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VLANs leaking

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JayNEC

IS-IT--Management
Jun 5, 2002
942
US
I've seen some wierd issues with broadcasts leaking from one VLAN to another.. On a variety of HP model switches. Is this a known thing?
 
I've had one issue with a PC in one VLAN not initializing NETBIOS because of a name conflict with another PC that is in a different VLAN and should not be visible to each other.
 
Are your VLANs on different subnets and do the two pc's have addresses in those two subnets. Netbios is still tunneled in TCP/IP, so if you have where those VLANs route between each other and the pc's are named the same, then you will get a naming conflict.
 
yes, and yes. But Netbios announcements are a broadcast to the local subnet, and should not be seen on other subnets on the other side of a router!
 
I've got a similar problem, I have a 2Mb fiber link between my HQ and branch offices that was just put in (cut-over from a Point to Point T1 that used routers). Since this Bo doesn't have a router I set them up on a seperate Vlan but i see about 150k of traffic going across that line even over night when no one is in either office (i assume broadcast traffic). With the old setup overnight averages were about 30k or less.

I have the port on my 2650 in my HQ that connects to the fiber box untagged for VLAN2 (the vlan of the Branch) and not a member of any other vlan. Same with the switch (A 3com 4400 that i will be changing for a 2626) in the BO, i have the port connecting to the Fiber Box set for untagged for Vlan2 and not a member of any other vlan.

Is this the correct way to set this up?

I'm sorta new to vlans and played around with then for a few hours in testing before i cut over this network last weekend.

Thanks for any help.!
 
JayNEC,
If you will disable NetBIOS over tcp/ip this problem will go away. Sounds like you have a machine somewhere that is part of both subnets, and it is what is reporting the naming conflict (maybe your DNS server?)


"We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth." - Sherlock Holmes

 
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