Vlans and Internet connection

andyferguson1977 · ‎08-17-2018

Vlans and internet connection

So, I'm a little confused.

So i have 3 Vlans created.

Vlan 1 - Port 1 - 16

Vlan 50 Port 17 - 32

Vlan 100 Port 33 - 48

They each have their own dhcp server etc.

Which port should i connect my comcast cable to. Should I have configured 1 port not to be apart of any vlan and connect it there. Please advise. Not sure where to go from here

See configuration below.

Thanks

Switch#show config
Using 4362 out of 524288 bytes
!
version 12.2
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Switch
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
switch 1 provision ws-c3750g-48ts
system mtu routing 1500
ip subnet-zero
no ip dhcp use vrf connected
!
ip dhcp pool vlan50
network 192.168.50.0 255.255.255.0
default-router 192.168.50.1
!
ip dhcp pool vlan100
network 192.168.100.0 255.255.255.0
default-router 192.168.100.1
!
!
!
!
!
!
!
!
!
!
spanning-tree mode pvst
spanning-tree etherchannel guard misconfig
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
!
!
!
interface GigabitEthernet1/0/1
!
interface GigabitEthernet1/0/2
!
interface GigabitEthernet1/0/3
!
interface GigabitEthernet1/0/4
!
interface GigabitEthernet1/0/5
!
interface GigabitEthernet1/0/6
!
interface GigabitEthernet1/0/7
!
interface GigabitEthernet1/0/8
!
interface GigabitEthernet1/0/9
!
interface GigabitEthernet1/0/10
!
interface GigabitEthernet1/0/11
!
interface GigabitEthernet1/0/12
!
interface GigabitEthernet1/0/13
!
interface GigabitEthernet1/0/14
!
interface GigabitEthernet1/0/15
!
interface GigabitEthernet1/0/16
!
interface GigabitEthernet1/0/17
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/18
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/19
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/20
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/21
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/22
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/23
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/24
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/25
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/26
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/27
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/28
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/29
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/30
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/31
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/32
switchport access vlan 100
switchport mode access
!
interface GigabitEthernet1/0/33
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/34
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/35
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/36
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/37
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/38
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/39
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/40
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/41
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/42
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/43
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/44
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/45
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/46
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/47
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/48
switchport access vlan 50
switchport mode access
!
interface GigabitEthernet1/0/49
!
interface GigabitEthernet1/0/50
!
interface GigabitEthernet1/0/51
!
interface GigabitEthernet1/0/52
!
interface Vlan1
ip address 192.168.1.254 255.255.255.0
!
interface Vlan50
ip address 192.168.50.1 255.255.255.0
!
interface Vlan100
ip address 192.168.100.1 255.255.255.0
!
ip classless
ip http server
ip http secure-server
!
!
!
!
control-plane
!
!
line con 0
line vty 5 15
!
end

Georg Pauwen · ‎08-17-2018

Hello,

what Comcast device do you have ? Which switch do you have (which model, e.g. 2960) ?

andyferguson1977 · ‎08-18-2018

Cisco 3750G and for Comcast it's the

Model:DPC3941T

Vendor:Cisco

Georg Pauwen · ‎08-18-2018

Hello,

you have a DOCSIS modem which I don't think you can configure to do address translation for more than the default network (10.x.x.x).

Your 3750G cannot do address translation, so it doesn't matter which port you connect the modem to. Only ports in the default VLAN 1 will be able to access the Internet (as these are getting IP addresses in the 10.x.x.x range)...

andyferguson1977 · ‎08-18-2018

ok

So my computes that are connect to vlan 50 and vlan 100 will not be able to go online

paul driver · ‎08-18-2018

Hello

Only high switching platforms supports NAT ( 6500+) so to provide NAT for you local subnet you'll need to put a router in between your Comcast and the 3750.

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

andyferguson1977 · ‎08-22-2018

Instead of a router can I use a ASA 5510 firewall

andyferguson1977 · ‎08-22-2018

I just don't understand why my computers in vlan 50 and vlan 100 will not be able to go online.

Neil Sheridan · ‎08-22-2018

For any edge device to access the internet the private address will need to be translated to a public 'routable' address. This is accomplished via NAT (Network Address Translation). You will need a device that is capable of NAT and routing. Think back to CCENT and CCNA studies, all traffic that traverses one subnet to another (Layer 3) needs to be routed. If you are also wanting to have multiple devices accessing the internet (sharing one public IP) you must NAT this traffic (overload).

HTH

N