
> A simplier way for this example is to use the default-information
> originate under RIP:
>
> The config is:
> router ospf 1
> redistribute rip subnets
> network 128.103.35.0 0.0.0.255 area 0
>
> router rip
> network 128.103.0.0
> default-information originate
>
> This doesn't work for IGRP.
>
> Cheers, Fred.
>
> "Connary, Julie Ann" wrote:
> >
> > Hi All,
> >
> > I have noticed in the tech tips when redistributing between classfull and
> > classless protocols
> > it uses static routes to null 0 to overcome different subnet mask lengths.
> >
> > http://www.cisco.com/warp/public/105/52.html
> >
> > Changing the subnet mask of the OSPF domain is difficult, so instead add a
> > static route in Router GW-2 that points to the OSPF domain with a mask of
> > 255.255.255.0,
> > but with a next hop of null0. Then, redistribute static routes into RIP.
> > Here's how to do it:
> >
> > ip route 128.103.35.0 255.255.255.0 null0
> > router rip
> > redistribute static
> > default metric 1
> >
> > This allows 128.103.35.0 to be advertised through RIP out the E2/0
> > interface of Router GW-2. However, Router GW-2 still has more specific
> > routes learned from OSPF
> > in its routing table, so the best routing decisions will be made.
> >
> > My question is, if the OSPF routes are more specific like in the first
> > example shown above (i.e. longer subnet masks) than say the
> > RIP routes is it valid to use a summary-address in the OSPF ASBR vs. a
> > static route to null 0?
> >
> > The config for the example might be:
> >
> > router ospf 1
> > network 128.103.35.0 0.0.0.255 area 0
> > summary-address 128.103.35.0 255.255.255.0
> >
> > router rip
> > network 128.103.0.0
> > redistribute ospf metric 1
> >
> > Julie Ann
> >
> > ------------------------------------------------------------------------
> > Julie Ann Connary
> > | | Network Consulting Engineer
> > ||| ||| Federal Support Program
> > .|||||. .|||||. 13635 Dulles Technology Drive,
> > Herndon VA 20171
> > .:|||||||||:.:|||||||||:. Pager: 1-888-642-0551
> > c i s c o S y s t e m s Email: jconnary@cisco.com
> >
> > ------------------------------------------------------------------------
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