Questions tagged [broadcast]

For questions about broadcasting in computer networking. Use this tag when you are troubleshooting or configuring network devices in relation to broadcast.

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Broadcasting in L2 Switch

Hey guys, This is a Noob question. When a broadcast frame is received on a switch from a specific port, will it be automatically destined to all the ports in a switch ? ---------- (or) ---------- ...
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3answers
1k views

Why do we have to connect through a default gateway in a LAN?

I'm a beginner in networking and I'm looking for answers for these questions: Why do we have to connect through a default gateway when we are connected to a LAN and want to connect to another devices ...
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420 views

What WIFI AP to broadcast 3 Mbps UDP stream?

CONTEXT: We are searching for WIFI AP able to broadcast UDP stream on a maximum number of connections: 10, 30, 50, 100, 150, 200 (guess the WIFI point is different in term of price and technology ...
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1answer
4k views

What is the difference between ARP and BUM Traffic?

Suppose PC1 with IP address 1.1.1.1 and MAC address A.A.A.A wants to send a frame to PC2 with IP address 2.2.2.2 and MAC address B.B.B.B, plus there is a switch in the middle. PC1 doesn't know where ...
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2answers
1k views

How do broadcast communications work between hosts with different Subnet Masks?

Let's say I have three different hosts connected by a Layer 2 Switch: A) IP 1.0.0.1, Subnet 255.255.255.0, B) IP 1.0.0.2, Subnet 255.255.0.0, C) IP 1.0.1.1, Subnet 255.255.255.0, Who would a ...
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3answers
18k views

What are the reasons for not putting multiple subnets on the same VLAN?

I would like to know why we do not (and should not I guess) use 2 different networks on the same LAN/vLAN. From what I tried and understood : Host in network A (ex: 10.1.1.0/24) can talk to each ...
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2answers
2k views

Cisco: Storm Control not filtering packets on trunking port

We have an unknown device causing broadcast storms on the network. I have applied storm control to ever single access port in the location, and yet the broadcast storm exists. I was wondering if I ...
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3answers
2k views

Is it possible to assign network and broadcast addresses to hosts in the same network?

I know that it's not recommended to assign the network and broadcast addresses to a host but is there any way/hack using which you can assign them?
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1answer
595 views

What are the number of adjacencies in 10 router in mesh topology and DR/BDR topology in OSPF? [closed]

FYI: this is not a homework question. I was reading an article (http://packetlife.net/blog/2008/jun/19/ospf-network-types/) in OSPF and couldn't understand this point. "a segment containing ten ...
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2answers
774 views

Understanding Broadcast address

Please validate my understanding for the following points with regard to broadcast address: 1.Broadcast address is relative to a network, so every n/w will have it's own broadcast adress(I can obtain ...
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1answer
4k views

What is the Destination Address? [duplicate]

I have some doubt in the problem which follows: Suppose a host with IP address 19.121.202.123 wants to send a packet to all the hosts in the same network. Then, what destination address should it use?...
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How does router prevent Broadcast radiation

I just learned networking and according to a wiki article on broadcast radiation prevention, it says: Filtering broadcasts by Layer 3 equipment, typically routers (and even switches that employ ...
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80 views

How and what decides how many replicated packets need to be created in broadcast?

It just came across my mind that if I am broadcasting a message in my network, is it my computer, router or another node that decides to replicate the message? Also, how does that node how many times ...
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2answers
118 views

Questions about ARP

Windows homelab LAN: How come arp -d does not work consistently? I run the command and the ARP table is not cleared, yet when I run it again a few moments later it does work but leaves certain ...
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1answer
692 views

Router and broadcast domains

I am studying up for CCENT, and I'm having some trouble understanding what a basic router does. I understand one of the main functions is to split up broadcast domains. When they say it splits ...
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1answer
339 views

Broadcast packet in LAN is first sent to router?

Can you confirm that if host 1 wants to send a broadcast packet, he will send it to the router first, and the router will send it to all machines to the LAN ? I need to clarify this point in order ...
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2answers
523 views

Seeing traffic not addressed to me using tcpdump, how does that work?

I did a tcpdump capture, and when inspecting the reults, I saw some data I couldn't understand. Say the hostname of the box I did the capture on was box1.blah I saw traffic like this: box2.blah:...
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1answer
840 views

How does exactly reverse-path broadcast work?

I am not sure if I can ask this question on this website, since this is my first question here and I am not familiar with the kind of questions that can be asked here, but it is about a routing ...
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2answers
14k views

Technical difference between a Collision and Broadcast Domain

Many people new to networking wonder what the technical differences between a broadcast domain and a collision domain are. Specifically: What criteria is used to know the boundaries of a collision ...
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1answer
556 views

Spoofing Ethernet with Source as Broadcast

I was wondering the following: Assume I am attached to a switch with an Ethernet Cable and I try to spoof the source/origin MAC address of an Ethernet frame with FF:FF:FF:FF:FF:FF. How would it behave?...
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2answers
3k views

Scan all ip address on a network ARP/Ping

I'm working on a program to discover all computer on a network. What is the best way to do that My network is 192.168.1.0 There are few machines on this network and i want to know their ips Should i ...
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2answers
4k views

Do broadcast (FF:FF:FF:FF:FF:FF) packets go through the router, or directly all computers on the subnet?

