Tag Info

Hot answers tagged

21

IPv6 does not implement traditional IP broadcast, and therefore does not define broadcast addresses. In IPv6, the same result can be achieved by sending a packet to the link-local all nodes multicast group which is analogous to IPv4 multicast.


18

As it's explained incredibly well, I prefer to cut&paste the answer. This is from "The TCP/IP Guide", a must read: One important change in the addressing model of IPv6 is the address types supported. IPv4 supported three address types: unicast, multicast and broadcast. Of these, the vast majority of actual traffic was unicast. IP ...


9

No it wont traverse routers unless you setup a dhcp relay agent. Broadcast messages are only broadcasted on the broadcast domain of the host (subnet).


7

http://en.wikipedia.org/wiki/Multicast_address#Ethernet Ethernet frames with a value of 1 in the least-significant bit of the first octet of the destination address are treated as multicast frames and are flooded to all points on the network. That basically equates to any address where the second hex digit is 1, 3, 5, 7, 9, B, D, or F. When you say ...


6

In IPv4 "broadcasts" are really just sent to everyone on the local broadcast domain, which is a finite domain. Multicast is sent to a finite domain defined by a particular group. See how IPv4 'broadcasts' are just a particular subset of multicast (where the 'group' is everyone). In IPv6 they eliminated the redundant term.


6

shutdown(8) sent the message. shutdown provides an automated shutdown procedure for superusers to nicely notify users when the system is shutting down, saving them from system administrators, hackers, and gurus, who would otherwise not bother with such niceties.


5

You've got the MAC address so assuming these are brand name machines rather than generics you should be able to track down the manufacturer ( http://www.coffer.com/mac_find/ ), that may narrow you search slightly (assuming you don't have all Dell or similar). You can use the IP address and a port scanner like nmap to finger print the host and find the ...


5

It will be sent through the first interface in the route table that matches the destination, evaluated in the order static route>route>gateway>metric. If you type route print you'll see something similar to the following: Network Destination Netmask Gateway Interface Metric [Loads of entries for your various NICs, routes and static ...


5

When your computer sends a packet of data to 255.255.255.255, it will actually map that to the MAC address FF:FF:FF:FF:FF:FF. The packet is then sent out of your computer to the switch (or whatever your computer is plugged in to) with a destination of FF:FF:FF:FF:FF:FF. Switches know that packets destined for that MAC address should be sent out of all ports ...


5

Those are just DHCP messages, either your server, or another is looking to configure an interface.


5

You do not "add" a broadcast address. You direct traffic to the broadcast address of a network. The broadcast address is an entirely virtual concept, and should not be "added" or otherwise assigned to any host in normal practice. The exception to the above rule is specifying the broadcast address (using ifconfig broadcast) which is done in cases where ...


4

What you're describing isn't a broadcast-- it's just requests to a web site. That router device doesn't support port-mirroring, so you're in a bit of a challenging situation. Ideally, you'd wedge a computer between the router and the ISP on the LAN side of the firewall and sniff the traffic to determine which machine is generating the excessive requests. ...


4

Your original question has been answered by NickW above, but in case it's helpful to you the next time something like this happens, here's a quick way to tell for yourself. The last bit of that log line says "PROTO=UDP SPT=68 DPT=67". This means that the packet denied by the firewall was a UDP packet, whose source port is 68, and whose destination is port ...


4

Finally, I solved it programatically. I wrote a very small software called WinIPBroadcast which takes care of relaying the broadcast frames to all interfaces. It works using an interesting fact: it is possible to receive locally generated global broadcast packets when listening on the loopback address (127.0.0.1). WinIPBroadcast listens on the local address ...


4

Windows boxes don't respond to broadcast pings and depending on the distro quite a few Linux boxes don't either. IIRC the same applies to BSD server defaults. It's not something you generally want systems to do, certainly not recently. The problem is not with the system you are sending the broadcast out from but from the remote systems ignoring it. There ...


4

A single WINS server is sufficient. Just no backup, if there is a failure. No different than DNS in that regards.


