0

I have a router that I can't manage (it is an ISP thing). It is directly connected to a T2600G-18TS (let's call it X) switch. The X switch has a static IP assigned from the routers IP range. I have another T2600G-18TS (let's call it Y) switch that is connected to a X switch. It also has a static IP assigned from the routers IP range. Next I would like to have 3 VLANs so I followed this tutorial about DHCP relay click. The only change is 192.168.0.1 is the ISP's router IP and X's IP address is 192.168.0.9. Everything seems to be working, different ports assigned to specific VLANs get proper IPs etc. The only problem I have and can't resolve on my own is Internet access. When I connect directly to the X switch my computer gets IP address from the routers IP range and I can access the Internet. However, whichever VLAN I connect (using the Y switch) I get proper IP address (from VLAN), proper gateway, proper DNS (which I set up manually in the DHCP pool config) but when I try to ping whatever IP in the outside world (say 8.8.8.8) I immediately get 'Network unreachable'. Local connections are working. I feel that I miss some routing. So when I am connected to VLAN10 (according to the tutorial I linked) my gateway is 192.168.10.1 but I can't access the Internet. What route(s) am I missing?

I don't include any drawing or sachems as my network configuration is exactly the same as specified in the link.

  • Your ISP router doesn’t know how to route traffic to your other VLANs. Normally you would configure static routes on it, but you say you can’t manage it. That’s a problem. – Ron Trunk Aug 31 '19 at 3:06
  • Well, I used wrong words. I can't manage ISP's router directly but I can call helpdesk and they can do a change for me. What routing should they add in order to reach Internet from VLANs? – janas Aug 31 '19 at 12:15
0

The ISP router needs static routes for your other VLANs. The next hop is your layer 3 switch.

| improve this answer | |
  • So, ISP's router IP is 192.168.0.1 and if I understand correctly by 'layer 3 switch' you mean switch A which serves as a DHCP server for VLANs (192.168.0.9). I set up a static route on router with destination 192.168.10.0 and next hop 192.168.0.9. When I connect to the proper port on switch B (VLAN with 192.168.10.x) I am still getting 'Network unreachable'. – janas Sep 1 '19 at 22:26
  • can you ping 192.168.0.9 from vlan 10? – Ron Trunk Sep 2 '19 at 0:07
  • Yes, I can ping 192.168.0.9 being connected to VLAN10 but I can't ping 192.168.0.1. – janas Sep 2 '19 at 22:23
  • Does switch a have a default route? – Ron Trunk Sep 3 '19 at 0:55
  • Yes, switches A and B have default routes set (static ones) - dest. 0.0.0.0/0.0.0.0 next hop 192.168.0.1. Switches can ping outside world (I checked that using internal maintenance tool) and use NTP to synchronize their time. – janas Sep 4 '19 at 0:03

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.