Static routing problems

Is "ip classless" configured?
which version of ios are you using?

ip classless is configured. The IOS version is 12.4(1

static routes are only added to the routing table if the next hop can be reached or the interface is up depending on configuring the static with a next hop or exit interface.

ip route 1.0.0.0 255.0.0.0 20.1.1.1 next hop can't be reached thus it is not in the RIB

R1(config)#ip route 5.0.0.0 255.0.0.0 192.168.1.6 next hop cant be reached thus it is not int the RIB

S 2.0.0.0/8 [1/0] via 10.1.1.2
S 4.0.0.0/8 [1/0] via 192.168.1.2
these two recurse to an exit interface and the other 2 probably dont

S 2.0.0.0/8 [1/0] via 10.1.1.2
change this to a /16 and the other route will probably be added

kryolla wrote: »

static routes are only added to the routing table if the next hop can be reached or the interface is up depending on configuring the static with a next hop or exit interface.

ip route 1.0.0.0 255.0.0.0 20.1.1.1 next hop can't be reached thus it is not in the RIB

R1(config)#ip route 5.0.0.0 255.0.0.0 192.168.1.6 next hop cant be reached thus it is not int the RIB

S 2.0.0.0/8 [1/0] via 10.1.1.2
S 4.0.0.0/8 [1/0] via 192.168.1.2
these two recurse to an exit interface and the other 2 probably dont

S 2.0.0.0/8 [1/0] via 10.1.1.2
change this to a /16 and the other route will probably be added

I haven't really checked this out but, the first output had

R1(config)#do sh ip rou

Gateway of last resort is not set

S 1.0.0.0/8 [1/0] via 20.1.1.1
S 2.0.0.0/8 [1/0] via 10.1.1.2
S 3.0.0.0/8 [1/0] via 10.1.2.2
S 4.0.0.0/8 [1/0] via 192.168.1.2
S 5.0.0.0/8 [1/0] via 192.168.1.6
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, Serial0/0
192.168.1.0/30 is subnetted, 1 subnets
C 192.168.1.0 is directly connected, Serial0/1
S 0.0.0.0/1 is directly connected, Serial0/0
S 128.0.0.0/1 is directly connected, Serial0/0

Since 20.1.1.1 doesn't exist, 1.0.0.0/8 shouldn't be in the RIB as per your post above.
Looks similar to the classful forwarding behavior regarding the default-route and having a major network address.

that because it will recurse to the route below once he takes that out it wont recurse and those routes wont be in the routing table

S 0.0.0.0/1 is directly connected, Serial0/0

when troubleshooting do the recursion process and see if it ends up pointing to an exit interface if it doesnt then it wont be put in the routing table and since these are serial interfaces with default encap it wont hurt to put the exit interface for static routes since there is only 2 end points. You dont want to put the exit interface for multiaccess interfaces or it will arp for every final destination and the next hop router will proxy arp. Thus next hop IP for multiaccess and you only have to arp for the next hop

kryolla wrote: »

that because it will recurse to the route below once he takes that out it wont recurse and those routes wont be in the routing table

S 0.0.0.0/1 is directly connected, Serial0/0

R1(config)#ip route 5.0.0.0 255.0.0.0 192.168.1.6

S 1.0.0.0/8 [1/0] via 20.1.1.1
S 2.0.0.0/8 [1/0] via 10.1.1.2
S 4.0.0.0/8 [1/0] via 192.168.1.2
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, Serial0/0
192.168.1.0/30 is subnetted, 1 subnets
C 192.168.1.0 is directly connected, Serial0/1
S* 0.0.0.0/0 is directly connected, Serial0/0

So why is 5.0.0.0/8 not in the RIB? 192.168.1.6 doesn't exist, why does recursion not occur for this network.

Alright Ed now I have to lab this up see below but on a 3550. This is for the first example

Rack1SW1#
Rack1SW1#sh run | inc class
ip classless
Rack1SW1#sh run | inc zero
ip subnet-zero
Rack1SW1#end
Translating "end"
% Unknown command or computer name, or unable to find computer address
Rack1SW1#sh ip route
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 0.0.0.0 to network 0.0.0.0

10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, FastEthernet0/20
192.168.1.0/30 is subnetted, 1 subnets
C 192.168.1.0 is directly connected, FastEthernet0/19
S* 0.0.0.0/0 is directly connected, FastEthernet0/19
Rack1SW1#deb ip rou
Rack1SW1#deb ip routing ?
<1-199> Access list
<1300-2699> Access list (expanded range)
static IP Static routing
<cr>

Rack1SW1#deb ip routing st
Rack1SW1#deb ip routing static ?
detail IP Static routing detail
route IP Static routing route
summary IP Static routing control summary
time IP Static routing time spent

Rack1SW1#deb ip routing static det
IP static routing detail debugging is on
Rack1SW1#deb ip routing static r
Rack1SW1#deb ip routing static route
% Incomplete command.