4

Although you can do “wide-area Bonjour” (that is, Bonjour over an ordinary DNS domain with dynamic registration enabled, rather than Bonjour over multicast DNS), most built-in Mac OS X stuff isn’t designed for using it — principally because wide-area Bonjour is designed for advertising services over something more diverse than just a couple of subnets. ...


3

A broadcast assumes that everyone is interested in your packet, and all hosts need to process it. For embedded devices, it is highly unlikely that they will be able to handle the request, and thus it is usually better if they can stay in power-save mode. Using multicast instead of broadcast allows the network interface to determine in hardware whether the ...


3

Assuming this is in the context of computer comms (i.e. WiFi or ADSL) then what you're looking for is called OFDM (Orthogonal Frequency Division Multiplexing) which is specifically designed for carrying digital data. The Wikipedia link above can do a far better explanation than I can, but in simple terms the data is chunked up and then lots of individual ...


3

Not that I am in the business of defending Microsoft, but after reading through the following RFCs which attempt to define how broadcasts work, I don't think that Microsoft is necessarily violating any RFCs. IMO the problem should be fixed at the application level (i.e. directed broadcasts, not global) which will hit the appropriate routes in the routing ...


3

Linux boxes may respond. http://lwn.net/Articles/45373/ "If a Linux system (with a default configuration) receives an ARP request on one of its interfaces, and that request is looking for an IP address assigned to any of the systems interfaces, the system will respond to the ARP request through the interface that received it. This response happens even if ...


3

you can use the ip helper-address command on a vlan interface to forward all broadcasts in this vlan directly to a host (mostly used for dhcp) or to another broadcast address. example: broadcasts in vlan 10 are send directly to host 10.1.2.1 in vlan 20: interface vlan10 ip address 10.1.1.254 255.255.255.0 ip helper-address 10.1.2.1 ! interface vlan20 ...


3

The bridges act as switches, and send a broadcast frame out every interface except the one where it was received. The trick with this is the wlan interfaces, which don't behave in the same way as you'd think of a normal interface. A number of clients can be associated, but each client doesn't get sent all traffic - conceptually, think of each associated ...


3

The simpler solution is to configure a bridge, but use ebtables instead of iptables to enforce the "only broadcast packets may traverse the bridge" rule. You'd want to set the FORWARD policy to DROP and then use a rule like: ebtables -A FORWARD -s FF:FF:FF:FF:FF:FF -j DROP This would have the same effect, but should work around the difficulties you're ...


2

Well, for the most part you are right. Under proper configuration/normal operation all layer two traffic should not be able to "escape" the VLAN where it is generated. There are some scenarios (VLAN hopping and DTP negotiation comes to my mind) were the traffic can leak to other VLANs without going first through a layer 3 device (a.k.a. router). With ...


2

You need to go to the properties of the second NIC and disable the "Client for Microsoft Networks" and "File and Printer Sharing for Microsoft Networks" components; then, you should go to the advanced TCP/IP settings and disable NetBIOS over TCP/IP. It should also be good to disable automatic DNS registration and ensure no default gateway is configured on ...


2

The same as unmanaged switches; possibly with the added complexity of vLANs and similar. This is implementation specific, but generally there's no difference. Packet storms can cause latency, but that's not related to the type of packet specifically. Same as #2: Implementation specific and generally no difference. "Load" isn't a well defined term, I think ...


2

This is highly dependent on the architecture of the particular switch in question. The wide price range for a 48-port "managed switch" (e.g. under $300 to well over $10,000) should tell you there's something fundamentally different going on inside. If you didn't pay very much for your switch (and I hope you didn't), it's quite likely that multicast (and ...


2

5 mbps it is enough I have a dubt for simultaneous users and bandwidth needed Are you joking? Ok, here we go. HD video is BANDWIDTH INTENSIVE. 5mbit - yes, that is quite good. FOR ONE USER. That is ONE. 500 concurrent streams? 2500 mbit = 2.5 gigabit = 3 1gbit connections. Unless you distribute a LIVE feed, this is a LOT of problems on the storage ...



Only top voted, non community-wiki answers of a minimum length are eligible