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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DHCP Discover Broadcast and its IP (255.255.255) [duplicate]

Cheers, I am trying to learn more about DHCP, and when studying about the session that DHCP goes through every one mentions that it broadcasts a discover message at IP: (255.255.255.255) (as seen here ...
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BACnet broadcasts with 2 subnets on one VLAN

I have a building automation network configuration with mechanical equipment on subnet 10.233.138.0/24 and electrical equipment on subnet 10.233.136.0/23. BACnet uses broadcasts for certain functions ...
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3 votes
2 answers
193 views

Can Directed Broadcasts be forwarded even if the destination is 2 hops away?

I was studying for the CCNA exam and I read this: " When a directed broadcast packet reaches a router that is directly connected to the destination network , that packet is broadcast on the ...
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broadcast instead of multicast for CARP/VRRP/keepalive

In many cloud environments, multicast is blocked therefore when trying to configure CARP/VRRP customer needs to add a dedicated switch. For example, CARP partially works if using a vSwitch from Hetzer,...
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Optimize Network For UDP Broadcast Traffic?

I have a computer that creates an AP which multiple microcontrollers connect to. The computer sends out UDP Broadcast packets that tell the microcontrollers to do different things. I have an issue ...
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How does a network switch prioritize ethernet frames with the broadcast MAC address?

How does a network switch prioritize the incoming ethernet frames that all have the broadcast MAC address as a receiver address? So, we have the following situation: a 10GE network switch with 3 ...
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How does a router handle a directed broadcast on the same network?

I have started reading on Computer Networks recently(beginner), and have come across some of the doubts regarding how the broadcasting is handled by routers and switches. Assuming there are no ...
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L3 switching and broadcast

I don’t know is this the right way to ask this question. But anyway my question is when we configure L3 switchport as a routed port and it’s connected to a another L3 switch. Does that routed port ...
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Broadcast over all internet

Is it possible for someone to send an IP broadcast packet over all internet? I know that routers do not allow that, but is there any other way?
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issue regarding broadcast mac address

I read a line saying {Routes do not forward packets coming from one interface having broadcast mac address (FF:FF:FF:FF:FF:FF)} what is meant by one interface in that line? if router cannot broadcast ...
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WiFi AP mode. Is AP bradcasting SSID all the time or when it receives the request from the station

WiFi AP mode. Is AP bradcasting SSID all the time or only when it receives the request from the station? I cant find the answer and maybe someone of you guys know the answer.
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How do I set a display filter in wireshark that sorts by destination broadcast?

1 0.000000 Vmware_90:07:7b Broadcast ARP 60 Who has 192.168.185.144? Tell 192.168.185.7 27 0.995837 28.144.7.123 192.168.185.144 HTTP 1177 HTTP/1.1 200 OK (...
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Can modern network equipment handle very large broadcast domains

We operate a network where we have 'tons' of VM servers that are physically hosted on many many blade chassis. The thought behind the original design was to simply put them in one very large ...
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2 votes
2 answers
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MAC address and unicast, multicast and broadcast

I'm very new to computer networking and I'm trying to figure out this dilemma about the Unicast, Multicast and Broadcast transmissions. I was told that MAC address are unique for each device and they ...
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Issue with PIM-SSM Multicast Configuration ISR4431s

I have an issue with my PIM-SSM multicast configuration using ISR4431s.    I am wanting to forward broadcast data from an application from one VLAN in on the multicast source to another VLAN on a ...
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Sending a gratuitous ARP on an interval - Cisco

In response to my question Propagating Static MAC Addresses , I realize I can not avoid the unknown unicast problem. Essentially I have hosts that forward their traffic via an L2 frame to a ...
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Juniper MX: NTP broadcast on two VRFs with the same addressing

In Juniper, NTP broadcast is set at system level, so two VRFs cannot use the same addressing and use NTP broadcast at the same time. Is there any alternative?
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Unknown DHCP problem

Sometimes in my network I have some DHCP problem, the clients don't receive their IP. The problem seems connected with the switch because, for example, if I change the switch port of the client the ...
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Broadcast ICMP and gratuitous ARP

When sending an ICMP broadcast, all nodes can respond. is it the case of the sender too? If it's the case then: Is it specified somewhere that the sender should respond with gratuitous ARP when the ...
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WHY and HOW do routers and vlans break broadcast domains?

