From: Rick (ccie_2003@hotmail.com)
Date: Sun Oct 06 2002 - 15:21:37 GMT-3
The secondary addressing is not working for me with this. I have a /25
connecting from my rip domain to OSPF ASBR and the rest of all routes are
/24s. Do you have turn of split horizon on both sides of the serial link and
put the secondary address on both sides? I have read all I can find about
this but I must be missing something because it is not working correctly for
me. Can some please explain the viable tools to perform this task between
VLSM and FLSM?
Thanks,
Rick
----- Original Message -----
From: "Baety Wayne SrA 18 CS/SCBX" <Wayne.Baety@kadena.af.mil>
To: <ccielab@groupstudy.com>
Sent: Thursday, October 03, 2002 4:03 AM
Subject: RE: What if OSPF routes have shorter masks than RIP?
> Answers inline (bracketed)....
>
> WAYNE A. BAETY, SRA, MCSE, USAF
> 18th Communications Squadron
> DSN: 634-9927
> Commercial: 011 81 611 734 9927
>
>
>
> -----Original Message-----
> From: Hunt Lee [mailto:huntl@webcentral.com.au]
> Sent: Thursday, October 03, 2002 3:51 PM
> To: 'Bruce Williams'
> Cc: 'Young K. Bae'; 'Chris Hugo'; 'Donny MATEO'; 'Baety Wayne SrA 18
> CS/SCBX'; 'folivore'
> Subject: RE: What if OSPF routes have shorter masks than RIP?
>
>
> Hello,
>
> I have read through the entire thread for 3 times already. However, I'm
> still not so clear on what are the 4 solutions that Wayne proposed, can
> someone please kindly explain to me??
>
> 1st Solution:
>
> On both the interfaces connecting between R1 & R2, use a secondary IP from
> the 172.16.0.x/25 network, so the RIP network will have the same subnet
mask
> as OSPF network (this I understand)
>
> 2nd Solution:
>
> [[[[[[[[[[
>
> Read solution 3 carefully and understand the principles before reading
this.
>
>
> RIP will automatically translate all subnet advertisements received from
one
> classful network into a single advertisement containing only that classful
> network when advertised to another classful network. It is sorta like
> aggregating an address with BGP, except you have no control over the
> aggregation.
>
> For instance, when 172.16.200.0/25 is advertised from one router unto a
RIP
> enabled interface of another router that has an address like
172.17.201.1/25
> since 172.16 is a different classful network thatn 172.17, all subnets
> pertaining to 172.16/16 (including 172.16.200.0/25) will be pruned from
the
> update and replaced with a single advertisement of 172.16.0.0/16. This is
> called a subnet default route. You can use this feature of RIP to your
> advantage by using a different classful network prefix in your RIP domain
> than your OSPF domain. Your OSPF domain will send this subnet default
route
> to your RIP domain, and your RIP domain will maintain reachability to that
> classful network.
>
> -Wayne
>
> ]]]]]]]]]]
>
> Assign it with a completely different classful (or classless??) network
for
> the RIP domain
>
> e.g. 192.168.1.0 /24
>
> Problem 1) I have tried to set the RIP network as a Classful network
> (192.168.1.0/24) & classless network (192.168.1.0 /28) & they both work...
> so isn't sure what Wayne means by using a "classful network altogether"
>
> Problem 2) I tried to turn on / off RIP's auto-summarization by "no
> auto-summary" / "auto-summry" under RIP process and once again, they both
> work too... so again wasn't sure what Wayne means by "relying on
> auto-summarization & advertisement of the classful network"
>
>
> 3rd Solution:
>
> [[[[[[[[[[[
>
> Your ospf domain had the network 172.16.200.0/25 advertised, yet your RIP
> domain only understands /26 sized subnets of 172.16/16, other classful
> networks (e.g. 172.17/16, 172.18/16, etc), and the default route
(0.0.0.0).
> Translate 172.16.200.0/25 into 2 different sized /26 subnets and your RIP
> domain will then understand it.
>
> This could be accomplished with this....
> (Example 1)
>
> ip route 172.16.200.0 255.255.255.192 eth0
> ip route 172.16.200.64 255.255.255.192 eth0
>
> Or This...
