From: Scott Morris (swm@emanon.com)
Date: Thu May 24 2007 - 12:22:54 ART
That would be correct. :)
_____
From: Vince Mashburn [mailto:cciegroupstudy@gmail.com]
Sent: Thursday, May 24, 2007 10:34 AM
To: Scott Morris
Cc: Salau,Olayemi; Radioactive Frog; ccielab@groupstudy.com
Subject: Re: IP route 0.0.0.0 vs 255.255.255
a /32 does not make any since for a quad 0 entry. It means that the router
would be looking for an exact match for a destination address 0.0.0.0, not a
default route.
On 5/24/07, Scott Morris <swm@emanon.com> wrote:
I think the effect would be COMPLETELY different:
R1(config-if)#do sh ip ro
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static
route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
<http://140.101.0.0/24> 140.101.0.0/24 is subnetted, 3 subnets
C 140.101.35.0 is directly connected, FastEthernet0/0
C 140.101.36.0 is directly connected, FastEthernet0/1
C 140.101.1.0 is directly connected, Loopback0
R1(config-if)#do ping 10.10.10.10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.10.10, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R1(config-if)#do debug ip pack
IP packet debugging is on
R1(config-if)#do ping 10.10.10.10 re 2
Type escape sequence to abort.
Sending 2, 100-byte ICMP Echos to 10.10.10.10, timeout is 2 seconds:
*May 24 13:27:17.991: IP: s= 140.101.1.1 <http://140.101.1.1> (local),
d=10.10.10.10, len 100,
unroutable.
*May 24 13:27:19.991: IP: s=140.101.1.1 (local), d=10.10.10.10
<http://10.10.10.10> , len 100,
unroutable.
Success rate is 0 percent (0/2)
R1(config-if)#ip route 0.0.0.0 255.255.255.255 140.101.35.5
<http://140.101.35.5>
R1(config)#do ping 10.10.10.10 re 2
Type escape sequence to abort.
Sending 2, 100-byte ICMP Echos to 10.10.10.10, timeout is 2 seconds:
*May 24 13:27:42.655: IP: s=140.101.1.1 (local), d=10.10.10.10, len 100,
unroutable.
*May 24 13:27:44.655: IP: s=140.101.1.1 <http://140.101.1.1> (local),
d=10.10.10.10, len 100,
unroutable.
Success rate is 0 percent (0/2)
R1(config)#do sh ip ro | in 0.0.0.0
S 0.0.0.0/32 <http://0.0.0.0/32> [1/0] via 140.101.35.5
R1(config)#ip route 0.0.0.0 0.0.0.0 140.101.35.2
R1(config)#do sh ip ro | in 0.0.0.0
Gateway of last resort is 140.101.35.2 to network 0.0.0.0
S 0.0.0.0/32 [1/0] via 140.101.35.5
S* 0.0.0.0/0 [1/0] via 140.101.35.2
R1(config)#do ping 10.10.10.10 re 2
Type escape sequence to abort.
Sending 2, 100-byte ICMP Echos to 10.10.10.10, timeout is 2 seconds:
*May 24 13:28:16.719: IP: tableid=0, s=140.101.35.1 <http://140.101.35.1>
(local), d=10.10.10.10
(FastEthernet0/0), routed via RIB
*May 24 13:28:16.719: IP: s=140.101.35.1 (local), d=10.10.10.10
<http://10.10.10.10>
(FastEthernet0/0), len 100, sending
*May 24 13:28:16.719: IP: s=140.101.35.1 (local), d=10.10.10.10
(FastEthernet0/0), len 100, encapsulation failed.
*May 24 13:28:18.719: IP: tableid=0, s=140.101.35.1 (local), d=10.10.10.10
(FastEthernet0/0), routed via RIB
*May 24 13:28:18.719: IP: s= <http://140.101.35.1> 140.101.35.1 (local),
d=10.10.10.10
(FastEthernet0/0), len 100, sending
*May 24 13:28:18.719: IP: s=140.101.35.1 (local), d= 10.10.10.10
<http://10.10.10.10>
(FastEthernet0/0), len 100, encapsulation failed.
Success rate is 0 percent (0/2)
R1(config)#
-----Original Message-----
From: nobody@groupstudy.com <mailto:nobody@groupstudy.com>
[mailto:nobody@groupstudy.com] On Behalf Of
Salau,Olayemi
Sent: Thursday, May 24, 2007 5:08 AM
To: Radioactive Frog; ccielab@groupstudy.com
<mailto:ccielab@groupstudy.com>
Subject: RE: IP route 0.0.0.0 vs 255.255.255
Hello Frog,
0.0.0.0 0.0.0.0 means default route out thru 2.2.2.2 0.0.0.0 255.255.255.255
means any destination route out thru 2.2.2.2
The first is like generating or originating default route towards the
destination while the second is just matching any destination route not
included in the RIB.
The router will prefer to use the default route (/0 over /32) if you have
both in the RIB. This behaviour is reverse of the longest prefix match for
dynamic routing.
In the case the interface using the /0 is down, then it uses the route via
the interface through /32
Many Thanks
This archive was generated by hypermail 2.1.4 : Fri Jun 01 2007 - 06:55:22 ART