Questions tagged [ip]

For questions about Internet Protocol (IP), an OSI layer-3 network protocol. There are two current IP versions in use: IPv4 and IPv6.

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Does the MSS (Maximum Segment Size) prevents IP Fragmentation in all cases?

I have read that the MSS (Maximum Segment Size) is used to prevent IP Fragmentation. Now if the two communicating devices exist on the same network, and this network have a MTU (Maximum Transmission ...
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question about the router [closed]

as i understood, the router has at least two network interface(LAN,WAN),the ip of LAN is private,and the ip of WAN is public -does the ip address of WAN interface in my router is my public ip? -and ...
1 vote
1 answer
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What does "direct-attached networks" mean?

This page says the following: TCP controls this maximum size, known as Maximum Segment Size (MSS), for each TCP connection. For direct-attached networks, TCP computes the MSS by using the MTU size of ...
2 votes
2 answers
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Can you send data in LAN without an IP?

From What I know, IPs are used to communicate b/w two different networks say LAN1 and LAN2... and MACs are used to communicate within a LAN.. I think this because my instructor says that Hubs and ...
4 votes
1 answer
162 views

Does the IP header have a "Padding" field?

I found two images of the IP header, one image shows a field called "Padding", while the other image don't show the "Padding" field: Which one of these two images is correct?
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2 answers
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IP packet expired by TTL generate an ICMP response in any case?

Acording to Wikipedia IPv4 article for TTL header field: An eight-bit time to live field limits a datagram's lifetime to prevent network failure in the event of a routing loop. It is specified in ...
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HOW TO MAKE 2 IPS ON DIFFERENT SUBNET COMMUNICATE [closed]

I am kind of new to networking so pardon me if my question looks trivial. I am trying to make 2 LANs communicate. My infrastructure is simple, we have an ISP router => Fortinet 300E (which also ...
3 votes
2 answers
2k views

What this subnetting restriction means

I was reading Data Communication book by Forouzan in which there is a one restriction put on CIDR subnetting by Internet authorities: First IP address in the block should be evenly divisible by the ...
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Tcp/Ip to OSI model [duplicate]

The universal standard of communication using the TCP/IP is this: Now comparing it to the OSI model,can we conclude that the Internet layer is the Network layer in the OSI model and the Link layer is ...
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Why we need MAC address when transferring if we have static IP? [duplicate]

I just wanted to know if h1 and h2 have static ip and we want to transfer some file, so why we need to use mac address? Are not static ip addresses enough for this ?
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1 answer
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Packet tracer help with routing between multiple company routers with vlans and wireless routers

Im still quite a novice to packet tracer (so im sorry if this has been answered) and I'm trying to ping both vlans at company1 router to both Lans at company2 router but for some reason when the ...
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1 answer
1k views

How to Run Static IP Through Comcast Business Class Modem to Router?

I apologize in advance for this kind of nebulous question, but I'm very stuck after many hours of trying and I need help. Here's what I have: Newest model of the Comcast Business Class Modem/Router ...
1 vote
1 answer
264 views

How CIDR helped to slow down routing table growth?

Besides allowing for a greater number of ip addressed, Classless Interdomain Routing (CIDR) was also intended to slowdown routing table growth in core routers.[1] I may understand how it expands the ...
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3 answers
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How to use IP pool

I am just beginner, I just want to setup my mini data center and for testing i get a FTTH connection and /30 ip pool, ISP reply is something like that, "IP Pool 103.15.xx.xx/30 has been assigned ...
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1 answer
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Relation between the BACnet 4 layers and the TCP/IP 5 layers

How are the BACnet 4 layers (physical, data link, network, application), related to the TCP/IP 5 layers (physical, data link, network, transport, application)? Are they separate of them, or build on ...
19 votes
9 answers
12k 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?
2 votes
2 answers
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How does Network Layer behave when client received a unicast DHCP offer?