> (Example 2)
>
> ip route 172.16.200.0 255.255.255.192 [next-hop ip address]
> ip route 172.16.200.64 255.255.255.192 [next-hop ip address]
>
> However, as you have stated you cannot use static routes. Therefore slap
> those networks on an interface in your OSPF domain as secondaries. It
will
> have the same effect as making a static to an interface as shown in
Example
> #1. This will make those nextworks appear to your routing process as
being
> directly connected. That means your router will ARP for those networks as
> though they appeared on the connected medium. However, you've already
> defined that network somewhere else in your OSPF domain as
172.16.200.0/25.
> What will happen is that the router where on these statics are applied
> (example 1 style only) will send an ARP broadcast over the medium for any
> packets it receives falling within that range. Another router that sees
> these ARP broadcasts and has proxy-arp turned on will respond to these ARP
> broadcasts with its own interface address and offer to forward those
packets
> to their correct destination. This is called proxy ARPing and that's why
> you would need proxy-arp turned on.
>
> -Wayne
>
> ]]]]]]]]]]
>
> "He could also subdivide the smaller size prefix with secondary networks
> into multiple networks that match the larger subnet size of the RIP domain
> (3rd Solution). To get this into the routing table static addressing
would
> be the the preferred method but using secondaries on one of the router
links
> in the OSPF domain and relying on proxy-arp to determine destination
> next-hop would also work."
>
> I'm completely loss =( not sure wot Wayne is referring to here?!? What
> are the smaller size prefix / larger subnet size of RIP domain??? And
what
> static addressing is Wayne referring to?
>
>
> 4th Solution:
>
> [[[[[[[[[[
>
> Solution 4 is exactly like solution 1 except you use a tunnel connection
to
> interconnect your routers thereby avoiding the necessity to "pathing" your
> routing information throughout your network.
>
> Once you research and understand how to work with just creating simple
> tunnel interfaces, you'll know what we mean. You'll get an a-ha.
>
> ]]]]]]]]]]
>
> "A 4th Solution (that was mentioned) is to create a tunneled interface
> matching the subnet size of the RIP domain with the endpoint of the tunnel
> running to each RIP router requiring reachability information about that
> subnet size."
>
> I haven't used any Tunnel interface before. Can someone kindly give me
some
> e.g. here? How would I do it for Young's e.g.?
>
>
> Thanks.
>
> Best Regards,
> H.
>
>
>
>
> -----Original Message-----
> From: Bruce Williams [mailto:bwilliams175@comcast.net]
> Sent: Wednesday, 2 October 2002 1:31 PM
> To: Donny MATEO
> Cc: ccielab@groupstudy.com
> Subject: RE: What if OSPF routes have shorter masks than RIP?
>
>
> Split Horizon should be disabled on the interface that has the secondary
> address so that both networks can be advertised out the interface.
>
> Check out this link on secondary addresses and split horizon.
> http://www.cisco.com/warp/public/105/41.html
>
> Bruce
>
> -----Original Message-----
> From: Donny MATEO [mailto:donny.mateo@sg.ca-indosuez.com]
> Sent: Tuesday, October 01, 2002 11:12 PM
> To: Bruce Williams
> Cc: ccielab@groupstudy.com
> Subject: RE: What if OSPF routes have shorter masks than RIP?
>
>
>
> Could you be more specific on which issue. If it's a routing feedback from
> the other router, for most interface split-horizon is enabled. The only
> execption i know and had accountered so far is the physical serial
interface
> for frame-relay. Do let me know if you found other issues. I'll try to lab
> it again tonight.
>
> Donny
>
>
>
> Bruce Williams
> <bwilliams175@com To: Donny MATEO
> <donny.mateo@sg.ca-indosuez.com>, Richard Davidson
> cast.net> <rich@myhomemail.net>
> Sent by: cc:
> ccielab@groupstudy.com
> nobody@groupstudy Subject: RE: What if OSPF
> routes have shorter masks than RIP?
> .com
>
>
> 02-10-2002 10:37
> Please respond to
> Bruce Williams
>
>
>
>
>
>
> If you use secondary addresses, how do you deal with the split horizon
> issue?
>
> Bruce
>
>
> -----Original Message-----
> From: Baety Wayne SrA 18 CS/SCBX [mailto:Wayne.Baety@kadena.af.mil]
> Sent: Wednesday, 2 October 2002 12:55 PM
> To: 'folivore'; Baety Wayne SrA 18 CS/SCBX; 'Young K. Bae';
> ccielab@groupstudy.com
> Subject: RE: What if OSPF routes have shorter masks than RIP?
