1

I have created network with 3 routers, 3 switches and 6 computers

Below are configurations,

R1-> serial2/0= 192.168.1.1/30, Fastethernet 0/0= 192.168.1.9/29

R2->serial2/0= 192.168.1.2/30, serial3/0= 192.168.1.5/30, Fastethernet 0/0= 192.168.1.17/28

R3->serial2/0= 192.168.1.6/30 Fastethernet 0/0= 192.168.1.33/28

PC IP's are dhcp

PC1 Ping are below,

Pinging 192.168.1.1 with 32 bytes of data:
Reply from 192.168.1.1: bytes=32 time=2ms TTL=255
Reply from 192.168.1.1: bytes=32 time=0ms TTL=255
Reply from 192.168.1.1: bytes=32 time=0ms TTL=255
Reply from 192.168.1.1: bytes=32 time=0ms TTL=255

Ping statistics for 192.168.1.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 2ms, Average = 0ms

But Ping to next router R2 is not pinging from PC 1

PC>ping 192.168.1.2
Pinging 192.168.1.2 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Ping statistics for 192.168.1.2:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

Please help on this

enter image description here

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  • 2
    Please specify IP's of your PC from what you pingning routers. Also, check that your R2 and R3 know about your PC network, and your PC has default route via R1 (if I get your schema right). It would be better if you will provide simple schematic of your pc/router connections. Oct 12, 2017 at 9:14
  • 2
    Please update your question with a network diagram and the configuration of all routers and switches. Your question just contains the IP addresses and Ping outputs.
    – Hung Tran
    Oct 12, 2017 at 10:09
  • 1
    The router names in your question (R1, R2 and R3) and your network diagram (R0, R1 and R2) do not match. The answers below used the names in your network diagram (R0, R1 and R2 - left to right)
    – Hung Tran
    Oct 12, 2017 at 14:10
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could post and accept your own answer.
    – Ron Maupin
    Jan 3, 2021 at 16:31

3 Answers 3

1

I believe that is because R1 does not have a route for network 192.168.1.8/29 (where you have R0's f0/0 interface, PC0 and PC1). Therefore, R1 does not know where to return the traffic to PC1.

PC1 has the IP 192.168.1.11 with default gateway 192.168.1.9. It can ping 192.168.1.1 because this IP is on R0 and R0 know where to return traffic to PC1 (f0/0 directly connected network).

Simply add the following static route on R1 and try again:

ip route 192.168.1.8 255.255.255.248 192.168.1.1
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  • R0 will also need a route to 192.168.1.17/28 unless it has a default gateway.
    – TDurden
    Oct 12, 2017 at 12:33
  • You always need a return route for ICMP replies.
    – TDurden
    Oct 12, 2017 at 13:27
  • @TDurden Please check his question again. He was pinging 192.168.1.2 from his 192.168.1.11. There is nothing related to 192.168.1.16/28 at the moment.
    – Hung Tran
    Oct 12, 2017 at 13:41
  • @TDurden I just focus on what he needs is to ping 192.168.1.2 from PC1, thus we do not need that route 192.168.1.16/28 for on R0 at the moment.
    – Hung Tran
    Oct 12, 2017 at 13:44
1

R1 likely does not have a route to 192.168.1.9/29 and R0 likely does not have a route back to 192.168.1.17/28.

By default, a router will add connected routes into its routing table. This means that R1 will know how to get to 192.168.1.0/30, 192.168.1.4/30 and 192.168.1.16/28.

The router will not dynamically share or learn its routes with other routers without a dynamic routing protocol such RIP, OSPF, EIGRP or BGP. A router can be configured to statically install routes as well. A common example is a default route or "all zeros" route.

One solution would be to run a dynamic routing protocol across R0 and R1. Another solution would be to manually configure static routes on R0 and R1.

Static Routes

!R0
ip route 192.168.1.16 255.255.255.240 192.168.1.2

!R1
ip route 192.168.1.8 255.255.255.248 192.168.1.1
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  • Your next-hop IP in static routes is not correct! It should be .2 and .1 rather than .17 and .16.
    – Hung Tran
    Oct 12, 2017 at 12:30
  • You are correct, I made a mistake in haste.
    – TDurden
    Oct 12, 2017 at 12:31
0

To ensure communication between three networks .make sure correct and proper routing is in place ..

Router0

Router0(config)#ip route 192.168.1.16 subnet mask 255.255 .240.0 pointing towards gateway 192.168.1.2

Router0(config)#ip route 192.168.1.32 subnetmask 255.255.248.0 pointing towards gateway 192.168.1.2

In Router1

Router1(config)#ip route 192.168.1.255.255.248.0pointing towards gateway 192.168 .1.1

Router1(config)#ip route 192.168.1.32 subnetmask255.255 .240.0 pointing towards gateway 192.168.1.6

In Router2

Router2(config)#ip route 192.168.1.0 255.255.248.0 pointing towards gateway 192.168.1.5

Router2(config)#ip route 192.168.1.16 subnetmask 255.255.240.0 pointing towards gateway 192 .168.1.5

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