[c-nsp] Different behaviour for static route on different IOS?

[Oliver Boehmer (oboehmer)]

Hi,

just tried with 12.0(27)S3, and I don't see the problem.. not sure what
happened in your case.. can you try a more recent 12.0S release?

PE1#sh run | i ip route
ip route 193.0.0.0 255.255.255.0 192.168.201.2
PE1#
PE1#sh ip route 193.0.0.0
Routing entry for 193.0.0.0/24
  Known via "static", distance 1, metric 0
  Routing Descriptor Blocks:
  * 192.168.201.2
      Route metric is 0, traffic share count is 1

PE1#sh ip route 192.168.201.2
Routing entry for 192.168.201.0/24
  Known via "connected", distance 0, metric 0 (connected, via interface)
  Routing Descriptor Blocks:
  * directly connected, via Loopback10
      Route metric is 0, traffic share count is 1

PE1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
PE1(config)#int lo10
PE1(config-if)#shut
PE1(config-if)#^Z
PE1#
*Feb 18 17:36:23.019: RT: interface Loopback10 removed from routing
table
*Feb 18 17:36:23.019: RT: del 192.168.201.0 via 0.0.0.0, connected
metric [0/0]
*Feb 18 17:36:23.019: RT: delete network route to 192.168.201.0
*Feb 18 17:36:24.039: IP-Static:  193.0.0.0 255.255.255.0 192.168.201.2
*Feb 18 17:36:24.871: %LINK-5-CHANGED: Interface Loopback10, changed
state to administratively down
*Feb 18 17:36:25.891: %LINEPROTO-5-UPDOWN: Line protocol on Interface
Loopback10, changed state to down
PE1#
PE1#sh ip route 193.0.0.0    
Routing entry for 193.0.0.0/24
  Known via "static", distance 1, metric 0
  Routing Descriptor Blocks:
  * 192.168.201.2
      Route metric is 0, traffic share count is 1

PE1#sh ip route 192.168.201.2
Routing entry for 192.168.0.0/16, supernet
  Known via "ospf 1", distance 110, metric 20, type extern 2, forward
metric 128
  Last update from 10.1.1.2 on Serial3/0, 00:00:44 ago
  Routing Descriptor Blocks:
  * 10.1.1.2, from 10.0.0.3, 00:00:44 ago, via Serial3/0
      Route metric is 20, traffic share count is 1

PE1#


	oli

chooweikeong at pacific.net.sg <> wrote on Friday, February 18, 2005 7:07
AM:

> Hi All,
> 
> Have to bring this up again, as i still cant conclude the exact
> behaviour 
> of static route. From what i observe, this "problem" (suppress
> recursive 
> static route) happens even the prefix and next-hop is not in the same
> supernet...
> 
> 
> IOS (tm) 7200 Software (C7200-K4P-M), Version 12.0(22)S5, EARLY
> DEPLOYMENT RELEASE SOFTWARE (fc1)
> 
> interface Serial6/0
>   ip address 192.154.x.x 255.255.255.252
>   no ip directed-broadcast
>   shutdown
>   no cdp enable
> 
> ip classless
> ip route 203.120.x.x 255.255.255.252 192.154.x.x
> 
> #sh ip in brief | in 192.154.x
> Serial6/0           192.154.x.x   YES manual administratively down
> down 
> 
> #sh ip route 203.120.x.x
> % Subnet not in table
> 
> #sh ip route 192.154.x.x
> Routing entry for 192.154.x.x/21, supernet
>    Known via "ospf 10", distance 110, metric 20, type extern 2,
> forward metric 1 
> 
> 
> Hope you guys can help me out. Thanks.
> 
> Rgds,
> Wei Keong
> 
> 
> On Wed, 16 Feb 2005, Gert Doering wrote:
> 
>> Hi,
>> 
>> On Wed, Feb 16, 2005 at 10:51:17AM +0100, Oliver Boehmer (oboehmer)
>> wrote: 
>>>> Indeed, it's not "classful", but a more generic check "if the route
>>>> prefix *and* the gateway IP are part of the *same* supernet route
>>>> (/16, default route, ...) --> suppress recursive static route".
>>> 
>>> coz it wouldn't make much sense, would it?
>>> 
>>> you learn 192.168/16 via POS0/0, and you enter a static route for
>>> 192.168.20/24 pointing to a nexthop within 192.168/16, all traffic
>>> to 192.168/16 (including 192.168.20/24) would still go out POS0/0.
>> 
>> Well.  There is something to be said for this...
>> 
>>> because it adds routing information.. I don't really find this
>>> surprising..
>> 
>> ... but usually the box doesn't check "does it add any useful
>> information 
>> if I put this route into service" either.
>> 
>> Like in:
>> 
>>  ip route 192.168.0.0 255.255.0.0 pos0/0
>>  ip route 192.168.20.0 255.255.255.0 pos0/0
>> 
>> -> you'll see *both* routes in the RIB and FIB, even if the second
>> route "doesn't add routing information" either...
>> 
>> But whatsoever - I'm not trying to criticise (today :) ), I was just
>> explaining my surprise, and now I have understood what's going on.
>> 
>> gert
>> --
>> USENET is *not* the non-clickable part of WWW!
>>                                                          
>> //www.muc.de/~gert/ Gert Doering - Munich, Germany                  
>> gert at greenie.muc.de fax: +49-89-35655025                       
>> gert at net.informatik.tu-muenchen.de 
>> 
> 
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