Netbios name resolution is not working across subnets.

[jsarausos]

Hi,

I have a problem with our network.  We recently changed our old core switches (Cisco 6509) running on CatOs to a Cisco 6506-E running on IOS.  Previously netbios name resolution is working across subnets.  The hostname for printer located on subnet X can only be resolved by clients on subnet X and subnet Y.  Now, after the changed of our core switches, subnet Y cannot resolved the hostname of the printer located on subnet X.

The DHCP Server is also running WINS server and all of the clients are pointing to their WINS server as well.

There should be no problem with regards to any server configuration because previously it was working fine, only when we had changed our core switches then we had this issue.

Could there be any services running on the previous version using CatOs that helped in the name resolution? While in the new IOS, these services are disabled by default?

Old Core:

=====

****************** show version ******************

WS-C6509 Software, Version NmpSW: 7.1(2)
Copyright (c) 1995-2002 by Cisco Systems
NMP S/W compiled on Feb  7 2002, 17:12:47

System Bootstrap Version: 7.1(1)

New Core:

=======

------------------ show version ------------------

Cisco IOS Software, s72033_rp Software (s72033_rp-IPSERVICESK9_WAN-VM), Version 12.2(33)SXH8, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2010 by Cisco Systems, Inc.
Compiled Wed 29-Sep-10 09:47 by prod_rel_team

ROM: System Bootstrap, Version 12.2(17r)SX7, RELEASE SOFTWARE (fc1)

Even-CS uptime is 4 hours, 9 minutes
Uptime for this control processor is 4 hours, 8 minutes
Time since Even-CS switched to active is 4 hours, 8 minutes
System returned to ROM by  power cycle at 03:37:53 UTC Thu Jan 20 2011 (SP by power on)
System image file is "sup-bootdisk:s72033-ipservicesk9_wan-vz.122-33.SXH8.bin"

Your expert help is highly appreciated.

Thanks!

Best regards,

Jayson Sarausos

[cadet alain]

Hi,

Your Windows machines are surely configured as B-nodes and so they will never try to contact the WINS server but will broadcast for NETBIOS name resolution and your switch will not flood this broadcast in the other VLAN or if it is working as a router it will stop this broadcast and you'll have to implement ip helper.But the best would be to configure your hosts as M-nodes so they will first try unicast to WINS and if it fails then they will broadcast.

Regards.

Alain.

[jsarausos]

Hi Alain,

My configuration already have ip-helper configured.  Please see below snippet of the configuration:

interface Vlan107
ip address 172.88.107.2 255.255.255.0
ip helper-address 172.88.108.16
no ip redirects
standby preempt
standby 107 ip 172.88.107.1
standby 107 priority 90
!
interface Vlan108
ip address 172.88.108.2 255.255.255.0
ip helper-address 172.88.108.16
no ip redirects
standby preempt
standby 108 ip 172.88.108.1
standby 108 priority 110

How do I configure my hosts as M-Nodes? and how to know if what nodes are my host configured?

Thanks!

Best Regards,

jsarausos

[Antonio Knox]

cadetalain,

M-Nodes actually broadcast first, then they query the name server by unicast. 

http://support.microsoft.com/kb/119493

Here is how you configure it, should you decide to use the feature.

http://support.microsoft.com/kb/181171

I think what you meant to suggest was H-Mode.  This mode unicasts to the name server first, then attempts a brodcast if unicast fails.

http://support.microsoft.com/kb/314053

Hope this helps.

[cadet alain]

Hi Antonio,

I think what you meant to suggest was H-Mode

Good catch 

[cadet alain]

Hi,

ip address 172.88.108.2 255.255.255.0
 ip helper-address 172.88.108.16

What's the use of ip helper here?

I see you are using HSRP is this the Active router in Vlan107? if  no did you set ip helper on the other?

Regards.

Alain.

[jsarausos]

Hi Alain,

We are using DHCP in our network, that is why we need to have an IP helper.  I have checked on the clients IP configuration and they are pointing to the WINS server which is also the DHCP server, however they are still not able to resolve the netbios across the subnets.

[cadet alain]

 I have checked on the clients IP configuration and they are pointing to the WINS server which is also the DHCP server

Have you checked the NETBIOS node type as stated in previous post?

Can you ping this WINS server from client?

Regards.

Alain.