I went through various stack exchange post to understand the concept of DHCP offer when it comes as a unicast to client from the DHCP server. A server can send a unicast DHCP offer since it knows the ...
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What is the difference between a private IP and a MAC address? [duplicate]

I am taking a course preparing me for the Network+ certification. I wanted to know what the purpose of a private IP is when a MAC address exists. From what I understand, the MAC address is used to ...
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How are we still able to use IPv4 address even with NAT? [duplicate]

My question is why haven't we run out of IPv4 public IP as well because now almost all home has a router which is assigned a public IP. Is it possible to have multiple layers of NAT on the router-ISP ...
6 votes
1 answer
201 views

What's the domain of an IP?

CIDR stands for "Classless Inter-Domain Routing". But what's a domain in this case? Seems to not be the same kind of domain as DNS deals with...
2 votes
0 answers
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How lsp-ping works with php in picture?

If my understanding is correct, lsp-ping will have destination IP addresses set to loopback address(127.0.0.x), to force the label switching of the packet and thus checking the LSP connectivity. When ...
2 votes
2 answers
68 views

Loops in routers-same packet?

Considering a loop topology between a few routers with a host connected to one of them, when it's default routing directs to the cycle. Even when observing Wireshark, how can we know its the same ...
1 vote
2 answers
94 views

What should we do if the number of bytes to be transferred are not in multiples of eight in ipv4? [duplicate]

(it is take from book called special edition tcp ip, pic taken for better formatting and ease to read) Theory that I am trying to understand-: So i found a question that is relevant to this-: ->a ...
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1 answer
22 views

Constraint on length of message & segment to be integral number of bytes, as mentioned in Cerf & Kahn's Paper

I have a question about the below excerpt from Cerf, V.; Kahn, R. (1974). "A Protocol for Packet Network Intercommunication". IEEE Transactions on Communications. 22 (5): 637–648. ... ...
24 votes
7 answers
9k views

Does CIDR really "do away" with IP address classes?

I am still struggling to understand to what extent CIDR really renders IP address classes obsolete. Here's what I understood so far: It's ridiculously inefficient (and impossible, too) to assign ...
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How many /56's are there in a /49 IPv6 [duplicate]

I am studying subnetting in IPv6. I came across the following question from a website called Subnetting Practice, which I will quote below. How many /56s are there in a /49? Could someone please ...
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2 answers
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Simple IPv6 Global Unicast question

I was reading this article which states: RFC 3587 states that out of the 128 bits in IPv6 addresses, left most three bits are must be fixed as 001. Remaining 45 bits are reserved for global routing ...
1 vote
1 answer
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How is 65535 bytes is total length of IP datagram?

The maximum size of an IPv4 packet is 65,535 because the Total Length field is a 16-bit unsigned integer, which has a possible 65,536 values (from 0 to 65,535). This created 2 confusions for me. Say ...
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1 answer
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What are the IP/MAC addresses of requests between 2 different subnets? [closed]

Assume that networks 172.15.10.0/24 and 172.15.11.0/24 are connected through a router with interfaces 172.15.10.254 (MAC3) and 172.15.11.253 (MAC4). If host A sends a packet through its network ...
8 votes
1 answer
1k views

What does it mean to “plumb” an IP address?

Plumbing an IP address means what? What are some examples of it?
1 vote
2 answers
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Why shortened version of IP4 exists and it is undocumented but supported everywhere?

For example there is an IP address 192.168.0.1 It is clear that you can use it as the full line, but try that one 192.168.1 It will also work, and it will be automatically converted to 192.168.0.1 ...
0 votes
1 answer
28 views

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 ...
2 votes
3 answers
6k views

What is the relationship between the IP address and MAC address?

I own a MAC address and I want to know from it, the IP address.
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2 answers
112 views

Why in the TCP/IP model the link & physical are one?

I'm currently learning about the OSI model and the TCP/IP models, and I was wondering: Why in the TCP/IP model the physical layer and the data link layer are combined? I'll state how I understand the ...
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3 answers
5k views

Why there is only one hop in the tracert?

