Questions tagged [network]

For questions about Networking that includes design, and use of a network, the physical cabling, hub, bridge, switch, router, and so forth. Anything in relation to networking and its technologies.

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21
votes
6answers
6k views

What stops someone from configuring their network with IP addresses they do not own?

Here's the scenario. I was picturing a university that bought a range of IP addresses. I think they'd still be inside a ISP (right?), but they'd have freedom to configure stuff the way they wanted. ...
21
votes
2answers
8k views

Is multicast on the public internet possible? And if yes: How?

Is it possible to use multicast on the public internet? If yes: How? Are special IP addresses required and where do you get them from?
17
votes
4answers
3k views

How is 8 bits sufficient for the TTL in an IP header?

The TTL (Time to Live) is an 8-bit field in the IPv4 header. It can take any value from 0 to 255. If this means that the packet can take a maximum of 255 hops (routers) on its way to its destination, ...
14
votes
1answer
14k views

How multiple client connections are made to single web server?

Actually I am learning Computer Networks and while at it, I am confused in how a web server maintains multiple connections? Simply to state, I learned trough some googling is that sockets handles a ...
13
votes
8answers
14k views

Does TCP open a new connection for every packet that is sent?

This might be a silly question but a me and few buddies have been discussing the potential limitations of TCP. We have an application that is going to listen for clients (think of a gateway) and route ...
13
votes
3answers
1k views

Where can I use the IPv6 documentation prefix

We are currently building a networking course with a practical part where students have to configure a small network in a virtual environment. However, we are not sure what ipv6 prefixes we can use ...
13
votes
6answers
3k views

Network latencies between opposite ends of the Earth

This is just out of curiosity. I'm currently in South-east asia, and when I pinged domains such as bbc.co.uk and google.com (in California), I get latencies of around 5ms as below: 64 bytes from 151....
11
votes
8answers
5k views

Why are IP addresses given to each interface and not device? What would the implications of that be?

Why do we need to give IP addresses to each interface? Wouldn't giving one to each device be enough?
10
votes
3answers
5k views

Difference between router and gateway

What is the exact difference between router and gateway? In Network configuration we set the default gateway ip address, but in reality we call the device configured with that ip address as router?
8
votes
5answers
2k views

Cascading Switches. Will it affect performance?

I am really new to large scale networking and all I know is the basics. I will be doing a network for a huge workspace consisting of multiple offices. There will be a total of 308 Clients, with at ...
8
votes
8answers
3k views

Can Ethernet frames only be transmitted in a LAN?

In the LAN depicted in the picture below, am I correct in saying that devices do not have IP addresses? There is no router and also only Ethernet frames (with source and destination mac address would ...
7
votes
7answers
3k views

How LAN works in video games if only one station is permitted to transmit?

I've read the in a LAN the data is transmitted in packets so as to allow only one station to transmit at a given time, so how could this be applied in video games LAN parties if only one device is ...
7
votes
2answers
980 views

Why do IPv6 unique local addresses have to have a /48 prefix?

According to RFC 4193, unique local addresses will always have a prefix of FD00::/8.. but according to Wikipedia: The block fd00::/8 is defined for /48 prefixes, formed by setting the forty least-...
7
votes
2answers
2k views

What is IP squat space

I came across this article and I'm trying to understand what is going on here, I found some packets on my network containing 22.0.0.0/8 and 29.0.0.0/8 IP range and It's based on: https://en.wikipedia....
7
votes
4answers
650 views

Abstract language to describe network deployments?