Rack1SW1#deb ip routing static route ?
A.B.C.D Destination prefix

Rack1SW1#deb ip routing static route
*Mar 4 22:36:57.976: IP-Static: 0.0.0.0 0.0.0.0 FastEthernet0/19 Path = 1, rou
te table no change, recursive flag clear
*Mar 4 22:36:57.976: IP-Static: 3.0.0.0 255.0.0.0 10.1.2.2 Path = 2 5 6 8, rou
te table deleted, recursive flag set
Rack1SW1#end
Translating "end"
% Unknown command or computer name, or unable to find computer address
Rack1SW1#
*Mar 4 22:37:57.976: IP-Static: 0.0.0.0 0.0.0.0 FastEthernet0/19 Path = 1, rou
te table no change, recursive flag clear
*Mar 4 22:37:57.976: IP-Static: 3.0.0.0 255.0.0.0 10.1.2.2 Path = 2 5 6 8, rou
te table deleted, recursive flag set
Rack1SW1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Rack1SW1(config)#ip route 5.0.0.0 255.0.0.0 192.168.1.6
Rack1SW1(config)#
*Mar 4 22:38:27.304: IP-Static: 5.0.0.0 255.0.0.0 192.168.1.6 Path = 2 5 6 8,
route table deleted, recursive flag set
Rack1SW1(config)#

Here is the second example the 3. network and the 5. network and why it is working

Rack1SW1#sh ip route 192.168.1.6
Routing entry for 128.0.0.0/1, supernet
Known via "static", distance 1, metric 0 (connected)
Routing Descriptor Blocks:
* directly connected, via FastEthernet0/19
Route metric is 0, traffic share count is 1

Rack1SW1#sh ip route 10.1.2.2
Routing entry for 0.0.0.0/1, supernet
Known via "static", distance 1, metric 0 (connected)
Routing Descriptor Blocks:
* directly connected, via FastEthernet0/19
Route metric is 0, traffic share count is 1

Rack1SW1#

It is using these 2 static routes
ip route 0.0.0.0 128.0.0.0 FastEthernet0/19
ip route 128.0.0.0 128.0.0.0 FastEthernet0/19

The 3rd example is the same thing recursive failures
To solve this put a static route for 10.1.2.2 to an exit interface
or ip route 3.0.0.0 255.0.0.0 s0/0

the 4th and final example is not a recursion error its jut not getting installed. It has something to do with the path below.

Rack1SW1#
*Mar 5 00:19:58.028: IP-Static: 2.0.0.0 255.0.0.0 10.1.1.2 Path = 2 3 5 7, rou
te table no change, recursive flag clear
*Mar 5 00:19:58.028: IP-Static: 2.0.0.0 255.128.0.0 2.255.1.1 Path = 2 3 5 6 8
, route table deleted, recursive flag clear
*Mar 5 00:19:58.028: IP-Static: 2.0.0.0 255.240.0.0 2.255.1.1 Path = 2 3 5 6 8
, route table deleted, recursive flag clear
*Mar 5 00:19:58.032: IP-Static: 2.0.0.0 255.128.0.0 192.168.1.2 Path = 2 3 5 7
, route table no change, recursive flag clear

I understand why the routes in the 2nd example are installed, I mainly included it to show that it behaved different than with just the default route configured in the 1st example. What I still don't understand is why 3.0.0.0 and 5.0.0.0 are installed in the 2nd example but not in the 1st. Their next-hop should match the default route but it seems like it is behaving classfully. I tried your debug and it shows this for the first example:

*Mar 1 00:49:25.427: IP-Static: 0.0.0.0 0.0.0.0 Serial0/0 Path = 1, route table no change, recursive flag clear
*Mar 1 00:49:25.427: IP-Static: 1.0.0.0 255.0.0.0 20.1.1.1 Path = 2 3 4 5 7, route table no change, recursive flag clear
*Mar 1 00:49:25.427: IP-Static: 2.0.0.0 255.0.0.0 10.1.1.2 Path = 2 3 5 7, route table no change, recursive flag clear
*Mar 1 00:49:25.427: IP-Static: 3.0.0.0 255.0.0.0 10.1.2.2 Path = 2 5 6 8, route table deleted, recursive flag set
*Mar 1 00:49:25.427: IP-Static: 4.0.0.0 255.0.0.0 192.168.1.2 Path = 2 3 5 7, route table no change, recursive flag clear
*Mar 1 00:49:25.427: IP-Static: 5.0.0.0 255.0.0.0 192.168.1.6 Path = 2 5 6 8, route table deleted, recursive flag set

What do the numbers after Path mean?

Can you explain why you think the 3rd example is a recursive failure? It seems to me that the next hop for 1.0.0.0, 3.0.0.0, and 5.0.0.0 should all match the default route, and the default route's next hop matches 10.1.1.0/24 out Serial0/0, so I don't see what the problem with these routes is.

