From: sanjay (ccienxtyear@xxxxxxxxxxx)
Date: Thu May 03 2001 - 21:59:51 GMT-3
Why not use "area range x.x.x.x " command on the ABR's. Works like a charm.
So if you have 170.100.4.1/27 in area 4 and 170.100.7.2/30 in area 3 on a
router running OSPF. You could use area 4 range 170.100.4.0 and area 3 range
170.100.7.0. Thus your IGRP router which is running 170.100.1.0/24 will be
able to ping all the interfaces on the OSPF routers. (after of course you do
a redistribution on the router that is running both routing protocols)
In the real lab, if this don't work, I would use static routes and take a
hit on the points. Atleast this way, I will be able to continue with the
rest of the lab and hopefully will have end to end connectivity in the end.
Just my 2 cents...
thanks,
Sanjay
----- Original Message -----
From: "Mas Kato" <tealp729@home.com>
To: "'Mask Of Zorro'" <ciscokid00@hotmail.com>
Cc: "'CCIELAB'" <ccielab@groupstudy.com>
Sent: Thursday, May 03, 2001 5:27 PM
Subject: RE: IP Default-Network/IP Subnet-Zero Exploit--or old news?
> Fair enough Z,
>
> But if the requirement in the lab is "ping all interfaces from all
> routers" in a similar OSPF VLSM/FLSM scenario--and the 'summary-address'
> hack doesn't work, inter-area summarization isn't appropriate and they
> take the 'ip default-network' command away, is there anything left
> besides static routes?
>
> I think I may lose points if I hand them a box of bubble-gum and bailing
> wire. <G>
>
> Mas
>
> -----Original Message-----
> From: Mask Of Zorro [mailto:ciscokid00@hotmail.com]
> Sent: Thursday, May 03, 2001 11:57 AM
> To: tealp729@home.com
> Subject: Re: IP Default-Network/IP Subnet-Zero Exploit--or old news?
>
>
> It is cool to watch all these talented people jump through flaming hoops
> to
> get this thing working... I am amazed at the many workarounds that I
> have
> seen that actually work! Nevertheless, I have to warn you, no matter how
> cool, no matter how elegent (or not, in some cases), your solution will
> NEVER EVER EVER be allowed to include the "ip default-network" command
> in
> the real lab... but in the real world, this is truly cool!
>
> Z
>
>
> >From: Mas Kato <tealp729@home.com>
> >Reply-To: Mas Kato <tealp729@home.com>
> >To: "'CCIELAB'" <ccielab@groupstudy.com>
> >Subject: IP Default-Network/IP Subnet-Zero Exploit--or old news?
> >Date: Wed, 02 May 2001 23:21:44 -0700
> >
> >Hello everybody,
> >
> >I've been playing around with the ole' FLSM network-to-VLSM network
> >reachability scenario and may have stumbled across an 'ip
> >default-network' / 'ip subnet-zero' exploit. It's a variation on
> >something I found in the archives--but I'm not sure if it's old news or
> >not, so I thought I'd throw it out there and have you guys rip it to
> >shreds...
> >
> >Major network: 172.16.0.0
> >
> >OSPF/28--(R3)--OSPF/24--(R5)--IGRP/24--(R2)
> >
> >Goal: Provide reachability to the OSPF/28 network from the IGRP/24
> >network while avoiding statics, blah, blah...
> >
> >One of the archived suggestions is to configure a classful loopback on
> >R5, have IGRP advertise it to R2 and then use the 'ip default-network'
> >command on R2, referencing the classful network. Fine--but what if
> we're
> >limited to using subnets from just one major network?
> >
> >Well, since the 'ip default-network' command is classful, if we
> >reference a subnet of our major network we get that lovely static route
> >installed to the major net and then we have to issue the 'ip
> >default-network' command again, this time referencing the major net.
> Ug.
> >
> >Here's what it looked like on R2:
> >
> >Gateway of last resort is 172.16.5.0 to network 172.16.0.0
> >
> > * 172.16.0.0/16 is variably subnetted, 6 subnets, 2 masks
> >C 172.16.52.0/24 is directly connected, Ethernet0
> >I 172.16.35.0/24 [100/7100] via 172.16.52.5, 00:00:13, Ethernet0
> >I 172.16.5.0/24 [100/1600] via 172.16.52.5, 00:00:13, Ethernet0
> >S* 172.16.0.0/16 [1/0] via 172.16.5.0
> >C 172.16.2.0/24 is directly connected, Loopback0
> >R2#
> >
> >But then I got to thinking, "yo, what if the subnet we reference is
> >subnet zero?"
> >
> >Now check out R2 (no static!):
> >
> >Gateway of last resort is 172.16.52.5 to network 172.16.0.0
> >
> > * 172.16.0.0/24 is subnetted, 5 subnets
> >C 172.16.52.0 is directly connected, Ethernet0
> >I 172.16.35.0 [100/7100] via 172.16.52.5, 00:01:16, Ethernet0
> >I* 172.16.0.0 [100/1600] via 172.16.52.5, 00:01:16, Ethernet0
> >C 172.16.2.0 is directly connected, Loopback0
> >R2#
> >
> >Analysis, feedback, gotchas, etc. welcomed...
> >
> >Regards,
> >
> >Mas Kato
> >
> >(Config snippets follow...)
> >
> >!!!!!!!!!!
> >hostname R5
> >!
> >ip subnet-zero
> >!
> >interface Loopback0
> > ip address 172.16.0.5 255.255.255.0
> >!
> >interface Ethernet0
> > ip address 172.16.52.5 255.255.255.0
> >!
> >interface Serial1
> > bandwidth 2000
> > ip address 172.16.35.5 255.255.255.0
> >!
> >router ospf 1
> > log-adjacency-changes
> > redistribute igrp 1 metric 10 subnets route-map IGRPNETS
> > network 172.16.35.0 0.0.0.255 area 0
> >!
> >router igrp 1
> > redistribute ospf 1 metric 2000 2000 255 1 1500
> > passive-interface Serial1
> > network 172.16.0.0
> >!
> >ip classless
> >!
> >access-list 1 permit 172.16.0.0 0.0.0.255
> >access-list 1 permit 172.16.2.0 0.0.0.255
> >access-list 1 permit 172.16.52.0 0.0.0.255
> >route-map IGRPNETS permit 10
> > match ip address 1
> >!
> >end
> >R5#
> >
> >!!!!!!!!!!
> >R2#
> >hostname R2
> >!
> >ip subnet-zero
> >!
> >interface Loopback0
> > ip address 172.16.2.1 255.255.255.0
> >!
> >interface Ethernet0
> > ip address 172.16.52.2 255.255.255.0
> >!
> >router igrp 1
> > network 172.16.0.0
> >!
> >ip classless
> >ip default-network 172.16.0.0
> >end
> >R2#
> >**Please read:http://www.groupstudy.com/list/posting.html
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