Cannot see 2600 router through catalyst 2950 switch

[lang1armean]

Hello,

New to Cisco so please bare with me. I am having trouble  connecting the Cisco 2600 to the Catalyst 2950. All ports on switch are set to Vlan 1 and show status as being connected except those not connected to anything of course. However, Interface Fa0/1 is showing NOT connected with the router connected to it.

I have reset the switch:

flash_init

load_helper

boot

then i configure IP address and Gatewway, but still show status as "not connected"

Looking for a starting point please.

Much Appreciated,

Mark L

[John Forester]

You're Welcome Mark! Glad to hear that it is working.

If you get (or make) a rolled T1 cable, you can connect two of your routers to each other's T1 ports, and on router 1's ethernet port can connect to the Internet connection, while the other router goes to your switch as you have it set up now. This will require some configuring, but is cheaper than buying a card.

I am including a drawing to help show what I mean.

Good Luck!!

[Marcel Tempelman]

There is an easier way:

Create a seperate Internet VLAN on your switch (assuming vlan 1 is your plain data VLAN): e.g. vlan999.

Setup fa0/24 as follows:

int fa0/24

 description ** Internet **

 switchport mode access

 switchport access vlan 999

 spanning-tree portfast

!

Create a trunk port for the router

int fa0/23

 switchport mode trunk

!

Setup a trunk port on the router:

int fa0/0

 no ip address

!

fa0/0.1

 encapsulation dot1q 1 native

 ip address 192.168.1.1 255.255.255.0

 ip nat inside

!

int fa 0/0.99

 encapsulation dot1q 99
 ip address DHCP

 ip nat outside

!

Setup NAT

ip nat inside source NAT-ACL interface fa0/0.99 overload

ip access-list extended NAT-ACL

 10 permit ip 192.168.1.0 0.0.0.255 any

!

What this solves is your lack of ethernet ports on your router by using some of your switch ports.

[lang1armean]

i did get the network connection working from routers eth port to the switch and can ping the router

[John Forester]

Oops - very sorry that I missed this, but it didn't hit me until the drive home. I just verified that this works from my lab.

The issue is that your switch is running as a layer 2 device, so if you are going to layer 3 from layer 2, it has to have an IP that it can get to on that VLAN at layer 3. Hence you need to configure your uplink to the router as a trunk port, not a switchport on the switch. And you need to configure the VLAN on the router using a sub-interface and VLAN ID of 1. Hope this makes sense....

Here are the configs

Switch

interface FastEthernet0/1
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 1
 switchport mode trunk

no ip default-gateway 192.168.10.25

your other interfaces would be access ports and vlan 1, or just access if you have no other vlans

interface FastEthernet0/3
 switchport mode access

On the router, you configure the sub-interface and vlan info as follows:

interface FastEthernet0/0.1
 encapsulation dot1Q 1 native
 ip address 192.168.10.25 255.255.255.0

if you decide to add another VLAN later, just put in:

interface fa0/0.5

encapsulation dot1q 5

ip address 192.168.5.1 255.255.255.0

and on the switch you simply modify your trunk port line

interface FastEthernet0/1
  switchport trunk allowed vlan 1, 5

then assign access ports to VLAN 5 as needed

Hope this helps and sorry for the other post - please disregard

p.s. As a security precaution, it is good practice to not use VLAN 1 - many places I've worked at do not use it, and instead use other VLANs. They shut down VLAN 1.