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Subnets and Network Browsing? 21

Posted by Cliff from the tropical-packet-storm-Keith dept.
photozz asks: "We are on a large network (1000+ nodes) with a mix of everything, Wintel, Unix, Linux and Mac. Lately, we have been getting broadcast storms that kill the network. Our solution is to subnet everything with routers, thus killing broadcast trafic. BUT, this will limit Windows browsing on the network to each segment. Installing Brouters will just give us the same packet storm problems we had before. How can we stop broadcast trafic while enabling Netbios resolution acros routers?"
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Subnets and Network Browsing? More

Subnets and Network Browsing?

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  • Here's what you do.

    Set up a primary and secondary WINS server. Ideally they should be on separate subnets.

    On each subnet designate two machines to be the browse masters. These should be rebooted as little as possible and should definitely NOT BE user workstations. They should be running NT or a recent version of Samba and the Browser must be turned on. Also, the Computer Browser should be running on all domain controllers.

    On _every_ other machine, turn off the computer browser. Also, set each machine to be a P-node. The easiest way to accomplish this is to assign IP's using DHCP and set the Netbiod Node Type to 0x2. Make sure all of these systems have the primary and secondary WINS servers assigned.

    You must strictly control all new machines that come onto the network and make sure that no new browsers are allowed to come up on the network.

    If you go to all of this trouble, the reward you will receive is extremely fast and reliable network browsing across subnets. I know because I've done it on a 1500 node WAN. It takes a lot of discipline that most IT departments don't have or can't enfore but it's worth the trouble in my opinion.
  • Hey,

    Everyone else has been yelling about WINS, so I won't say anything about that.

    I recommend getting an L3 Switch (which is essentially a router with only RJ45 Jacks).

    Depending on how many subnets you want, Cisco has one for $10,000 which has 48ports, or SMC has a 16 port version for around $2000. I put the SMC Tigerswitch on our network and it works great.

    An L3 switch works by creating vlans that can be subnets. The main difference between this and an L2 switch is that it bridges the vlans when traffic is destined for another subnet (routing).

    have fun.
  • wins works... mostly.....

    anyway
    if memory serves, newer versions of IOS allow you to get the dumb wintel boxen to browse off their segment w/o wins.... i dont remember how it works.

    sorry
    good luck

  • It really should be of no worry to you - a broadcast is a packet that is sent to multiple machines. It is an issue on a large network because all of the machines are sending broadcast messages in order to locate other machines. Since you will be pretty much segmented off, it should not be an issue.

  • I run a UNIX/Samba LAN. I use only UNIX/Samba for file/print services. We use WINS on all our clients, including talking to other subnets.

    Unfortunately, I have one NT Server for a SQL application (that I fought, and lost, to keep off my network -- only 3 people use it). I do not use named pipes on it at all and tell it to use WINS for NetBIOS resolution. But the f'er sends out more broadcasts that all other (50) systems combined (an average of ~10/second). I have tried tweaking this thing 10 ways to Sunday and cannot get it to stop the chatter (and yes, I've told it to NOT be the local master).

    Case in point, if get NT Servers off your network, you'll cut the chatter several times over. I'm much more of an expert at Samba than NT, but after 8 years experience with NT, I think I know somewhat of I'm doing (although I'll take any suggestions at this point ;-).

    P.S. I was the contributing author on Samba Unleashed and wrote Chapter 33 on "Cross Subnet Browsing" (which was a last second rush job, otherwise I would have added info to fix exactly the issues you are having by replacing NT with Samba). IMHO Samba is just so much better at running large WANs with multiple subnets!

    -- Bryan "TheBS" Smith

  • Use an NT domain.
    The Domain Master Browser should pick up everything.
  • No. THat lets anyone resolve any name, but does not provide 'brosable' lists of all hosts on the network.
    Just as DNS does not provide a list of who is where when.
  • I can't believe that you are running 1000+ nodes and don't know about WINS. Try buying a book and reading up on WINS.

  • Troubleshooting technique (Score:3)

    by adjuster ( 61096 ) on Saturday October 14, 2000 @02:48PM (#705609) Homepage Journal

    Have you used a sniffer to see what this "broadcast storm" traffic is? That would do for a good start. A description of the issue other than "kill the network" would do more good as well. What kind of byte/sec and packet/sec counts are we seeing on the media?

    Assuming it is broadcast related: Your 'doze boxes need to be using "H-Node" name resolution for their cruddy NetBIOS name resolution. You need WINS servers. You need to disuse protocols that are broadcast intensive.

    To the guys that are saying "install a switch"-- apparently there's an understanding issue w/ regard to what a switch does. A layer-2 switch won't help a bit in this case-- just like the poster said (referring to bridging routers). An analysis of what the traffic on the wire is would be a great first step. Then, intelligent decisions can be made to address the problem. Layer-3 switching might be a potential solution, depending on what the traffic is.