I use the tracert to a remote server IP address: C:\Users\lll>tracert 103.224.19.11 Track by up to 30 hops The route to f1.FF-SALE.COM [103.224.19.11]:    1 44 ms 44 ms 44 ms f1.FF-SALE.COM [103....
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1 answer
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Why is this 254.63.0.1, not a valid host address?

Getting the below error, when trying to configure the ip address 254.63.0.1 as an SVI. Switch(config)#interface vlan 254 Switch(config-if)#ip address 254.63.0.1 255.255.0.0 Not a valid host address -...
1 vote
3 answers
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Why the host part of a Mask is 254 (256-2) instead of 253?

Don't hate me for being such a newbie but I'm so confused. If we have 32 bits, each octet adds up to 255, why the host part is 254 (in a 255.255.255.0 mask) instead of 255 - 2 ? Thanks so much for ...
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How IP packet's payload bigger than the whole former PDU (segment)? [duplicate]

As far as I know: File is too big ---> Fourth layer (TCP or UDP) divide it to a multiple segments ---> Then each segment encapsulated separately into a packet. What means if I have 10 segments, ...
1 vote
1 answer
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How does a computer determine that an Ethernet frame contains an IP packet? [duplicate]

So far as I can tell, there is no "Next Protocol" ID at the Ethernet / data link layer. Nor do IP packets seem to contain any magic numbers for identification purposes. Does the OS bind each ...
0 votes
1 answer
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Inherent flaw in stateless firewalls?

I am but a lowly (software) developer dabbling with setting up a network in AWS and am having trouble understanding the fundamentals of stateless firewalls, or Network ACLs as they're also referred to ...
2 votes
1 answer
80 views

Custom option in IP header

I would like to add (or piggyback on an existing not used) a custom option to the IP header. I've full control of the IP stack at both end points, but I've no control on all the hops in the route (...
0 votes
0 answers
7 views

Dividing network into subnets [duplicate]

My teacher uploaded this example question and solution as explanation of the topic: I watched some videos about it but none of them made it fully clear, what I don't understand here is: What are ...
3 votes
1 answer
52 views

How are IP broadcasts handled at lower levels

When I use a broadcast IP address, for example 198.255.255.255, what will happen when it gets passed down to the link-layer which will then look for the corresponding MAC address in your ARP table. ...
5 votes
4 answers
12k views

Network setup for multiple devices with the same IP

Because I do not find the correct question that I can ask google, due to the lack of terminology. I'm trying to ask it here. Please have patience. My Question is similar to the questions asked here ...
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3 answers
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why ip adresses are divided into network portion and host portion when we already have NAT [duplicate]

I don't understand why ip adresses are divided into network portion and host portion? is the host portion really necessary when we already have NAT? for example, if ip addresses only have network ...
3 votes
2 answers
293 views

Why can IPv4 and IPv6 use strict source routing(in options field) and flow label respectively inspite of connectionless protocol?

In IPv4 option field one field option is source routing option this means packet will always be routed by router Or not. Packet can also be routed by source such routing is known as source routing. ...
8 votes
3 answers
8k views

Usage of Flow label in IPv6 header?

I have been reading the IPv6 Flow Label Specification (RFC 6437) and I would like to ask about the purpose of setting this label. In case of just using the 2-tuple (source address, destination address)...
129 votes
6 answers
805k views

How do you calculate the prefix, network, subnet, and host numbers?

Example: IP: 128.42.5.4 In binary: 10000000 00101010 00000101 00000100 Subnet: 255.255.248.0 How could you determine the prefix, network, subnet, and host numbers?
7 votes
7 answers
3k views

Why is classful addressing considered waste?

I am trying to understand the addressing strategies. But there is something which I can't grasp. Maybe I am missing a very basic point, if so, I am sorry beforehand. From my researches, let's say, if ...
0 votes
1 answer
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point-to-point at IP layer

I was reading one of 5G standards specifying signalling transport https://www.etsi.org/deliver/etsi_ts/138400_138499/138472/15.06.00_60/ts_138472v150600p.pdf and noticed (section 6): The IP layer of ...

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