Internet Connection dropping off at random times.

[RBM01991]

Good afternoon Team,

I am studying for my CCNA exam, and in efforts to do so, I purchased a Cisco C4948 Series switch and installed it as my main switch in my "network closet".

The network layout is pretty simple, I have my Frontier FiOS router plugged into port 1 of the switch and my other devices in the other ports.

I have 1 VLAN configured, with ports 1-16 belonging to that VLAN. No port security, no firewall rules other than the ones that come with the FiOS router by default and nothing else. My default gateway is still my FiOS router.

The issue is the at random times when the switch has been idle for hours, all my devices will lose connection. They will get an APIPA address and I will have to boot up Putty and I usually type in show vlan and it normally comes back up in a couple of minutes.

I can fix it, but its really annoying to have to do that all the time, so what do you guys recommend I do to stop this from happening permanently?

[Georg Pauwen]

Hello,

hard to say. The 4948 is end of life/end of sale for a while now, so maybe it is a hardware issue. Post the full running configuration of the switch, maybe we can spot something.

[RBM01991]

Georg.

Thanks for the reply, here's the running config of the switch.

Switch#show running-config
Building configuration...

Current configuration : 3023 bytes
!
version 12.2
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service compress-config
!
hostname Switch
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
ip subnet-zero
!
!
!
!
no file verify auto
spanning-tree mode pvst
spanning-tree extend system-id
power redundancy-mode redundant
!
!
!
vlan internal allocation policy ascending
!
interface GigabitEthernet1/1
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/2
description Server
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/3
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/4
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/5
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/6
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/7
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/8
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/9
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/10
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/11
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/12
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/13
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/14
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/15
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/16
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/17
!
interface GigabitEthernet1/18
!
interface GigabitEthernet1/19
!
interface GigabitEthernet1/20
!
interface GigabitEthernet1/21
!
interface GigabitEthernet1/22
!
interface GigabitEthernet1/23
!
interface GigabitEthernet1/24
!
interface GigabitEthernet1/25
!
interface GigabitEthernet1/26
!
interface GigabitEthernet1/27
!
interface GigabitEthernet1/28
!
interface GigabitEthernet1/29
!
interface GigabitEthernet1/30
!
interface GigabitEthernet1/31
!
interface GigabitEthernet1/32
!
interface GigabitEthernet1/33
!
interface GigabitEthernet1/34
!
interface GigabitEthernet1/35
!
interface GigabitEthernet1/36
!
interface GigabitEthernet1/37
!
interface GigabitEthernet1/38
!
interface GigabitEthernet1/39
!
interface GigabitEthernet1/40
!
interface GigabitEthernet1/41
!
interface GigabitEthernet1/42
!
interface GigabitEthernet1/43
!
interface GigabitEthernet1/44
!
interface GigabitEthernet1/45
!
interface GigabitEthernet1/46
!
interface GigabitEthernet1/47
!
interface GigabitEthernet1/48
!
interface Vlan1
no ip address
!
interface Vlan100
ip address 192.168.1.2 255.255.255.0
!
ip default-gateway 192.168.1.1
ip route 0.0.0.0 0.0.0.0 192.168.1.1
no ip http server
!
!
!
!
!
line con 0
stopbits 1
line vty 0 4
no login
!
!
end

[RBM01991]

Georg.

I have found the problem, there's a block on the spanning tree protocol that prevents DHCP from giving out addresses for the first 30-90 seconds of a device coming onto the network. Now on an enterprise production scenario, you would just have to deal with it or find a different way to get it done, if you were trunking as the block prevents loops...however, this is my home switch, so I don't have to worry about that.