New to Cisco 2950 series switches

[krazyvt9]

I am trying to install a cisco 2950 48 port switch ios 12.1 (19) to replace a old 3com hub. I have configured vlan1 with a ip address to make it managable from remote but when I plug the switch into the backbone router the switch knocks my DHCP server off line. any idea's on what I am doing wrong. Please help!!!

 

[dirtyhat]

That is an interesting problem. Did you make sure that the IP address assigned to vlan 1 is not the same IP address you are using for your DHCP server?

 

[krazyvt9]

yeah this is a strange problem. vlan1 is not the same ip as the DHCP server. same segment but not the same address. Shouldn't this just act like a dumb hub if I just assign it a address and plug it in ?

 

[dirtyhat]

The switch in a factory state is still going to break up collision domains with no need for configuration. Meaning that it functions more as a bridge than a hub.

I am not seeing how the switch being plugged into your router could cause the DHCP server to drop offline, unless there is an IP address conflict.

What exactly is happening to the DHCP server when you put the switch into your network? Also, is the original 3 COM switch still plugged into the network?

Can you supply a copy of your configuration?

 

[krazyvt9]

The DHCP server goes offline and I need to reboot the server in order to get it to work again. I try pinging it by name with no luck, This happens as soon as I power up the 2950 switch. I also had ordered a 2950sx 24 port which I tried installing on another network and it had the same results. The IP I am using on the switch has been reserved for that switch so it is not in use on the network


spanning-tree mode pvst
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
!
!
interface FastEthernet0/1
no ip address
!
interface FastEthernet0/2
no ip address
!
interface FastEthernet0/3
no ip address
!
interface FastEthernet0/4
no ip address
!
interface FastEt
no ip address
!
interface FastEthernet0/6
no ip address
!
interface FastEthernet0/7
no ip address
!
interface FastEthernet0/8
no ip address
!
interface FastEthernet0/9
no ip address
!
interface FastEthernet0/10
no ip address
!
interface FastEthernet0/11
no ip address
!
interface FastEthernet0/12
no ip address
!
interface FastEthernet0/13
no ip address
!
interface FastEthernet0/14
no ip address
!
interface FastEthernet0/15
no ip address
!
interface FastEthernet0/16
no ip address
!
interface FastEthernet0/17
no ip address
!
interface FastEthernet0/18
no ip address
!
interface FastEthernet0/19
no ip address
!
interface FastEthernet0/20
no ip address
!
interface FastEthernet0/21
no ip address
!
interface FastEthernet0/22
no ip address
!
interface FastEthernet0/23
no ip address
!
interface FastEthernet0/24
no ip address
!
interface FastEthernet0/25
no ip address
!
interface FastEthernet0/26
no ip address
!
interface FastEthernet0/27
no ip address
!
interface FastEthernet0/28
no ip address
!
interface FastEthernet0/29
no ip address
!
interface FastEthernet0/30
no ip address
!
interface FastEthernet0/31
no ip address
!
interface FastEthernet0/32
no ip address
!
interface FastEthernet0/33
no ip address
!
interface FastEthernet0/34
no ip address
!
interface FastEthernet0/35
no ip address
!
interface FastEthernet0/36
no ip address
!
interface FastEthernet0/37
no ip address
!
interface FastEthernet0/38
no ip address
!
interface FastEthernet0/39
no ip address
!
interface FastEthernet0/40
no ip address
!
interface FastEthernet0/41
no ip address
!
interface FastEthernet0/42
no ip address
!
interface FastEthernet0/43
no ip address
!
interface FastEthernet0/44
no ip address
!
interface FastEthernet0/45
no ip address
!
interface FastEthernet0/46
no ip address
!
interface FastEthernet0/47
no ip address
!
interface FastEthernet0/48
no ip address
!
interface GigabitEthernet0/1
no ip address
!
interface GigabitEthernet0/2
no ip address
!
interface Vlan1
ip address 10.105.86.6 255.255.255.128
no ip route-cache
!
ip http server
!
!
line con 0
line vty 0 4
login
line vty 5 15
login
!
end
--More--


Maybe i'm just doing something really stupid wrong but I have never had this problem before.

 

[vipergg]

From the switch can you ping the backbone router ? Don't see a ip default-gateway statement you will need that to point it to the router . Other than that this should not effect the dhcp server , I would check the server and see what the nic is set at , it should be auto/auto as that is how the switch is set . Also for any user ports on this switch you must put the "switchport host" command on all user ports . Maybe this is why the dhcp server isn't working the user ports are timing out because the way the switch is now it has to wait for the user ports to go thru the complete spanning tree cycle .

 

[vipergg]

PS also put the switchport host command on your dhcp server port . Do not put it on the uplink to the router . If you are trying to ping from off your 2950 subnet you will need to put the default-gateway statement before you are going to get a reply .

 

[Cotton9]

Since you are replacing a hub with a switch you dont' have any loops in your network. So as a quick test add 'no spanning-tree vlan 1' to the config and test everything.

Then add the 'switchport host' to all ports except those connecting to other hubs and/or switches. Check out other spanning-tree command to tune you switch to your needs.

 

[krazyvt9]

using the switchport host command worked. Thank you all for your help with my 2950 problem.