06-30-2020 08:41 AM
Bear with me as I am a beginner and might not be using correct terminology. I have a new issue as of this week where I cannot communicate with another subnet from 1 of my 10 workstations. Basically we have 2 networks, A (10.13.153) and B(10.13.154) connected by a 3850 router. There are 10 workstations in each network. Every workstation in A can communicate with every workstation in B. All of the sudden one 1 of my workstations in network A cannot communicate with network B. Everything else is working fine. Every other station can communicate with every other station. The workstation in question can communicate with the other 9 workstations in network A but cannot even ping the router. If I change the IP address of this 1 station, everything starts to work fine. If I change it back to the original IP, it stops working again. No changes have been made at all. I feel like it has to be something in the router but have no idea what to look for. There are no IP specific ACL’s configured in the router. Any direction is appreciated.
06-30-2020 08:50 AM
Can you share the network parameters configured on the workstation with problems?
Assigned IP
Netmask
Gateway
You could also share the parameters configured in the router's interface.
Regards
06-30-2020 09:37 AM
In addition to the items requested by @luis_cordova would you also provide these:
- the mac address of the PC that has the problem. (probably the output of ipconfig would be the easy way but you could also get it by show mac address table on the 3850 and look for the mac address on the port that connects to that PC).
- the IP address on the PC when it has the problem.
- the IP address on the PC when you change the address and it works.
- the output of show arp on the 3850.
06-30-2020 10:48 AM
Mac Address: 00:0A:F7:82:73:AA
IP w/Problem: 10.13.153.54
IP wo/Problem: 10.13.153.59
ARP Output:
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.13.152.1 - 0000.0c07.ace7 ARPA Vlan301
Internet 10.13.152.3 - 00b1.e33c.44e2 ARPA Vlan301
Internet 10.13.152.4 145 00d6.fe51.6f62 ARPA Vlan301
Internet 10.13.152.111 243 509a.4c9f.e24c ARPA Vlan301
Internet 10.13.152.113 1 509a.4c76.66fd ARPA Vlan301
Internet 10.13.152.115 0 b026.28c4.14ae ARPA Vlan301
Internet 10.13.152.116 1 6c2b.59ae.2968 ARPA Vlan301
Internet 10.13.152.254 5 fc5b.392d.b788 ARPA Vlan301
Internet 10.13.153.51 0 246e.968b.1728 ARPA GigabitEthernet1/0/2
Internet 10.13.153.52 0 246e.968b.3a4c ARPA GigabitEthernet1/0/2
Internet 10.13.153.53 0 246e.968b.17d0 ARPA GigabitEthernet1/0/2
Internet 10.13.153.54 0 000a.f782.73aa ARPA GigabitEthernet1/0/2
Internet 10.13.153.56 0 246e.968b.3ad4 ARPA GigabitEthernet1/0/2
Internet 10.13.153.57 0 246e.968a.4630 ARPA GigabitEthernet1/0/2
Internet 10.13.153.60 0 246e.9678.f730 ARPA GigabitEthernet1/0/2
Internet 10.13.153.71 24 847b.ebf0.ee5a ARPA GigabitEthernet1/0/2
Internet 10.13.153.72 123 847b.ebf0.ee69 ARPA GigabitEthernet1/0/2
Internet 10.13.153.73 2 847b.ebf0.f0b0 ARPA GigabitEthernet1/0/2
Internet 10.13.153.75 166 847b.ebf0.edb0 ARPA GigabitEthernet1/0/2
Internet 10.13.153.100 0 509a.4c69.b54b ARPA GigabitEthernet1/0/2
Internet 10.13.153.101 0 d094.6605.601d ARPA GigabitEthernet1/0/2
Internet 10.13.153.102 0 d094.6605.5e2e ARPA GigabitEthernet1/0/2
Internet 10.13.153.103 76 6c2b.5986.011e ARPA GigabitEthernet1/0/2
Internet 10.13.153.239 170 f8b7.e262.ebe9 ARPA GigabitEthernet1/0/2
Internet 10.13.153.241 80 b4a8.b9fe.5542 ARPA GigabitEthernet1/0/2
Internet 10.13.153.242 167 b4a8.b9fe.7cc2 ARPA GigabitEthernet1/0/2
Internet 10.13.153.243 3 6cdd.3035.83c2 ARPA GigabitEthernet1/0/2
Internet 10.13.153.244 2 6cdd.3035.3042 ARPA GigabitEthernet1/0/2
Internet 10.13.153.252 - 00b1.e33c.44d6 ARPA GigabitEthernet1/0/2
Internet 10.13.153.254 - 0000.0c07.ac65 ARPA GigabitEthernet1/0/2
Internet 10.13.154.51 0 246e.9678.fe4c ARPA GigabitEthernet1/0/3
Internet 10.13.154.52 0 246e.9678.ebbc ARPA GigabitEthernet1/0/3
Internet 10.13.154.53 0 246e.9678.f640 ARPA GigabitEthernet1/0/3
Internet 10.13.154.54 0 000a.f782.73b2 ARPA GigabitEthernet1/0/3
Internet 10.13.154.55 0 246e.968a.4674 ARPA GigabitEthernet1/0/3
Internet 10.13.154.56 0 246e.968b.4014 ARPA GigabitEthernet1/0/3
Internet 10.13.154.60 0 246e.968a.43ec ARPA GigabitEthernet1/0/3
Internet 10.13.154.71 156 847b.ebf0.ed7b ARPA GigabitEthernet1/0/3
Internet 10.13.154.72 257 847b.ebf0.f0b9 ARPA GigabitEthernet1/0/3
Internet 10.13.154.74 171 847b.ebf0.f082 ARPA GigabitEthernet1/0/3
Internet 10.13.154.75 103 0080.64f5.debe ARPA GigabitEthernet1/0/3
Internet 10.13.154.100 0 509a.4c69.b4b3 ARPA GigabitEthernet1/0/3
Internet 10.13.154.101 0 d094.6605.5d1b ARPA GigabitEthernet1/0/3
Internet 10.13.154.102 0 d094.6605.635d ARPA GigabitEthernet1/0/3
Internet 10.13.154.103 0 6c2b.5986.03c6 ARPA GigabitEthernet1/0/3
