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Routing between 3 routers

floofycat
Level 1
Level 1

Hi, i'm new to networking and using Cisco Packet Tracer and I am trying to configure routing across 3 routers. The router I am using is the 2911 Router. Essentially, I have Router A, B and C. Router A is connected to Router B only and Router B is connected to both Router A and Router C. Router C is connected to Router B only. However, I am unable to ping Router C from Router A and vice versa, even with static routing set up. Does anyone know if this can even be done? 

I have attached my compressed PT file and a screenshot of it.

The routers A, B and C refer to Main_Router_SR7A, Main_Router_SR7B and Main_Router_SR7C in the file.

Would appreciate any help please, thanks!

5 Replies 5

Joseph W. Doherty
Hall of Fame
Hall of Fame

"Does anyone know if this can even be done?"

Should be possible.

"Also, I have verified that the static routing has been done properly."

Un-huh.  Well ". . . I'm new to networking . . ." would cause me to suspect, your static routing wasn't done correctly.

Suggest you attach the PT file (as compressed file) so others can example it.

Hi thanks for the reply, i have edited the post and attached my PT File.

Harold Ritter
Cisco Employee
Cisco Employee

Hi @floofycat ,

When you ping from Router A to Router C, the IP address for the interface facing Router B is used as the source address. You need to make sure Router C as a route for that address. 

Main_Router_SR7C
ip route 10.1.1.0 255.255.255.254 10.3.1.2

When you ping from Router C to Router A, the IP address for the interface facing Router B is used as the source address. You need to make sure Router A as a route for that address. 

Main_Router_SR7A
ip route 10.3.1.0 255.255.255.254 10.1.1.2

Regards,

 

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

What @Harold Ritter describes is you're missing some static routes, so your static routing was not done properly, after all.  BTW, no shame in that, often a way to learn (I certainly learned by my [many, many] mistakes - laugh).

Do you understand why those additional static routers are needed?

Also, might you be starting to see the benefit of dynamic routing protocols, even for small/trivial networks?  ; )

Another example (see below) of another ping that doesn't work, is from RtrA, you can not ping RtrC's LAN interfaces either.  However, an alternative is to ping RtrC's LAN interfaces, by using a RtrA LAN interface as the source interface.

Interesting that it works without adding the additional static routes, eh?  Do you understand why?

Also, your static routes could be very much simplified/reduced on Routers A and C.  Any idea how?

Spoiler
What about a default route?

I.e.:

Router#ping
Protocol [ip]:
Target IP address: 10.2.10.1
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.2.10.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

Router#ping
Protocol [ip]:
Target IP address: 10.2.10.1
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 10.0.10.1
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.2.10.1, timeout is 2 seconds:
Packet sent with a source address of 10.0.10.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/0 ms

Martin L
VIP
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