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Community Member

unable to access router after changing default route

previously i was able to access 192.80.174.236 as the default route was pointing to the right way.

but we needed to change the default router to point to an IP that is not within our network.

once we did that, we lost connection to the router. currently we are only able to access the router from another router that is "connected" via vlan 50.

but the weird thing is this

GW1#ping 192.80.174.236

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.80.174.236, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

GW1#ping 192.80.174.236 source 192.80.174.6

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.80.174.236, timeout is 2 seconds:

Packet sent with a source address of 192.80.174.6

.....

Success rate is 0 percent (0/5)

--------------------------------

GW1#sh ip int br

Interface                  IP-Address      OK? Method Status                Protocol

GigabitEthernet0/0         unassigned      YES NVRAM  up                    up     

GigabitEthernet0/0.49      unassigned      YES NVRAM  up                    up     

GigabitEthernet0/0.50      192.80.174.233  YES NVRAM  up                    up     

GigabitEthernet0/1         192.80.174.6    YES NVRAM  up                    up     

it seems to indicate that GW1 is dropping the connection here because it is unable to make the link from .6 to .233

any idea what I am missing here?

GW1#sh ip route 192.80.174.236

Routing entry for 192.80.174.236/32

  Known via "static", distance 1, metric 0 (connected)

  Routing Descriptor Blocks:

  * directly connected, via GigabitEthernet0/0.50

      Route metric is 0, traffic share count is 1

1 ACCEPTED SOLUTION

Accepted Solutions
Community Member

unable to access router after changing default route

Sharin Taib wrote:

Hi Mohit,

the info is all on top. there is a switch in between the devices, but it's just configured as trunk and access ports only, to carry the vlan 50


Hi Sharin

I could not see the ouput of sh int g0/0 or g0/1 - the reason i was asking was to understand the subnet mask.

also i could not see the output of " ping 192.80.174.233 source 192.80.174.6". you have showed "ping 192.80.174.236 source 192.80.174.6".

i am quite confident that its a routing issue on the device .236.

i believe you mentioned that you can login to the device by using device in the middle. if you do "sh ip route" you will see that you dont have a route to reach 192.80.174.6.

So either you need a static route or a deafult route to get this issue sorted.

all the best mate!

Mohit

14 REPLIES

unable to access router after changing default route

Hi,

    If you don't have routes back to GW1. it might be the problem. You can check things by using a "traceroute" command. 

HTH,

Toshi

Community Member

unable to access router after changing default route

Hi Toshi,

What do you mean "routes back to GW1"? all trace leads to failure at GW1.

unable to access router after changing default route

Hi,

   It should be a routing problem. As you know, router needs to know how to go. It consults the routing table. It's a good idea to post a brief diagram.

Toshi

Community Member

unable to access router after changing default route

GW1#sh ip route 192.80.174.236

Routing entry for 192.80.174.236/32

  Known via "static", distance 1, metric 0 (connected)

  Routing Descriptor Blocks:

  * directly connected, via GigabitEthernet0/0.50

      Route metric is 0, traffic share count is 1

I know it's a routing problem. What I don't get is why, after the statement above.

unable to access router after changing default route

Hi,

   The other router needs to know how to go 192.80.174.6(or network). Are you trying to use 192.80.174.6 as a source?

HTH,

Toshi

Community Member

unable to access router after changing default route

Sharin Taib wrote:

previously i was able to access 192.80.174.236 as the default route was pointing to the right way.

but we needed to change the default router to point to an IP that is not within our network.

once we did that, we lost connection to the router. currently we are only able to access the router from another router that is "connected" via vlan 50.

but the weird thing is this

GW1#ping 192.80.174.236 source 192.80.174.6

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.80.174.236, timeout is 2 seconds:

Packet sent with a source address of 192.80.174.6

.....

Success rate is 0 percent (0/5)

GW1#sh ip int br

Interface                  IP-Address      OK? Method Status                Protocol

GigabitEthernet0/0         unassigned      YES NVRAM  up                    up     

GigabitEthernet0/0.49      unassigned      YES NVRAM  up                    up     

GigabitEthernet0/0.50      192.80.174.233  YES NVRAM  up                    up     

GigabitEthernet0/1         192.80.174.6    YES NVRAM  up                    up     

it seems to indicate that GW1 is dropping the connection here because it is unable to make the link from .6 to .233

any idea what I am missing here?

