Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Community Member

Static Routing - problem with ping

Good morning,

I'm new to networks and I've created this topology [attachment].
On R1 "ping 4.4.4.4" / "ping 4.4.4.4 source 1.1.1.1" doesn't work.
Any tip why? What am I missing?


R1
ip route 4.4.4.4 255.255.255.255 e0/0
ip route 4.4.4.4 255.255.255.255 s1/0

R2
ip route 1.1.1.1 255.255.255.255 e0/0
ip route 4.4.4.4 255.255.255.255 e0/1

R3
ip route 1.1.1.1 255.255.255.255 s1/0 13.13.13.1
ip route 4.4.4.4 255.255.255.255 e0/0 34.34.34.4

R4
ip route 1.1.1.1 255.255.255.255 e0/1
ip route 1.1.1.1 255.255.255.255 e0/0

---

R1
e0/0 12.12.12.1 up/up
s1/0 13.13.13.1 up/up
loop1 1.1.1.1 up/up

R2
e0/0 12.12.12.2 up/up
e0/1 24.24.24.2 up/up
loop1 2.2.2.2 up/up

R3
e0/0 34.34.34.3 up/up
s1/0 13.13.13.3 up/up
loop1 3.3.3.3 up/up

R4
e0/0 34.34.34.4 up/up
e0/1 24.24.24.4 up/up
loop1 4.4.4.4 up/up

1 ACCEPTED SOLUTION

Accepted Solutions
VIP Purple

Hi

Hi

I think the other members have provided very good explanations and how to fix the problem, well I would like to provide my point of view:

In order to reach the IP 4.4.4.4 from R1 you have 2 path, through R2 or R3, static route is the most easy way for routing but it is complex to manage when you have a large network.

Now if you want to reach the R4's IP through R4, you should have the following configured:

R1
ip route 4.4.4.4 255.255.255.255 12.12.12.2


R2
ip route 1.1.1.1 255.255.255.255 12.12.12.1
ip route 4.4.4.4 255.255.255.255 24.24.24.4

R4
ip route 1.1.1.1 255.255.255.255 24.24.24.2

The ping is reciprocal in few words it requires communication in both ways so source and destination must know how to reach each other. 

Now if you want to have redundancy you need to implement floating static routes. 

R1
ip route 4.4.4.4 255.255.255.255 12.12.12.2
ip route 4.4.4.4 255.255.255.255 13.13.13.3  


R2
ip route 1.1.1.1 255.255.255.255 12.12.12.1
ip route 4.4.4.4 255.255.255.255 24.24.24.4

R3
ip route 1.1.1.1 255.255.255.255 13.13.13.1
ip route 4.4.4.4 255.255.255.255 34.34.34.4

R4
ip route 1.1.1.1 255.255.255.255 34.34.34.3  2

By default the administrative distance for static routes is 1, if we talk about administrative distance, the lowest will always preferred, now if you want to have a back up path you can point to other next hop with higher administrative distance than 1, in my example I set up 2 for the path through R3, so if the link between R1 and R2 is down it will go through R3. Now for this scheme I recommend use a dynamic routing protocol like RIPv2, EIGRP, OSPF, etc. 

Then sintaxis of a static route is:

ip route <network segment to be known> <subnet mask> <next hop router IP or the local interface> ; I always prefer use the next hop router IP 'the neighbor'

Hope it is useful.

:-)

11 REPLIES
VIP Red

check your routes back , so

check your routes back , so on r4 do a sh ip route 1.1.1.1 and also on R3, check if all routers now all routes

Please rate if helpful

Please remember to rate useful posts, by clicking on the stars below.

Hall of Fame Super Gold

You have given us minimal

You have given us minimal information to work with. I do not see any obvious issues in the partial details provided so far that would cause this problem. Can you provide more complete router configs that might help us to identify the issue? It might also be helpful if you would post the output of show ip rout from each of the routers.

I will make one comment based on what is provided so far. The config on R3 is different from the other routers in that it specifies both the outbound interface and the next hop address while the other routers specify only the outbound interface. This can be problematic, especially when the outbound interface is Ethernet. Among other things this approach requires that proxy arp be enabled on the neighbor router. You might try configuring both the outbound interface and the next hop on the other 3 routers and see if the behavior changes.

HTH

Rick

Community Member

thank you for such a fast

thank you for such a fast responds

rburts  as I mentioned I'm a new one... I don't really know if there's a better option here than pasting all the configs in a separate files

minkdennis  I don't think it's about back routes, in simulation mode Packet Tracer shows problem with ICMP (ARP and CDP are fine)

R4#sh ip route 1.1.1.1
Routing entry for 1.1.1.1/32
  Known via "static", distance 1, metric 0 (connected)
  Routing Descriptor Blocks:
    directly connected, via Ethernet0/1
      Route metric is 0, traffic share count is 1
  * directly connected, via Ethernet0/0
      Route metric is 0, traffic share count is 1

R3#sh ip route 1.1.1.1
Routing entry for 1.1.1.1/32
  Known via "static", distance 1, metric 0
  Routing Descriptor Blocks:
  * 13.13.13.1, via Serial1/0
      Route metric is 0, traffic share count is 1

VIP Purple

Hi

Hi

I think the other members have provided very good explanations and how to fix the problem, well I would like to provide my point of view:

In order to reach the IP 4.4.4.4 from R1 you have 2 path, through R2 or R3, static route is the most easy way for routing but it is complex to manage when you have a large network.

