No internet on specific IP range!!!

jhammond · January 31, 2014

Hi All,

Just a quick question (hopefully!)

On my network we have one DHCP server; the ip address starts at 192.168.0.1 and ends at 192.168.1.254 with a subnet mask of 255.255.254.0.

Any machine that connects with an ip address in the 192.168.0. range can connect to the internet with no problems, however any machine that is assigned an ip in the 192.168.1. range cannot access the internet at all.

I cannot ping 8.8.8.8 or bbc.co.uk or even perform a tracert. I can however ping the router at 192.168.1.254.

I have spoken to the internet providers and they have assured me that the router is set to the same 255.255.254.0 range.

Any advice would be much appreciated as we are constantly running our of room on the DHCP Scope.

cheers guys!!

Mr.Ben · January 31, 2014

What subnet mask is DHCP handing out for th 192.168.1 range?

jhammond · January 31, 2014

the subnet mask for this is also 255.255.254.0

featured_spectre · January 31, 2014

why isn't it dishing out on the 255.255.255.0 range?

jhammond · January 31, 2014

ive just taken over the network at the school and this was the state I found it in; not the greatest. The subnet mask has already been set to 255.255.254.0. This was all created by the dreaded RM network technicians I believe

featured_spectre · January 31, 2014

Ahh I see. Well I would assign a private IP range and start moving people.

10.9.1.x - 10.9.3.x For Admin machines

10.9.4.x - 10.9.7.x For Teaching machines

10.9.8.x - 10.9.10.x For student machines

10.9.11.x - 10.9.30.x For anything else

All should work on the 255.255.254.0

jhammond · January 31, 2014

That is something that I do want to do, but was going to be a holiday job, as there are currently no VLAN's setup.

The main switch is a Cisco SG200-50

featured_spectre · January 31, 2014

You can set the VLANs up now, and start shifting people in batches. For example, do an IT class room, put it out of use for a day for maintenance. Rinse and repeat around the school

jhammond · January 31, 2014

true; but I am tight for time at the moment as I am the only technician in the school, that's why I was wondering if there was an obvious reason why my current range would not work!

SkreeM1980 · January 31, 2014

So, What is the default gateway being recieved by clients?

Can you paste and ipconfig from a host which does work and a host which doesn't prefereably alongside the results of route print

P.S. I am using subnet mask of 255.255.254.0 on a couple of VLAN's so know it works fine

jhammond · January 31, 2014

this is the ipconfig when the internet works and the route print

Connection-specific DNS Suffix . :

Description . . . . . . . . . . . : Intel® 82579V Gigabit Network Connectio

n

Physical Address. . . . . . . . . : 74-27-EA-53-45-38

DHCP Enabled. . . . . . . . . . . : No

Autoconfiguration Enabled . . . . : Yes

Link-local IPv6 Address . . . . . : fe80::20f9:4973:4f74:cbcd%10(Preferred)

IPv4 Address. . . . . . . . . . . : 192.168.0.200(Preferred)

Subnet Mask . . . . . . . . . . . : 255.255.254.0

Default Gateway . . . . . . . . . : 192.168.1.254

DHCPv6 IAID . . . . . . . . . . . : 242493418

DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1A-25-0C-87-74-27-EA-53-45-38

DNS Servers . . . . . . . . . . . : 192.168.0.1

NetBIOS over Tcpip. . . . . . . . : Enabled

Interface List

10...74 27 ea 53 45 38 ......Intel® 82579V Gigabit Network Connection

1...........................Software Loopback Interface 1

11...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface

15...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3

===========================================================================

IPv4 Route Table

===========================================================================

Active Routes:

Network Destination Netmask Gateway Interface Metric

0.0.0.0 0.0.0.0 192.168.1.254 192.168.0.200 266

127.0.0.0 255.0.0.0 On-link 127.0.0.1 306

127.0.0.1 255.255.255.255 On-link 127.0.0.1 306

127.255.255.255 255.255.255.255 On-link 127.0.0.1 306

192.168.0.0 255.255.254.0 On-link 192.168.0.200 266

192.168.0.200 255.255.255.255 On-link 192.168.0.200 266

192.168.1.255 255.255.255.255 On-link 192.168.0.200 266

224.0.0.0 240.0.0.0 On-link 127.0.0.1 306

224.0.0.0 240.0.0.0 On-link 192.168.0.200 266

255.255.255.255 255.255.255.255 On-link 127.0.0.1 306

255.255.255.255 255.255.255.255 On-link 192.168.0.200 266

===========================================================================

Persistent Routes:

