From: Vince Mashburn (cciegroupstudy@gmail.com)
Date: Thu May 24 2007 - 11:34:22 ART
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
>
> 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 (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, 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
> 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 (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 [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 (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
> (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=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
> (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] On Behalf Of
> Salau,Olayemi
> Sent: Thursday, May 24, 2007 5:08 AM
> To: Radioactive Frog; 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
> _________________________________________________
> Olayemi Salau
> Network Analyst
> I.T. Solutions Division
> Southampton City Council
> ( 023 8083 4070 7 077 8811 2036 3 079 5825 7509
> * olayemi.salau@southampton.gov.uk
> _________________________________________________
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Radioactive Frog
> Sent: 24 May 2007 07:35
> To: Cisco certification
> Subject: IP route 0.0.0.0 vs 255.255.255
>
> Hi Group,
> What and where is the scenario when we should use:
>
> ip route 0.0.0.0 0.0.0.0 <next hop ip>
> Vs.
> ip route 0.0.0.0 255.255.255.255 <next hop ip>
>
> What if I do on a router both route? For example:
>
> ip route 0.0.0.0 0.0.0.0 2.2.2.2
> ip route 0.0.0.0 255.255.255.255 2.2.2.2
>
> Frog
>
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