Now if you want to reach the R4's IP through R4, you should have the following configured:

R1
ip route 4.4.4.4 255.255.255.255 12.12.12.2


R2
ip route 1.1.1.1 255.255.255.255 12.12.12.1
ip route 4.4.4.4 255.255.255.255 24.24.24.4

R4
ip route 1.1.1.1 255.255.255.255 24.24.24.2

The ping is reciprocal in few words it requires communication in both ways so source and destination must know how to reach each other. 

Now if you want to have redundancy you need to implement floating static routes. 

R1
ip route 4.4.4.4 255.255.255.255 12.12.12.2
ip route 4.4.4.4 255.255.255.255 13.13.13.3  


R2
ip route 1.1.1.1 255.255.255.255 12.12.12.1
ip route 4.4.4.4 255.255.255.255 24.24.24.4

R3
ip route 1.1.1.1 255.255.255.255 13.13.13.1
ip route 4.4.4.4 255.255.255.255 34.34.34.4

R4
ip route 1.1.1.1 255.255.255.255 34.34.34.3  2

By default the administrative distance for static routes is 1, if we talk about administrative distance, the lowest will always preferred, now if you want to have a back up path you can point to other next hop with higher administrative distance than 1, in my example I set up 2 for the path through R3, so if the link between R1 and R2 is down it will go through R3. Now for this scheme I recommend use a dynamic routing protocol like RIPv2, EIGRP, OSPF, etc. 

Then sintaxis of a static route is:

ip route <network segment to be known> <subnet mask> <next hop router IP or the local interface> ; I always prefer use the next hop router IP 'the neighbor'

Hope it is useful.

:-)

Community Member

thank U @Julio Moisa & thanks

thank you eduardomoi & thanks again to other guys

now it's working, will do step by step troubleshooting
will try with 1) next hop 2) exit-if 3) next hop & exit-if

I thought if I won't set AD (it's gonna be equal) then
ping will go through R2 or through R3 ("randomly")

VIP Purple

Well if you have 2 or more

Hi

You are welcome  :-)

Well if you have 2 or more static routes with the same destination and the same administrative distance but with different next hops, it will create load balance and it could create asymmetric traffic. 

Router(config)#ip route 4.4.4.4 255.255.255.255 12.12.12.2 ?
<1-255> Distance metric for this route

Community Member

"it will create load balance

"it will create load balance and it could create asymmetric traffic"
& in my example it won't allow ping between 1.1.1.1 and 4.4.4.4

VIP Purple

Try using the next hop IP

Try using the next hop IP instead the interfaces only. Remember you also need to create an entry for the point to point networks, Example:

R1
ip route 4.4.4.4 255.255.255.255 12.12.12.2
ip route 24.24.24.0 255.255.255.0 12.12.12.2 name POINT-TO-POINT-R2-and-R4


R2
ip route 1.1.1.1 255.255.255.255 12.12.12.1
ip route 4.4.4.4 255.255.255.255 24.24.24.4

R4
ip route 1.1.1.1 255.255.255.255 24.24.24.2
ip route 12.12.12.0 255.255.255.0 24.24.24.2 name POINT-TO-POINT-R1-and-R2

Remember the routers know about the connected networks but not the networks of the other routers, so R1 should knows the network between R2 and R4 and R4 should knows about the network between R1 and R2. The same situation for the other path. The otherwise the packet will not able to go back or reach the destination. 

:-)

Community Member

Thank you for detailed and

Thank you for detailed and helpful comments! :)

Community Member

I just wanted to give you

I just wanted to give you some additional information: I was using eve 2.0.3-60 and Packet Tracer. In Packet Tracer it was all fine (I tried Simulation Mode after), but I had issues with eve (Emulated Virtual Environment). What I had to do was to set AD values for static routes, these values could be the same (!), I could even remove them after (set to default = 1 for statics). But if I didn't do it then ping from 1.1.1.1 to 4.4.4.4 didn't went through. My point is: keep in mind that software when you learn might be a bit bugged.

Once again thanks to all three guys :)

Hall of Fame Super Gold

Thank you for providing the

Thank you for providing the additional information, especially that this was done with emulation software. If done with actual hardware routers the administrative distance would not have been required. You make a very good point about being very careful about using software to emulate network devices. (+5 for you)

HTH

Rick

321
Views
20
Helpful
11
Replies
CreatePlease to create content