Can't telnet VLAN

tube

Hi,

I am creating a VLAN as you can see in the diagram.




--[ For SwA, VLAN 1 ]

---

IP Address: 10.1.1.1 255.255.255
Default gateway: 10.1.1.250

--[ For SwB, VLAN 1 ]

---

IP Address: 10.2.1.1 255.255.255
Default gateway: 10.2.1.250


--[ For SwB, VLAN 1 ]

---

IP Address: 10.3.1.1 255.255.255
Default gateway: 10.3.1.250

All PCs on different VLANs can communicate with each other successfully through the Router, but unfortunately I am unable to telnet the VLAN management, SwA or SwB, SwC.

From PC with IP address 10.3.1.5

PC>telnet 10.1.1.1

<FAIL>

Did I misconfigure something?

Thank you for your helps.

Netstudent

VLAN 1 should have it's own subnet. So each VLAN 1 interface on the switches should all be in the same subnet with the same default gateway. VLAN 1 should not be sharing subnets with other VLANS. So change the VLAN1 interface IP's for switches B and C to the 10.1.0.0 subnet with the default gateway in that subnet.

ALso make sure you do a no shut on each VLAN interface.

tech-airman

tube wrote:

Hi,

I am creating a VLAN as you can see in the diagram.




--[ For SwA, VLAN 1 ]

---

IP Address: 10.1.1.1 255.255.255
Default gateway: 10.1.1.250

--[ For SwB, VLAN 1 ]

---

IP Address: 10.2.1.1 255.255.255
Default gateway: 10.2.1.250


--[ For SwB, VLAN 1 ]

---

IP Address: 10.3.1.1 255.255.255
Default gateway: 10.3.1.250

All PCs on different VLANs can communicate with each other successfully through the Router, but unfortunately I am unable to telnet the VLAN management, SwA or SwB, SwC.

From PC with IP address 10.3.1.5

PC>telnet 10.1.1.1

<FAIL>

Did I misconfigure something?

Thank you for your helps.

tube,

Are you using 802.1q trunking?

tube

Hello tech-airman,

Yep I am using Catalyst 2950 and I think the trunk is tagged by 802.1Q. It is a simulator anyway. I am not quite sure if it will work the same way as the real Cisco Catalyst.


Hi Netstudent,

I recreate new subnets for every VLAN as you suggested. However, for VLAN 1, I use ONE subnet throughout every switch, SwA, SwB and SwC.

--[ SwA ]

---

VLAN 1:
IP Address: 172.16.16.2
Default gateway: 172.16.31.254 (the last address of the subnet)

--[ SwB ]

---

VLAN 1:
IP Address: 172.16.16.3
Default gateway: 172.16.31.254


--[ SwC ]

---

VLAN 1:
IP Address: 172.16.16.4
Default gateway: 172.16.31.254

---

Other VLAN 2, VLAN 3 and etc... each has its own subnet as you recommended.

I then use a router so that they (VLANs) can talk to each other:

--[ Router ]

---

interface f0/0.1
IP Address: 172.16.16.1 255.255.240.0


interface f0/0.2
IP Address: 172.16.32.1 255.255.240.0

interface f0/0.3
IP Address: 172.16.48.1 255.255.240.0

interface f0/0.4
IP Address: 172.16.64.1 255.255.240.0

---

However, I still cann't telnet the switch (say, when I am on VLAN 3), unless, I have to change my PC to the same subnet as the subnet for VLAN 1, for example:

My PC
IP Address: 172.16.16.10
Subnet mask: 255.255.240.0
Default gateway: 172.16.16.1 (this is the subinterface f0/0.1 on the router)

I then, telnet 172.16.16.2. It will enable me to access SwA

for SwB, telnet 172.16.16.3

Please help me if I made mistakes somewhere, because it would not be neccessary to be on the same subnet as VLAN 1 in order to access it.

Thank you.

Netstudent

Good morning tube, I hope you haven;t been up all night with this
.
It looks like you are using the wrong default gateway address on your switches with the ip default-gateway command. The DG should be the address of the router's subinterface. The reason you have to change your IP to an IP in the VLAN1 subnet is because you cannot telnet into a switch that is on another subnet unless you have properly configured the DG.

So try ip default-gateway 172.16.16.1

tube

Hello Netstudent,

You are right I stayed till late last night and now one of my eye is shut and another is half shut


You are a genius! I change subinterface f0/0.1 to default gateway of the the switch and it works!!!

Hope I will have some real switches and a router to try these things out soon.

Thank you for your great helps.

tube

Hello NetStudent,

I haven't had real cisco switches yet but I dared to ask my instructor to use his real gears. And he allowed me to do so.

I found out that I can't use native VLAN (VLAN 1) for this management purpose, but I have to create a new vlan interface, say, VLAN 5 and it will work beautifully. I really don't know why I can't use VLAN 1. VLAN 1 works on sim.

I truly love Cisco networking. It is really tough, not easy at all, but really worth it.

I hope I can learn more from you and people in here.

Cheers,