If you have the destination MAC address you need in your ARP cache, surely it shouldn't have to go through the router? Or is that the point - only the router can be sure to have all of its subnet's ...
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1answer
390 views

force client to send broadcast packet

I have WiFi mesh network with more than one AP. So I want to see the clients' RSSI level for each APs to steer them to AP with better RSSI. I am curious whether I can check the RSSI by forcing them to ...
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1answer
567 views

How does a router/switch handle a limited broadcast address (255.255.255.255)? [closed]

Consider, there is router R connected to switches A,B,C. Each switch is connected to 5 systems. If a system in switch A sends a limited broadcast, will it be broadcasted only to the systems under ...
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1answer
3k views

How to block broadcast packets EXITING a single switchport

I have a couple cheap external wireless APs that like to reboot themselves constantly if they get even a few broadcast packets (i am ~90% certain this is the cause, after some testing with wireshark ...
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1answer
4k views

Why should one server repeatedly ARP for the same host?

I am trying to use Wireshark to find the root cause of a particularly slow network, and started by examining Broadcast traffic. Not only does Broadcast traffic represent over 25% of total traffic (at ...
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1answer
6k views

Point-to-point vs unicast, and multiaccess vs multicast/broadcast?

From Tanenbaum's Computer Networks: Point-to-point links connect individual pairs of machines. To go from the source to the destination on a network made up of point-to-point links, short ...
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1answer
5k views

Cisco: broadcast and multicast storm control on distribution switches

I just got some already configured switches that are giving a lot of problems on the network with port shutdowns due to storm control policies. Finally after dumping the running-config. I've saw ...
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1answer
82 views

ARP request complexity squared?

Is it valid to say that the complexity of ARP requests in a broadcast domain increases squared to the number of participants, as in the worst case every participant wants to address every other ...
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1answer
674 views

Why does a sever's host automatically broadcast an ARP request after a server attempts to reply to a BOOTP request?

I realise BOOTP is a legacy system, but this is for my reading for my studies. Consider a client, C, that is bootstrapping itself. It sends a BOOTP request to the server—obviously because it does not ...
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1answer
263 views

broadcast packets snmp graph shape

I recently started using OpenNMS to monitor our LAN. I found this broadcast packets graph on several devices. I'm trying understand the consistency (shape) of these data. Most other graphs, for any ...
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2answers
852 views

Arping for local broadcast address

Given the local IP-network 10.173.128.0/24 I am looking at a wireshark and there is an ARP for 10.173.128.255. Why would a network client ever ARP for a broadcast address? Does this indicate a ...
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1answer
127 views

Losing data when broadcasting over switch

I set up a port based VLAN on the first few ports of a 10GbE switch for broadcasting a UDP data stream. The data stream should use maybe 1/4 of that bandwidth. The switch is a netgear M7100. The ...
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2answers
2k views

HP ProCurve Auto WOL MAC Address of offline devices

I'm attempting to build a system to Auto-WOL devices when plugged into HP ProCurve switches (2510G and 2530G models). This is on a completely flat network, no VLANs or subnet routing. If you'd like ...
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1answer
293 views

What does Round Trip Time / Transmission Time tell us?

To phrase it as it's phrased more commonly: What does RTT/T tell us? I've seen this formula - Transmission Efficiency - mentioned a lot when it comes to networks: β = RTT/T But what exactly does ...
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1answer
86 views

Valid broadcast and multicast addressing

The other day I ran across a piece of software configured to "multicast" using the address 255.5.6.7. While I've seen local broadcast (255.255.255.255) and "true" multicast (as defined in rfc5771), ...
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1answer
707 views

Identify gratuitous ARP

I want to identify a gratuitous ARP. Can I say: If sender IP address and target IP address equal, it's always a gratuitous ARP?
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1answer
15k views

RIP V2 multicasting looks as broadcasting at IP add 224.0.0.9

In RIPv1 the packets are broadcasted out all ports with dest. IP 255.255.255.255. In v2 they are multicasted with dest. IP 224.0.0.9. In Packet Tracer, this v2 packet is transmitted over all ...
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0answers
195 views

Is it possible to calculate the path loss in an UMTS system if the current HNB CPICH power and RSCP values are known?

Please let me further elaborate on my question: Let's say we have an HNB with 2 Watts of power allocated for the common pilot channel. This would mean that the radiated signal power at the HNB site (...
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4answers
643 views

Calculating link utilization during a broadcast storm

Assume 3 switches connected in a ring topology forming a loop. If STP is disabled, a single broadcast packet is going to create a broadcast storm. If i assume a broadcast packet size to be 100bytes ...
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1answer
14k views

Difference between local broadcast and directed broadcast [duplicate]

In a Class E IP address , in the first octet,255 is reserved and used as a local broadcast.What does the term "local" signify here?How does it differ from a directed broadcast?
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3answers
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Wake on LAN across VLANs in IPv6 network

In IPv4, if I want to send a magic packet to a workstation in another VLAN, I enable directed broadcasts in the remote VLAN and send it to the VLAN's broadcast address. This works great. In IPv6, I ...
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2answers
4k views

OSPF manual neighbor configuration requirement on NBMA network

Why are OSPF neighbors manually configured on NBMA networks even when you enabled it with the broadcast keyword in frame map statements? Example is NBMA point-to-multipoint access. Thanks.
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2answers
8k views

ARP Replies can they be Broadcast

I have been informed by certain networking professionals that ARP replies can and sometimes actually are broadcast packets instead of unicast. If and when would you use a broadcast ARP reply?
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1answer
3k views

What is this UDP 5002 broadcast?

I hope this is an appropriate place to ask this. I'm confused because it's a broadcast at Layer 2 but it's UDP inside a VLAN with a destination to a unicast address (Y.Y.Y.Y). I was just wondering ...

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