1

I have a Cisco 2960-X switch and a Cisco SG-300 switch. I created VLANs on 2960-X switch (e.g. VLAN 10 with ports 1-5 and VLAN 20 with ports 6-10) and allow DHCP for each VLAN.

Now, laptop 10.10.1.2 and laptop 10.10.2.2 can ping each other successfully.

After this:

  1. I connect SG-300 into a port of VLAN 20. VLAN 20 assigns it an IP address 10.10.2.3 by DHCP.
  2. I connect a third laptop into one port of SG-300 switch. It got an IP address 10.10.2.4 automatically (I did not do any configure on SG-300, a new switch)
  3. laptop 10.10.2.4 can ping 10.10.1.2 successfully.
  4. laptop 10.10.1.2 can ping 10.10.2.3, but cannot ping 10.10.2.4, which is behind SG-300 switch.

Hence, to make 10.10.1.2 ping 10.10.2.4 each other successfully, how to configure SG-300 switch?

enter image description here

  • 1
    Are you sure that laptop 10.10.2.4 can ping 10.10.1.2 successfully (just to be sure it is not a typo)? If it can, then L2 and L3 connectivity appear to be ok and so 10.10.1.2 should also be able to ping 10.10.2.4. If not, then perhaps a host based firewall on 10.10.2.4 is dropping the pings. – hertitu Oct 10 '16 at 9:09
  • yes, 10.10.2.4 can ping 10.10.1.2. maybe firewall, let me check. – Li Dong Oct 10 '16 at 9:37
  • correct, it is the laptop 10.10.2.4 firewall issue. – Li Dong Oct 10 '16 at 9:46
  • I tried another case (background information no change): laptop 10.10.1.2 can only ping SG-300 switch 10.10.2.3 if its IP address is set by DHCP instead of manual address (same address). Do you know what is the reason? – Li Dong Oct 10 '16 at 9:52
3

(copying from the comments as it was confirmed to be the solution)

If 10.10.2.4 can ping 10.10.1.2 successfully then L2 and L3 connectivity appear to be ok and so 10.10.1.2 should also be able to ping 10.10.2.4. If not, then the most likely explanation is that a host-based firewall on 10.10.2.4 is dropping the pings.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.