    Unless you're using layer-3 entities inside of switches, your router based solution is going to do more than mess up NetBIOS name service-- it'll slow everything down to a crawl. Most low-end routers don't even come close to wire-speed.

    I had a customer swearing to me that they were having "broadcast storms" because they were getting massive numbers of collisions on a shared-media LAN. We took a look at it w/ a sniffer and discovered that broadcasts played no part in it. They were doing large file transfers to a machine that was dual-homed on the same physical NIC, and the machine was thrashing packets on and off the wire, "routing" the packets to two hosts that were in different subnets, but on the same media. Duh.

    Don't assume you know what your problem is unless you know what your problem is...

  • WINS (Score:1)

    by fznck ( 74767 )
    Install a WINS server (windows internet name server server) for the NetBIOS machines. A samba machine can do it. Windows 3+, 95, 98, Me, NT, 2000 can all use it (unlike active directory). Adjust your DHCP server or point all NetBIOS nodes to this wins server, enable h-node (just in case the wins server fails, h-node will broadcast for resolution if it can't reach the wins server) resolution, and you're set.
  • People may say a lot of bad things about Microsoft, but they really do have a pretty good knowledgebase compared to many of their competitors. With questions like this, one should visit support.microsoft.com [microsoft.com] (or if it is programming related, msdn.microsoft.com [microsoft.com])

    Without WINS:

    Q117633 - How Browsing a Wide Area Network Works [microsoft.com]

    The proper way to do it, though, would be to set up a WINS server and WINS Proxy agents:

    w inNT Mag article on WINS [winntmag.com] - actually, do a search on this site for "WINS" and you'll find several other usefull articles.
    Q121004 - WINS Proxy Agent Functionality [microsoft.com]

    Also usefull:

    Q142692 - Minimizing WAN Traffic [microsoft.com]

    -jerdenn

  • We have a similar problem (300+ nodes) and its not the broadcasts that kill us its when someone transfers something over windows file sharing it creates about 80% packet loss for everthing on that segment of the network (each segment is about 4 or 5 hubs uplinked to a master switch). Sniffer shows NetBIOS Session Services just blasting all over the place and its with any windows machine, not just a few. Suggestions (other than get rid of the windows ;) ?
  • How about using a switch, which would separate your network into diferent collision domains, but still maintaining the NetBIOS browsing intact.
    Or, as was jsut mentioned, setting up routers, and subsequently putting a WINS server on the network to handle NetBIOS names.
  • I have two words for you:
    man nmbd

    Yes, all you need is a WINS server to have netbios resolution without broadcasts. Yes, Samba (available on most major unix platforms, including Linux) has a WINS server. Try samba.org. Here's how it works: Netbios system (such as Win98) boots up and notifies WINS server (specified in TCP/IP settings) of it's name and IP address. Next time some computer requests that name (or IP address for reverse-lookups) it asks the WINS server (via UNI-case packet), and the WINS server tells it. This happens everytime you \\compname\resource.

    I hope that helps, without me being too much of a meanie.
  • Sounds wierd, but im doing semester 3 of CCNA studies, and one method is to set up VLANs for your network, and connect them all to a router to make them talk to each other. As VLANs restrict broadcast domains, and routers can talk between VLANs, you'd fix the problem without having to mess with subnetting:) Less of a headache than walkin from station to station redoing tcp/ip settings:P
  • ahem, in response to all the WINS answers, we HAVE wins enabled, But the wins setup is not allowing us to browse the network. We can find any computer by name, (I.E.: running \\computername or using "find computer")but we can't open "Network Neiborhood" and see computers on other subnets. A wins server on other subnets is unable to push/pull with the primary wins server.

  • OKiedoke, but this would involve converting 250+ servers and databases. can we say political suicide? We just signed (Not me, someone else..)an enterprise level agreement with $MS, so were stuck.

  • remove the hubs and go to swiches, should cut down on broadcast trafic, and increase your speed.

  • Hrmm... Maybe some 'concerned citizen' should send this off to to admin at that college who was trying to control the dorm-rats' use of napster and whatnot. He mentioned in a secondary post that his network was something like 90% broadcast crap from various windows boxen..

    Me, I'm going to bed.
  • What protocol(s) are you using. You say

    How can we stop broadcast trafic while enabling Netbios resolution acros routers?"

    I'm tempted to conclude you're not using NetBEUI, but it seems prudent to ask -- it's not on any machine in the network, is it?

  • One way to solve with would be to subnet the network, but then setup a WINS server. This should let everyone see everything on the network with out sending a broadcast packets.

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