No Ping Between 2 Hosts

NiceRoute

Hi,

I had a problem the other day, I couldn't ping from host A (10.44.33.2/24) to host B(10.44.33.55/24). It seemed to be a badic connectivity problem, however there was something pretty strange:

*Pay attention both hosts are on the same LAN.

First, I could ping host B from any other device on the network and host B could ping any other device. So there was only no ping from host A to B and visa versa.

Second, no Firewalls or Access Lists are applied anywhere on the network.

I tried to clear ARP tables but it didn't work.

Does anybody have an idea?

Thanks in advance

Priston

Is there a gateway? Can the gateway ping both hosts? Do both host show in the arp table on the gateway?

GDaines

I'm assuming these are two hosts connected to the same switch? You haven't stated whether host A can ping anything or be pinged by anything else, simply that hosts A and B can't ping each other but that host B can ping everything else and be pinged by everything else, so it is assumed that host A can't see anything or be seen by anything. Are you using DHCP or statically assigned IP addresses?

First make sure that the port in which host A is connected is not "shutdown" (by default switch ports are enabled, router ports disabled). Next make sure they're both in the same VLAN. On the PC if you've statically assigned the IP addresses make sure you've not made a mistake when setting the default gateway.

If there's a router in between (Host A -> SW1 -> R1 -> SW2 -> Host then it's a whole different scenario, so more details are required as to the network layout.

Simrid

Do the routers have routes to get to one another? They will need to know how to return the ping request.

NiceRoute

Yes There's a gateway and it can ping both hosts, and both of them can be seen on the ARP table.

NiceRoute

Simrid wrote: »

Do the routers have routes to get to one another? They will need to know how to return the ping request.

Both of them are on the same LAN.

NiceRoute

Priston wrote: »

Is there a gateway? Can the gateway ping both hosts? Do both host show in the arp table on the gateway?

Yes There's a gateway and it can ping both hosts, and both of them can be seen on the ARP table.

Nightflier101BL

Can Host A reach anything else in the same subnet?

NiceRoute

GDaines wrote: »

I'm assuming these are two hosts connected to the same switch? You haven't stated whether host A can ping anything or be pinged by anything else, simply that hosts A and B can't ping each other but that host B can ping everything else and be pinged by everything else, so it is assumed that host A can't see anything or be seen by anything. Are you using DHCP or statically assigned IP addresses?

First make sure that the port in which host A is connected is not "shutdown" (by default switch ports are enabled, router ports disabled). Next make sure they're both in the same VLAN. On the PC if you've statically assigned the IP addresses make sure you've not made a mistake when setting the default gateway.

If there's a router in between (Host A -> SW1 -> R1 -> SW2 -> Host then it's a whole different scenario, so more details are required as to the network layout.

1. Both host A and B can ping and be pinged to and from anything else on the network.

2. No DHCP used, only static assignment of IP.

3. Network settings are correct, same gateway and same subnet, also note that I've stated that both of the hosts are on the same LAN.

4. There are no VLANs, only VLAN 1 is used throughout the whole network (Yeah I Know it's stupid and non-secure).

NiceRoute

Nightflier101BL wrote: »

Can Host A reach anything else in the same subnet?

Yeah....

Nightflier101BL

Are both devices plugged into the same switch? Just one switch?

NiceRoute

Nightflier101BL wrote: »

Are both devices plugged into the same switch? Just one switch?

They're plugged into different switches

Nightflier101BL

Can you post a diagram of the complete topology, showing the layout of the various devices and where they're plug in?

Post your configs for the switches.

TechGuru80

What OS? Let me guess...Windows. If so check Windows Firewall rules and since it's a lab just add an allow rule for ICMP.

james43026

Nightflier101BL wrote: »

Can you post a diagram of the complete topology, showing the layout of the various devices and where they're plug in?

Post your configs for the switches.

Ditto on this. Gonna need full running config from both switches involved. As well as the running config for your router. Also do a traceroute from the problem device and post that as well.

GDaines

Nightflier101BL wrote: »

Can you post a diagram of the complete topology, showing the layout of the various devices and where they're plug in?

As I eluded to in my first response (post #3), if you don't provide a network diagram or clear description of what plugs into what and the configuration of each interface in that chain then no-one is going to be able to give a useful answer as to where the problem might lie as we're all just blindly guessing.

If you have no means to draw a diagram check these out (I have no idea if any are any good or not, I struggle along with Visio).