Everybody says routers (and vlans) break broadcast domains, but nobody goes into WHY that is, it seems. What's the router logic? Say I have three routers on my lan, with one main router and the ...
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Are network IP addresses ever used as source or destination IPs? [duplicate]

The first IP address of an IP subnet is the network address, which stands for the whole network, while the last address is the broadcast address. As far as I understand, we never really send packets ...
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Will DHCPRequest get ignored by other computers?

I've been reading about DHCP and see that it uses limited broadcast to send its initial request to reach a DHCP server. I read about limited broadcast too which says it sends the message to every ...
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Broadcasting to unknown Class C Network

I am trying to use python to broadcast to my local network, and I cannot find a way to get the subnet mask. I have been suggested to use the default Class C network subnet mask 255.255.255.0, and use ...
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2 answers
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Where are broadcast packages filtered out

When I have one network with a switch. Within that network I have 10 PC. Halve of them are configured within the 192.168.1.0/24 range and the other halve is configured at 192.168.2.0/24. This means I ...
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2 votes
1 answer
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Is an IP broadcast always a layer 2 broadcast also

On my PC I see 255.255.255.255 in ARP with MAC FF:FF:FF:FF:FF:FF, so I'm assuming that in most cases the L3 broadcast is also encapsulated into an L2 broadcast frame, but is this standardized? For a ...
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How to calculate subnet mask including, network address, gateway, broadcast address and host range? [duplicate]

You are defining network boundaries within a /24 network of 172.30.20.0/24. Please complete the segmentation of the /24 to account for multiple smaller networks of 115, 50, 28, 12, and 5 hosts. ...
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Wake-On-Lan (WOL) from WAN does not work with Unifi (USG/Switch)

tl;dr I need WOL over the internet over the USG to work. WOL works already locally. I guess the USG/Switch is the problem. Hi all As a newcomer to networking in general and Unifi in particular I am ...
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16 votes
4 answers
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Why is 10.1.255.255 an invalid broadcast address?

I’ve been following the CCENT official certification book(100-105) and came upon this question in the “do I know this already?” quiz. The books only covered /24 subnetting only so far. Which of the ...
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5 votes
1 answer
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Getting lot of unwanted broadcasts on my network

I am pretty new in Networking (noob), while I was monitoring my network using Wireshark, and I found that there is a lot of broadcasts happening all over the network, broadcast on Local network ...
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How the broadcast MAC address accomplished?

The Layer 2 broadcast is the destination address of the Layer 2 package is FF-FF-FF-FF-FF-FF. I have a question about the broadcast MAC address. you see the ARP request, it send the destination MAC ...
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1 vote
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Will this network diagram cause broadcast storms?

I have three VLANs, and I want to communicate between them, but all packets are dropped. I made a trunk to allow all VLANs. Should I use STP to control broadcast storms?
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ccna: Collision domain vs broadcast domain [closed]

I am currently preparing for CCNA I have a screenshot of CCNA online test. I don't remember if I got it right or not. I think there are 2 broadcast domain (circle with hand on the picture) and 5 ...
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2 votes
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very strange broadcast in LAN with Cisco ASA

Today i have detected Cisco ASA 5505 CPU usage went to 100% and LAN was flood with broadcast (ff:ff:ff:ff:ff) going to 10.0.12.255 address, i have noticed all these activity in wireshark that some ...
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-1 votes
2 answers
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is it ideal for a network that abandon the use of L2 switch?