Is there any more or less standard/spec that is, vendor neutral, for network configuration language? Say, a VPC with networks and virtual machines would become an XML or JSON file. Something like, &...
7
votes
1answer
398 views

Cisco IOS Tcl - Overhead

I've not been able to find much in regards to TCL other than the Cisco PDF "Cisco IOS Scripting with TCL Configuration Guide" and I just have a few queries. I'm looking into potentially utilising ...
7
votes
2answers
2k views

Network Gateways vs Interfaces

When looking at the contents of a routing table section on the Wikipedia article on Routing Tables, it contains a table as an example of a routing table with two headings which have an unclear ...
7
votes
1answer
1k views

Raw API data for Cisco Meraki CMX Dashboard

Has anyone worked with Meraki's CMX raw data feed and can help answer some questions? I came here to ask because I have found no conversations about Meraki's CMX API elsewhere and I imagined that ...
6
votes
3answers
948 views

What is the characteristic of spoofed ARP packets?

Hi what is the characteristic of spoofed ARP packets? I want to know how to detect it but before that I have to know how can I call a packet a spoofed packet. I hope you can help me thank you.
6
votes
2answers
384 views

how to find the right value of MTU Jumbo frame

we take the decision to set jumbo frame on all our linux machines we have hadoop cluster with master machines , workers machines and kafka machines our switches ( Cisco ) are suitable to Jumbo frame ...
5
votes
5answers
187 views

How do two computers with different speeds communicate

This is one extremely basic and probably equally dumb question that I just couldn't ever find a definite answer to. Suppose we have 2 computers one that can transmit data at say 10 bits per second (A)...
5
votes
4answers
186 views

Packet Collison Avoidance

If a wireless network has collision avoidance, how comes the network slows down if more clients connect to it?
5
votes
3answers
1k views

Need help understanding how packets travel across the internet

I've been learning about networks recently at a new job, and I did a presentation on what I've learnt so far. When I was describing the relationship between the datalink and network layer, I mentioned ...
5
votes
3answers
868 views

Cables on a closed rack

I've just spent the last few days building my first server rack. It will be a significant upgrade to our current mess. I was asked to buy and install one and so I did. I was not completely aware of ...
5
votes
2answers
1k views

Layer3 vs Layer2 LACP

We have ISP link 4x10G LACP Layer2 and now we are upgrade to to 8x10G LACP, currently i have created VLAN interface to terminate that link because it L2 Now i have option to decide to go with L3 or ...
5
votes
2answers
64 views

Network Switch Power Isolation

I run a small office network that uses TP-LINK T1600G-28TS (TL-SG2424) JetStream switches. The office is across two buildings, each fed by a different phase of power. We've recently installed HD ...
5
votes
1answer
631 views

Router benefits in 2018 compared to a L3 Switch

What are the benefits nowadays to use a Router instead of a L3 Switch ?
5
votes
1answer
1k views

Cisco HSRP CAM vs ARP timeout

Today we received email from our ISP saying they are performing maintenance on their network so if you have HSRP connectivity with them in that case you need to clear ARP table or reduce ARP timeout ...
5
votes
1answer
5k views

What is the use of the IPv6 scope ID?

In the structure struct sockaddr_in6, the field sin6_scope_id is declared. What is the use of this member? How can we know from the IPv6 address and the prefix length the scope that it should use?
5
votes
1answer
5k views

Do i need to configure VLANS on my router/firewall or just the switch?

I finally took time to map my entire shitty network to understand exactly what the guy before me did, and i must admit i'm a little bit surprised even if i'm not a network expert... Just take a look ...
4
votes
2answers
2k views

Why we use 224 as multicast address in many protocols?

I see in many protocols we use 224 multicast address as like eigrp uses 224.0.0.10 ospf uses 224.0.0.5 224.0.0.6
4
votes
3answers
2k views

What does the “T” shape mean in network topology?

What does the "T" shape mean here? There is a logogram, but I want to know the RTA's left side port whether is config the 192.168.1.0/24 network segment's IP address. This is Quidway technology.
4
votes
3answers
425 views

Is there any reason to use a hub over a switch?

Given that hubs are essentially the same as switches, as far as I know, except they share bandwidth between all connected devices, while switches do not, resulting in faster connections. I am simply ...
4
votes
3answers
255 views

Leaf-Spine network without routing

If I have a leaf-spine network with all the servers on the same subnet, say 10.10.0.0/16, do I need a router (or l3) since everything is on the same network and the network is flat?
4
votes
2answers
3k views

The best way to understand Vlans?