GW1#sh ip route 192.80.174.236

Routing entry for 192.80.174.236/32

  Known via "static", distance 1, metric 0 (connected)

  Routing Descriptor Blocks:

  * directly connected, via GigabitEthernet0/0.50

      Route metric is 0, traffic share count is 1

Hi Sharin,

I dont think it is a routing issue at GW1. to confirm that, ping 192.80.174.233 source 192.80.174.6. if that works, then it means routing is fine at this side.

If that is replying normal, then you need to check the other side.

Let me know how you go?

can you also send me the " sh ip route "

Cheers,

Mohit

unable to access router after changing default route

To add....sometimes with routing you have to check both routes, the route TO the destination and BACK.

unable to access router after changing default route

Jimmy,

    That's what I'm trying to say. 

5-Point for you.

Toshi

Community Member

unable to access router after changing default route

Sharin,

if you can let me know the results of the ping test i mentioned above, that would be quite helpful to troubleshoot.

also, can you advise me the output of sh int g0/0.

thanks,

Mohit

Community Member

unable to access router after changing default route

jimmysands73 wrote:

To add....sometimes with routing you have to check both routes, the route TO the destination and BACK.

Exactly, looking at the snap shot Sharin sent from the GW1, it clearly states it knows about the other network simply for the reason it is directly connected.

                    GW1#sh ip route 192.80.174.236

                    Routing entry for 192.80.174.236/32

                      Known via "static", distance 1, metric 0 (connected)

                      Routing Descriptor Blocks:

                      * directly connected, via GigabitEthernet0/0.50

Community Member

unable to access router after changing default route

Mohit Chauhan wrote:


Exactly, looking at the snap shot Sharin sent from the GW1, it clearly states it knows about the other network simply for the reason it is directly connected.

                    GW1#sh ip route 192.80.174.236

                    Routing entry for 192.80.174.236/32

                      Known via "static", distance 1, metric 0 (connected)

                      Routing Descriptor Blocks:

                      * directly connected, via GigabitEthernet0/0.50

Thanks Mohit.

That's the reason for the confusion. Why GW1 shows it as connected and static, but unable to connect if the source is via 174.6

Community Member

unable to access router after changing default route

Sharin Taib wrote:

Mohit Chauhan wrote:


Exactly, looking at the snap shot Sharin sent from the GW1, it clearly states it knows about the other network simply for the reason it is directly connected.

                    GW1#sh ip route 192.80.174.236

                    Routing entry for 192.80.174.236/32

                      Known via "static", distance 1, metric 0 (connected)

                      Routing Descriptor Blocks:

                      * directly connected, via GigabitEthernet0/0.50

Thanks Mohit.

That's the reason for the confusion. Why GW1 shows it as connected and static, but unable to connect if the source is via 174.6

Hi Sharin

it is quite simple, you should be able to ping the 192.80.174.233 from 192.80.174.6.

However when you are trying to ping .236, the ping should be directed to the correct direction by GW1 off via .233. But the device who has this address .236 may not know where is .6 network. thats the reason it cannot reply back and you dont see ping replies coming back.

just send me the requested outputs:

sh ip route from GW1

ping 192.80.174.233 source 192.80.174.6

sh int g0/0

sh int g0/1

A question there- do you know this .236 is a device directly connected to GW1 or there are some more routing devices in the path?

looking forward to your reply.

Cheers,

Mohit

Community Member

unable to access router after changing default route

Hi Mohit,

the info is all on top. there is a switch in between the devices, but it's just configured as trunk and access ports only, to carry the vlan 50

Community Member

unable to access router after changing default route

Sharin Taib wrote:

Hi Mohit,

the info is all on top. there is a switch in between the devices, but it's just configured as trunk and access ports only, to carry the vlan 50


Hi Sharin

I could not see the ouput of sh int g0/0 or g0/1 - the reason i was asking was to understand the subnet mask.

also i could not see the output of " ping 192.80.174.233 source 192.80.174.6". you have showed "ping 192.80.174.236 source 192.80.174.6".

i am quite confident that its a routing issue on the device .236.

i believe you mentioned that you can login to the device by using device in the middle. if you do "sh ip route" you will see that you dont have a route to reach 192.80.174.6.

So either you need a static route or a deafult route to get this issue sorted.

all the best mate!

Mohit

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