You figure a static route is pretty simple but this thing is giving me a head ache. For some reason it is not hitting the default route, maybe because there is an entry for the 10. network and 192.168.1 network thus being classfull but ip classless is configured. I also turned it off and still no change. It doesnt matter if you put the default route pointing to a ip address or interface, recursion still fails because it is not hitting the default. But in the 2nd example recursion happens to the 2 static routes. Now why would it recurse for example 2 but not a default route. Ive been trying to research this all day and I still cant explain the last example. I found this from the cisco docs but your last example is different. Maybe someone that is more familair with static routes will jump in. The CCIE lab does not cover static routes.

The following example defines an invalid recursive IPv4 static route. This static route will not be inserted into the IPv4 routing table because it is self-recursive. The next hop of the static route, 192.168.1.0/30, resolves via the first static route 192.168.1.0/24, which is itself a recursive route (that is, it only specifies a next hop). The next hop of the first route, 192.168.1.0/24, resolves via the directly connected route via the serial interface 2/0. Therefore, the first static route would be used to resolve its own next hop.

interface serial 2/0
ip address 10.0.0.1 255.255.255.252
ip route 192.168.1.0 255.255.255.0 10.0.0.2
ip route 192.168.1.0 255.255.255.252 192.168.1.100

In Routing TCP/IP vol1 there is a section on static routes which I will read this weekend and maybe I will have closure on this.

I saw that example in the Cisco docs and I don't understand why those routes wouldn't both be installed. If both routes were in the routing table, a packet to 192.168.1.1 would match 192.168.1.0/30 and a lookup on the next hop (192.168.1.100) would match 192.168.1.0/24. A lookup on the next hop for the /24 (10.0.0.2) would match the directly connected route on S2/0.

I think that whatever is causing these routes to not be installed in the 3rd example, the 4th example, and the cisco doc example are all related. In all of these cases, the next-hop for routes that are not placed in the routing table resolves to a less specific route that includes the route in question. The default route obviously is the least specific route so that would explain why anything matching the default route as it's best match in the 3rd example is not put in the routing table. I've tried out several different route statements and have yet to find an example that goes against this idea. I don't understand why it would work this way though.

for example 3 the 1. network is the same issue as example 4 and the 3 & 4. network is the same issue as example 1. I know how to fix these issues but I cant explain why it is happening.

Rack1SW1(config)#do sh ip route | beg Gateway
Gateway of last resort is 10.1.1.2 to network 0.0.0.0

S 1.0.0.0/8 [1/0] via 20.1.1.1
S 3.0.0.0/8 [1/0] via 10.1.2.2
S 20.0.0.0/8 [1/0] via 10.1.1.2
S 5.0.0.0/8 [1/0] via 192.168.1.6
10.0.0.0/24 is subnetted, 2 subnets
S 10.1.2.0 [1/0] via 10.1.1.2
C 10.1.1.0 is directly connected, FastEthernet0/20
192.168.1.0/30 is subnetted, 2 subnets
C 192.168.1.0 is directly connected, FastEthernet0/19
S 192.168.1.4 [1/0] via 192.168.1.2
S* 0.0.0.0/0 [1/0] via 10.1.1.2

Rack1SW1(config)#do sh run | inc ip route
ip route static adjust-time 30
ip route 0.0.0.0 0.0.0.0 10.1.1.2
ip route 1.0.0.0 255.0.0.0 20.1.1.1
ip route 3.0.0.0 255.0.0.0 10.1.2.2
ip route 5.0.0.0 255.0.0.0 192.168.1.6
ip route 10.1.2.0 255.255.255.0 10.1.1.2
ip route 20.0.0.0 255.0.0.0 10.1.1.2
ip route 192.168.1.4 255.255.255.252 192.168.1.2
Rack1SW1(config)#

kryolla wrote: »

You figure a static route is pretty simple but this thing is giving me a head ache. For some reason it is not hitting the default route, maybe because there is an entry for the 10. network and 192.168.1 network thus being classfull but ip classless is configured.

Glad to see the penny finally dropped and you see the issue.

EdTheLad wrote: »

Glad to see the penny finally dropped and you see the issue.

The issue is still kinda blurry because ip classless is configured buy why isnt it recursing to the default? Also why in example 3 when the default is configured with an ip the 1. network wont recurse to it but it will when the default is configured with an exit interface.

I will ponder this while I drink some of my home brew

Mar 1 01:50:24.699: IP-Static: 1.0.0.0 255.0.0.0 20.1.1.1 Path = 2 3 5 6 8, route table deleted, recursive flag clear
No recursive error but why is it being deleted from RIB

*Mar 1 01:43:43.863: IP-Static: 5.0.0.0 255.0.0.0 192.168.1.6 Path = 2 5 6 8, route table deleted, recursive flag set
recursive error but why isnt it recursing to the default

Yes, i don't know why, i just saw the similarity between classful forwarding behavior, i've no time to research this as i started working on a new cable project last week.I'm up to my eyes in the frequency domain.

Have either of you (or anyone else) found out anything else about either of these issues? I've tried searching around a little bit more but haven't been able to find anything yet to explain them.