Network Address Netmask Gateway Address Metric

0.0.0.0 0.0.0.0 192.168.1.254 Default

===========================================================================

IPv6 Route Table

===========================================================================

Active Routes:

If Metric Network Destination Gateway

1 306 ::1/128 On-link

10 266 fe80::/64 On-link

10 266 fe80::20f9:4973:4f74:cbcd/128

On-link

1 306 ff00::/8 On-link

10 266 ff00::/8 On-link

===========================================================================

Persistent Routes:

None

and here is the one wen there is no internet

Connection-specific DNS Suffix . :

Description . . . . . . . . . . . : Intel® 82579V Gigabit Network Connectio

n

Physical Address. . . . . . . . . : 74-27-EA-53-45-38

DHCP Enabled. . . . . . . . . . . : No

Autoconfiguration Enabled . . . . : Yes

Link-local IPv6 Address . . . . . : fe80::20f9:4973:4f74:cbcd%10(Preferred)

IPv4 Address. . . . . . . . . . . : 192.168.1.200(Preferred)

Subnet Mask . . . . . . . . . . . : 255.255.254.0

Default Gateway . . . . . . . . . : 192.168.1.254

DHCPv6 IAID . . . . . . . . . . . : 242493418

DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1A-25-0C-87-74-27-EA-53-45-38

DNS Servers . . . . . . . . . . . : 192.168.0.1

NetBIOS over Tcpip. . . . . . . . : Enabled

Microsoft Windows [Version 6.1.7601]

C:\Users\systemadmin.STCATHERINES>route print

===========================================================================

Interface List

10...74 27 ea 53 45 38 ......Intel® 82579V Gigabit Network Connection

1...........................Software Loopback Interface 1

11...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface

15...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3

===========================================================================

IPv4 Route Table

===========================================================================

Active Routes:

Network Destination Netmask Gateway Interface Metric

0.0.0.0 0.0.0.0 192.168.1.254 192.168.1.200 266

127.0.0.0 255.0.0.0 On-link 127.0.0.1 306

127.0.0.1 255.255.255.255 On-link 127.0.0.1 306

127.255.255.255 255.255.255.255 On-link 127.0.0.1 306

192.168.0.0 255.255.254.0 On-link 192.168.1.200 266

192.168.1.200 255.255.255.255 On-link 192.168.1.200 266

192.168.1.255 255.255.255.255 On-link 192.168.1.200 266

224.0.0.0 240.0.0.0 On-link 127.0.0.1 306

224.0.0.0 240.0.0.0 On-link 192.168.1.200 266

255.255.255.255 255.255.255.255 On-link 127.0.0.1 306

255.255.255.255 255.255.255.255 On-link 192.168.1.200 266

===========================================================================

Persistent Routes:

Network Address Netmask Gateway Address Metric

0.0.0.0 0.0.0.0 192.168.1.254 Default

===========================================================================

IPv6 Route Table

===========================================================================

Active Routes:

If Metric Network Destination Gateway

1 306 ::1/128 On-link

10 266 fe80::/64 On-link

10 266 fe80::20f9:4973:4f74:cbcd/128

On-link

1 306 ff00::/8 On-link

10 266 ff00::/8 On-link

===========================================================================

Persistent Routes:

None

C:\Users\systemadmin.STCATHERINES>

featured_spectre · January 31, 2014

is the gateway and DNS the same for the machine next to it?

FN-GM · January 31, 2014

Unless I am mistaken 255.255.254.0 isn't an option for a Class C network? Edited January 31, 2014 by FN-GM

mac_shinobi · January 31, 2014

Unless I am mistaken 255.255.254.0 isn't an option for a Class C network?