>
>
> So far 4 solutions that work...
>
> Yes, what you've stated is called tunnelling the subnet with secondaries
> (1st Solution). That would work in this instance because there is only 1
> router in his diagram involved on the RIP side. It's viable as long as he
> remembers to place a secondary network throughout his RIP domain on each
> router link (sorta like creating a path) to maintain connectivity and
> reachability information about that particular subnet size. (RIP silently
> drops information about subnets across subnets with a differing subnet
size
> but part of the same classful network). It may be better to use a
different
> classful network altogether (2nd Solution) and rely on auto-summarization
> and advertisement of the classful network. He could also subdivide the
> smaller size prefix with secondary networks into multiple networks that
> match the larger subnet size of the RIP domain (3rd Solution). To get
this
> into the routing table static addressing would be the the preferred method
> but using secondaries on one of the router links in the OSPF domain and
> relying on proxy-arp to determine destination next-hop would also work.
> Solution 2 and 3 require modification of relatively a few routers and
> probably can be more easily documented than Solution 1. A 4th Solution
> (that was mentioned) is to create a tunneled interface matching the subnet
> size of the RIP domain with the endpoint of the tunnel running to each RIP
> router requiring reachability information about that subnet size. This is
> really just Solution 1 with performance drawbacks for the sake of
> convenience and possibly smaller subnet utilization (if every router
doesn't
> require reachability information). Both Solution 1 and 4 require
> provisioning a new subnet for each router link just for the sake of
carrying
> information about subnets that have a different subnet size in the routing
> table: something that can be quite wasteful if deployed in a large scale
> fashion.
>
> WAYNE A. BAETY, SRA, MCSE, USAF
> 18th Communications Squadron
> DSN: 634-9927
> Commercial: 011 81 611 734 9927
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Donny
> MATEO
> Sent: Tuesday, October 01, 2002 10:04 PM
> To: Richard Davidson
> Cc: ccielab@groupstudy.com; nobody@groupstudy.com
> Subject: RE: What if OSPF routes have shorter masks than RIP?
>
>
> I've tried this and yes it works.
> Care have to be taken though, I was testing on different IOS version and
> guess what...they all got different behaviour. Some works some don't. So,
it
> all depends on which IOS you are using.
>
>
> Donny
>
>
>
> Richard Davidson
> <rich@myhomemail. To:
> ccielab@groupstudy.com
> net> cc:
> Sent by: Subject: RE: What if OSPF
> routes have shorter masks than RIP?
> nobody@groupstudy
> .com
>
>
> 28-09-2002 11:11
> Please respond to
> Richard Davidson
>
>
>
>
>
>
> Would a secondary addresses on R2 and R1 in the range of 172.16.100.9/29
> work? Please let me know if it does. Rich "Young K. Bae" wrote:Hi Bob,
>
> The solution stated in the document requires static routes, which I'm not
> allowed to do. Is there any other way to accomplish the object without
using
> static routes?
>
> Thanks,
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > Bob Sinclair
> > Sent: Friday, September 27, 2002 7:17 PM
> > To: Young K. Bae; ccielab@groupstudy.com
> > Subject: Re: What if OSPF routes have shorter masks than RIP?
> >
> >
> > Try this link:
> >
> > http://www.cisco.com/warp/public/105/52.html
> >
> > It is ugly!
> >
> > ----- Original Message -----
> > From: "Young K. Bae"
> > To:
> > Sent: Friday, September 27, 2002 8:51 PM
> > Subject: What if OSPF routes have shorter masks than RIP?
> >
> >
> > > Guys,
> > >
> > > I'm sure this question has been asked many times before,
> > but can someone
> > > kindly explain to me again? There are some /25 routes in
> > OSPF Area0 that I
> > > need to redistribute into RIP v1. The serial link that
> > connects R1 with R2
> > > has a /26 mask. How can I inject /25 OSPF routes into a
> > classful routing
> > > domain in a case such as this?
> > >
> > > R1 --- 172.16.12.0/26 (RIPv1) --- R2 ---- 172.16.100.0/29
> > (Area1) --- R5
> > > 172.16.200.0/25 (Area0)
> > >
> > > Thanks in advance,
> > >
> > > Young
>
>
>
>
>
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> privileged material and may not be copied, redistributed or published (in
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