06-09-2009 07:09 AM - edited 03-06-2019 06:09 AM
We have the IP-helper statements on our VLAN interfaces of the 4507 core, configured for DHCP; our "dhcp" server is also our DNS/active directory server. Also in our global config, we have "no ip forward-protocol udp netbios-ns" and
"no ip forward-protocol udp netbios-dgm" configured. My question is, when there is a netbios request sent (to broadcast from a client) to find an internal server, and these "no ip forward-protocol" statements are in there....where does this packet get sent? or is it just dropped?
And could these statements (being in our config) be causing some of the response time issues when clients are trying to reach these (named) servers? Thanks for any help.
06-09-2009 07:21 AM
no ip forward-protocol udp netbios-ns
no ip forward-protocol udp netbios-dgm
The above commands will drop UDP NetBIOS datagrams packets and UDP NetBIOS name query packets that are sent as well.
IP-helper statement will work if ip forward-protocol udp bootpc is turn on.
06-09-2009 07:26 AM
So if our internal clients are trying to find shares on named servers, those packets being sent will be dropped....
Perhaps this is the reason why there is such a "lag" in trying to connect to these servers? These packets are sent and dropped, but perhaps other packets (on different UDP ports) are attmepted, and a successful match is made? I'm thinking we may have to take those commands out of the globabl config.
06-09-2009 07:36 AM
I have listed some of protocols you can turn off. make sure the ones you need are turn on.
no ip forward-protocol udp biff
no ip forward-protocol udp bootps
no ip forward-protocol udp discard
no ip forward-protocol udp dnsix
no ip forward-protocol udp domain
no ip forward-protocol udp echo
no ip forward-protocol udp isakmp
no ip forward-protocol udp mobile-ip
no ip forward-protocol udp nameserver
no ip forward-protocol udp netbios-dgm
no ip forward-protocol udp netbios-ns
no ip forward-protocol udp netbios-ss
no ip forward-protocol udp non500-isakmp
no ip forward-protocol udp ntp
no ip forward-protocol udp pim-auto-rp
no ip forward-protocol udp rip
no ip forward-protocol udp snmp
no ip forward-protocol udp snmptrap
no ip forward-protocol udp sunrpc
no ip forward-protocol udp syslog
no ip forward-protocol udp tacacs
no ip forward-protocol udp talk
no ip forward-protocol udp tftp
no ip forward-protocol udp time
no ip forward-protocol udp who
no ip forward-protocol udp xdmcp
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