Looking here : Codebox Software - IP Network Address Calculator

Shows its a /23 cidr

[TD="class: outputName"]Subnet Netmask
[TD="class: outputValue"]255.255.254.0

[TD="class: outputName"]Network
[TD="class: outputValue"]192.168.0.0/23

[TD="class: outputName"]Min Host
[TD="class: outputValue"]192.168.0.1

[TD="class: outputName"]Max Host
[TD="class: outputValue"]192.168.1.254

[TD="class: outputName"]Broadcast Address
[TD="class: outputValue"]192.168.1.255

[TD="class: outputName"]Max Hosts on Subnet
[TD="class: outputValue"]510

Edited January 31, 2014 by mac_shinobi

SkreeM1980 · January 31, 2014

Unless I am mistaken 255.255.254.0 isn't an option for a Class C network?

/23 is just a supernet of 2 class C scopes joined together it should be no problem at all.

SchoolsBroadband · January 31, 2014

Can a computer with an ip range on 192.168.0.x ping any other computer (not the gateway) on 192.168.1.x ??

I'm wondering if each subnet has been attached to a different NIC on the router gateway and has some funny access lists on it.

Dave

SkreeM1980 · January 31, 2014

The IP config and Routing table all look brilliant.

Do you get ping response from the gateway?

SchoolsBroadband · January 31, 2014

the one thing I'm also not sure of is why do you have persistent routes set on the PC? There is no need for persistent routes as the default gateway is set via DHCP

I'd suggest removing them from a test machine. the commands to do in this order

route delete 0.0.0.0

ipconfig renew

arp flush

Also do an "arp -a" command on a machine on the 192.168.0.x range and the 192.168.1.x range. Then see if the MAC address is the same for the 192.168.1.254 (gateway router address). If its not then perhaps you have 2 different routers on the same IP address on the network?!

Really clutching at straws here but I've seen odder things.

Dave

mac_shinobi · January 31, 2014

the one thing I'm also not sure of is why do you have persistent routes set on the PC? There is no need for persistent routes as the default gateway is set via DHCP

I'd suggest removing them from a test machine. the commands to do in this order

route delete 0.0.0.0
ipconfig renew
arp flush

Also do an "arp -a" command on a machine on the 192.168.0.x range and the 192.168.1.x range. Then see if the MAC address is the same for the 192.168.1.254 (gateway router address). If its not then perhaps you have 2 different routers on the same IP address on the network?!

Really clutching at straws here but I've seen odder things.

Dave

@SchoolsBroadband

Not sure if this has any bearing on any of this but if you look at both ipconfig's , it is showing as DHCP Disabled / off

DHCP Enabled. . . . . . . . . . . : No

SchoolsBroadband · January 31, 2014

@SchoolsBroadband

Not sure if this has any bearing on any of this but if you look at both ipconfig's , it is showing as DHCP Disabled / off

DHCP Enabled. . . . . . . . . . . : No

doh good point

Synkrox · February 2, 2014

Your subnet and all that look good to me. I suspect your gateway/router or proxy is running on a 255.255.255.0 subnet so wont respond. Chances is are that's how it was set up originally and someone expanded the subnet at some point without finishing the job!

No need for all the VLAN stuff, it'll be a simple fix :-)

jhammond · February 3, 2014

I can ping te default gateway when on the 192.168.1. range

jhammond · February 3, 2014

Hi Synkrox,I have spoken to RM (who host the router and have access to it) and they state that this is running on 255.255.254.0. I have used a cross over cable and plugged a laptop directly into the router and used the DNS server address they have given me and my ip address of 192.168.1.150 and this works. So i do not believe it is a config error on the router!

Synkrox · February 3, 2014

Perhaps your proxy doesn't have an ACL/Policy for that subnet to pass traffic then?

(edit: just saw your previous post) - I'm stumped then. If you have a machine on that IP range keep moving it one device further away from the router until it stops working. With a flat network no reason for traffic not to be passed.

Edited February 3, 2014 by Synkrox

SkreeM1980 · February 3, 2014

Hi Synkrox,I have spoken to RM (who host the router and have access to it) and they state that this is running on 255.255.254.0. I have used a cross over cable and plugged a laptop directly into the router and used the DNS server address they have given me and my ip address of 192.168.1.150 and this works. So i do not believe it is a config error on the router!

Ok,

So what exists between your client computers and the router?

Did you say that you can't get a traceroute to a public internet address? (8.8.8.8 for example)

No internet on specific IP range!!!

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