Gateway fails to connect with router but router can ping gateway.

[sadqazi]

Hello All,

I am setting up a Cisco 2911 router and came across a problem with the gateway connection.

My VM can access the gateway (192.168.1.1) but the gateway fails to ping my router (192.168.1.2). The message I get is 

VM-xxx>ping 192.168.1.2
PING 192.168.1.2 (192.168.1.2) 56(84) bytes of data.
From 192.168.1.1 icmp_seq=2 Destination Host Unreachable
From 192.168.1.1 icmp_seq=3 Destination Host Unreachable
From 192.168.1.1 icmp_seq=4 Destination Host Unreachable
From 192.168.1.1 icmp_seq=6 Destination Host Unreachable
From 192.168.1.1 icmp_seq=7 Destination Host Unreachable
From 192.168.1.1 icmp_seq=8 Destination Host Unreachable
--- 192.168.1.2 ping statistics ---
10 packets transmitted, 0 received, +6 errors, 100% packet loss, time 8999ms
, pipe 3

The router itself is able to ping the gateway, as shown below:

Router#ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms

Any ideas what is going on? and how to fix it?

Thank you,

Sadaf.

[Traian Bratescu]

Hi,

Any firewall/ACL?

Traian

[sadqazi]

No Firewalls. This is a lab network and the router and the Gateway are on the same network.

When I do arp -a, this is what I get:

VM-xxxx> arp -a
ts1 (192.168.1.2) at <incomplete> on eth1
? (172.19.165.1) at 00:00:0C:07:AC:0B [ether] on eth0

But if I do arp -a on another 2911 that is connected to the gateway, I get:

? (172.19.157.1) at 00:00:0C:07:AC:0B [ether] on eth0
ts1 (192.168.1.2) at 00:B0:64:FD:51:04 [ether] on eth1
? (172.19.157.54) at B8:27:EB:36:35:EE [ether] on eth0

Now the configuration for the ts1 that is not connecting is the exact same as the second ts1 which has a working connection with gateway. The mac address is specified for both as:

interface GigabitEthernet0/0
 mac-address 00b0.64fd.5104
 ip address 192.168.1.2 255.255.255.0
 no ip route-cache
 duplex auto
 speed auto
 no keepalive

Thank you,

Sadaf.

[Traian Bratescu]

Hi,

It seems very awkward to ping one direction and than have an incomplete arp resolution; could you check if the mac address on the first reply is as expected?

Check also for duplicate MAC address; additionally can you send a simple deign - thant wayyou can also check The IP/MAC addresses of each device? I don't quite understand who has which ip address.

Traian

[sadqazi]

I haven't seen duplicate MAC addresses but the interface0/0 has two mac addresses assigned.

Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  1.1.1.1                 -            f4cf.e268.0dd8  ARPA   GigabitEthernet1/0
Internet  192.168.1.1         6           0050.56bf.22dc  ARPA   GigabitEthernet0/0
Internet  192.168.1.2         -            00b0.64fd.5104  ARPA   GigabitEthernet0/0

But this shouldn't be an issue as I have the same setting for the 2911s that have a working connection.

I realized just now that gi0/0 is also assigned 192.168.1.1 and the failed ping is from 192.168.1.1 to 192.168.1.2 !

VM-xxx>ping 192.168.1.2
PING 192.168.1.2 (192.168.1.2) 56(84) bytes of data.
From 192.168.1.1 icmp_seq=2 Destination Host Unreachable

???

This just keeps getting more and more strange.

-Sadaf.

[Madhukrishnan Gopinathan Nair]

Dear Sadaf,

Sorry to say I am getting confused. First of all what do you mean by gateway?

Also can you draw a simple diagram showing what is what?

Thanks,

Madhu

[sadqazi]

I am very sorry. You got confused because my question was all confusing. In fact I was not clear about my topology which is at terrible thing. As it turns out, there is no gateway and the router interface 0/0 is assigned two ip addresses and two mac addresses. One is the 192.168.1.1 and the other is 192.168.1.2 and the VM is able to ping the .1 but the ping to .2 fails and returns the message "Destination host unreachable". My apologies for being so clueless and asking questions without setting the facts straight.

I have attached the diagram and hopefully it will clear some confusions.

-Sadaf.

[Madhukrishnan Gopinathan Nair]

Can you share the config for interface 0/0

[sadqazi]

Sure. 

interface GigabitEthernet0/0
 mac-address 00b0.64fd.5104
 ip address 192.168.1.2 255.255.255.0
 no ip route-cache
 duplex auto
 speed auto
 no keepalive

Thank you,

Sadaf

[Madhukrishnan Gopinathan Nair]

there is no gateway and the router interface 0/0 is assigned two ip addresses and two mac addresses. One is the 192.168.1.1 and the other is 192.168.1.2 

--  where is 192.168.1.1 configured?

Madhu

[sadqazi]

Ummm..... I don't know. I only did the configuration for 192.168.1.2 but somehow it has two ip addresses as shown by the show arp command.

ts1#show arp

Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  1.1.1.1                 -            f4cf.e268.0dd8  ARPA   GigabitEthernet1/0
Internet  192.168.1.1         6           0050.56bf.22dc  ARPA   GigabitEthernet0/0
Internet  192.168.1.2         -            00b0.64fd.5104  ARPA   GigabitEthernet0/0

I have no idea where this other 192.168.1.1 is configured. 

I think that for some reason, the VM is unable to resolve the mac address of Gi0/0 port with ip address 192.168.1.2 because 

VM-xxxx> arp -a

gives 
ts1 (192.168.1.2) at <incomplete> on eth1
 

[Madhukrishnan Gopinathan Nair]

What is default gateway for the VM, is it 192.168.1.1?

Also what is VM ip adress.

share ipconfig from VM.

Please send me the output of 

sh cdp neighbors Gi0/0  from ts1.

Also it is expected to see 2 ip address Gi0/0, it is showing that it can resolve the arp for 192.168.1.2

[saif musa]

Did you apply any type of routing protocols inside your router ??  If not, apply static route inside your router which will be like this..

Config()#ip route 0.0.0.0 0.0.0.0 192.168.1.1

                   wr

                    exit

[sadqazi]

I did apply this static route but it didn't resolve the issue. Even after this static route was in the router's config, the ping still didn't work

[saif musa]

Could you upload router running-config please ?? it will helps a lot.