I'm thinking about minimizing network hardware while optimizing network topology for company. If a company has unlimited(or very high) budget to build an ideal network for internal use(traditional ...
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1 vote
1 answer
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Sending Broadcasting Frames after sending Unicast Frames

Absolute newbie here guys, I was reading the compTIA Network+ guide by Mike Meyers, and a section reads: "The frame propagates down the wire into the central box. The switch sends unicast frames to ...
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3 votes
3 answers
13k views

Do routers forward broadcast traffic?

Consider a host on 10.0.0.0/24 sending a packet to 10.0.0.255 and 10.255.255.255. In the first case all hosts on his subnet should recieve the packets but would the entire network receive the packet ...
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Hierarchical issue of Broadcasting on different subnets

I've got a problem that I can't seem to understand. 192.168.255.0 /24 is a valid network address. The broadcast address for this network is 192.168.255.255. 192.168.0.0 /16 is a valid network ...
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1 vote
1 answer
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Flooding vs Unknown Unicast Flooding

Can someone clarify what is the difference between Flooding and Unknown Unicast Flooding? Is it the same thing or it contains different meaning? I'm aware that Flooding happens when a switch ...
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1 vote
1 answer
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Permit IP Directed Broadcast on DELL FTOS

OK so in cisco land you can add an acl to the ip directed broadcas command, but this option does not appear in FTOS (Dell Networking OS 9) if you enable ip directed broadcast on the vlan and then ...
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2 votes
1 answer
668 views

Defining what type of casting based on IPv4 address

I'm kinda new to networking. I have a small question, how can I determine what type of casting (unicast, multicast or broadcast) is it based on IPv4 address. For example: 142.55.172.200 I tried to ...
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1 vote
1 answer
179 views

Dhcp Broadcast Through Switches

Think of a pc connected to switch1. Sw1 is connected to sw2(trunk port on both switches) and sw2 is connected to a router(dhcp server). Pc sends a dhcp broadcast. Does sw1 passes the broadcast through ...
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1 answer
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DHCP Broadcast on SVI

Think of a dhcp broadcast going through multiple switches. What happens to that broadcast when it reaches the vlan interface (svi)?
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2 votes
1 answer
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Broadcast domains switches

If I connect 3 computers to the same switch and used one of the PC's to ping another PC on the switch will this cause a broadcast domain as they are connected to the same switch?
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1 vote
1 answer
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What practical concerns led to the use of multicast?

Answers to a question on SF explain the differences between broadcast and multicast. It is not clear yet for me which practical concerns brought in the usage of multicast. My understanding is that, ...
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3 votes
1 answer
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Ability to monitor all broadcast domains

Example: Network of company A has 5 VLANs: Accounting, IT, Guests, Servers, Board. All VLANs has DHCP servers enabled in their own VLANs. I am monitoring a single VLAN for DHCP packets by connecting ...
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2 votes
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Do the intermediate nodes learn a MAC address in ARP?

my doubt is about the ARP protocol. I know the procedure: if a host wants to know the MAC address of another sends a broadcast frame and the destination answers with its MAC. However, if an ...
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What happen if broadcast is made to first and last address of other network?

Broadcast to network id What happens if you broadcast to the first IP of another network ? broadcast to broadcast id of another network What happens if you broadcast to the last IP of another ...
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2 votes
1 answer
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Network discovery and establishing connections within Eduroam, a network split in subnets

For our current project we are supposed to create a peer2peer (no server) game application which is played by a teacher and his students on the Eduroam network. The concerns of the stakeholder ...
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9 votes
2 answers
754 views

How to control unwanted UDP traffic (Broadcast & Multicast) on Cisco Router 2911?

Please suggest, we are getting UDP traffic either broadcast or multicast in router 2911 which cause 95%+ utilisation of the router. And we got error in link and business impact due to this. Company ...
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7 votes
2 answers
763 views

How is the Groupwise Transient Key used in WiFi networks?

In Wifi WPA, I understand that during association, a 802.11 client and AP negotiate a Pairwise Transient Key (PTK), using which the Groupwise Transient Key(GTK) is provided to the station. I ...
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