Internet 10.13.154.150 8 9c93.4e65.9465 ARPA GigabitEthernet1/0/3
Internet 10.13.154.239 64 f8b7.e262.ea7d ARPA GigabitEthernet1/0/3
Internet 10.13.154.240 63 ec1d.8b19.577d ARPA GigabitEthernet1/0/3
Internet 10.13.154.241 71 b4a8.b9fe.78c2 ARPA GigabitEthernet1/0/3
Internet 10.13.154.242 51 b4a8.b9fe.7c42 ARPA GigabitEthernet1/0/3
Internet 10.13.154.243 4 6cdd.3035.61c2 ARPA GigabitEthernet1/0/3
Internet 10.13.154.244 14 6cdd.3034.d742 ARPA GigabitEthernet1/0/3
Internet 10.13.154.252 - 00b1.e33c.44d8 ARPA GigabitEthernet1/0/3
Internet 10.13.154.253 7 00d6.fe51.6f58 ARPA GigabitEthernet1/0/3
Internet 10.13.154.254 - 0000.0c07.ac66 ARPA GigabitEthernet1/0/3
06-30-2020 01:59 PM
Thank you for the additional information. Can you help us understand the network a bit better. When you described 2 networks connected by 3850 I assumed that the devices in the networks were connected to the 3850. But the arp output shows that every device in the 10.13.153 network is connected through Gig1/0/2. So what is connected to Gig1/0/2? I am also interested in the fact that the interface is configured with HSRP. Does this mean that there is a second layer 3 device routing for this network? Can you tell us more about this other device? Also can you tell us whether the PCs are learning their IP via DHCP or are they manually configured?
You tell us that when configured with .54 the PC can not ping the router. Is the PC attempting to ping the interface address or to ping the HSRP virtual address?
Also would you perform this test:
- configure the PC with .54
- attempt to ping the router
- attempt to ping the other network
- do arp -a and post the output
- configure the PC with .59
- attempt to ping the router
- attempt to ping the other network
- do arp -a and post the output
06-30-2020 02:48 PM
You are correct. There is a 2nd router but it is identical. Every switch and router in the network is redundant and there are 2 nic cards on every station. This is a process network in an industrical facility. The network is set up in what Honeywell calls FTE, or fault taulerant ethernet. Basically you can lose any 1 device/connection and still maintain communication. All of the stations in each network are connected to a layer 2 switch and the layer 2 switch is connected to Gig0/1/2. FYI, I can ping the layer 2 switch.
When I have been attempting to ping the router is has been with the 10.13.153.254 address which is what we have configured for the DG. No DHCP. Everything is static.
07-01-2020 02:43 PM
Thanks for the additional information. I suggested some steps for additional testing. I would add to them a suggestion that when you attempt to ping the router that you try both the HSRP virtual address (254) but also try the interface IP address.
06-30-2020 10:20 AM
Assigned IP: 10.13.153.54
Netmask: 255.255.255.0
DG: 10.13.153.254
Switch Interface:
interface GigabitEthernet1/0/2
description TO COBRBBSW1Y
no switchport
ip address 10.13.153.252 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
ip pim dense-mode
standby 101 ip 10.13.153.254
standby 101 timers 2 6
standby 101 priority 105
standby 101 preempt delay minimum 90
standby 101 track 2 decrement 10
standby 101 track 4 decrement 10
!
interface GigabitEthernet1/0/3
description TO LIBRBBSW1Y
no switchport
ip address 10.13.154.252 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
ip pim dense-mode
standby 102 ip 10.13.154.254
standby 102 timers 2 6
standby 102 priority 105
standby 102 preempt delay minimum 90
standby 102 track 1 decrement 10
standby 102 track 4 decrement 10
!
When I change IP to 10.13.153.59 then I can ping to router
07-01-2020 01:29 AM - edited 07-01-2020 03:46 AM
Hello
@DerekRhodes64553 wrote:
If I change the IP address of this 1 station, everything starts to work fine. If I change it back to the original IP, it stops working again. No changes have been made at all.
Is it possible you have a duplicate ip address for this host?
If it a windows host, you can reset its ip stack and winsock api and reboot it, to see if its clears your issue.
windows host pc
netsh interface ipv4 reset reset.log
netsh winsock reset reset.log
shutdown -r -f -t 10
07-02-2020 08:12 AM
So it's working again but I didn't really do anything. I changed the IP to .59 for some testing and left it there for a day. When I put it back to .54 it is now working all of the sudden. Any ideas
07-02-2020 10:40 AM
Interesting that it is now working again. From my perspective my first guess at the problem would be that some other device was using the .54 address. I also wonder about the possibility that something in the FTE environment was out of sync and caused it. But we do not know enough about that environment to be able to help.
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