Every time i try reading about the configuration of a device and adding it to the network, i always face a problem. The problem is basically am not able to understand Vlan's, and how for example some ...
4
votes
3answers
1k views

Error Detection across OSI layers confusion

Confusion: How does the transmitter know that his information( bits in physical layer, frames in data link layer, packet in network layer ) was transmitted correctly to the receiver? I know that in ...
4
votes
1answer
120 views

Ingress filtering on edge routers and performance concerns

The RFC 4778 cover the Operational Security Practices in ISPs Environments back on 2007. Among the best practices, a common one is Ingress Filtering on edge routers. In the above RFC, the author says ...
4
votes
2answers
462 views

Unbundling local loop

When we are dealing with local loop, we indicate the last mile of connection from the CABINET (or whatever else) to the subscriber. Now, I'm asking to you, the local loop is the medium of the access ...
4
votes
2answers
289 views

Destination device disconnects while packet was in transit

What happens when the original destination IP address of a packet was reassigned to some other device(if the original device disconnects) while the packet was in transit?
4
votes
1answer
773 views

Should a Metropolitan Area Network (MAN) be setup with a router at each site?

Should a Metropolitan Area Network (MAN) be setup with a router at each site? Or, because the connections between sites are usually at layer two, should each site operate on one "master" switch which ...
4
votes
2answers
89 views

Whether we usual use dot-decimal notation to represent network or IP by opposite mask?

Whether we usual use dot-decimal notation to represent network or IP by opposite mask? 10.10.10.0 0.0.0.255 # a network 10.10.10.0 255.255.255.0 # a IP Update if we represent a network, we can use ...
4
votes
1answer
41 views

F5 BigIQ communication with BigIP

I'm new to F5. Basically a BigIQ centrally manages BigIP load balancers. In order to update the device, I have to login to the UI and apply the changes there. I would like to know how this is done (...
4
votes
1answer
520 views

Is the fact that cable internet access is a shared medium intrinsic to its HFC infrastructure?

I know that cable ISPs use HFC, while DSL uses classic twisted pair. Is the shared medium an intrinsic side effect of a coaxial cable? Couldn't you set up a twisted pair infrastructure to also be a ...
4
votes
3answers
718 views

Need for network layer

I was reading about the 'IP' in TCP/IP. Most of its functions seem to be for connecting different (types of) networks. Does this mean that network layer is not required for communication between ...
4
votes
2answers
467 views

How does NAT table response when there are no open ports?

I'll be glad to hear what really happens if the router has no open ports, for example if there is a big network and every computer sent a lot of requests and the server is slow so the table's ports ...
4
votes
1answer
90 views

OSPF - networks/links don't get advertised

In my Multiarea-OSPF configuration I can ping my neighbor, but nobody which is more than one hop away (for instance ABR2). Also traceroute just shows "1 * * * - 2 * * * - 3 * * *" Can ...
4
votes
0answers
54 views

Cisco nexus 9396 rebooted with reason xbar_client

Today my one of cisco nexus 9396PX switch got rebooted and this is what i found, based on following logs what could be wrong? We don't have Cisco support for this switch, trying to see if i can get ...
3
votes
2answers
877 views

Does it make sense to map a VLAN to each LAN?

I saw a picture of a network-structure with VLANs in it: Why would somebody structure their network like this? Does this even make sense? I mean, they are in a different LAN, why then mapping a VLAN ...
3
votes
2answers
259 views

Cannot see the differende between distance-vector and link-state

At link-state routing protocols each router advertises every link he knows about to the next router, which again advertises his links and so on until every router knows all links in his area. So every ...
3
votes
2answers
86 views

Why can't I get a WiFi password by sending out the same SSID?

If I have two WiFi routers in different locations but with the same SSIDs and I connect a device to one of them, when I bring this device near the location of the other router, it will automatically ...