Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

0
votes
1answer
156 views

IP packet reading

Just got an simple question.Its abt reading a plane IP packet. In a standard IP packet RFC 791, there are multiple fields, the IP packet header size is 20 bytes. Now when i look at following packet ...
0
votes
1answer
887 views

Internet Protocol error checking

The RFC 791 says : The internet protocol does not provide a reliable communication facility. There are no acknowledgments either end-to-end or hop-by-hop. There is no error control for ...
6
votes
4answers
768 views

OSI layer of Neighbor Discovery Protocol

NDP operates using ICMPv6 and, even though ICMPv6 messages are encapsulated in payload field of IPv6 datagram, ICMPv6 and ICMP are usually considered as network layer protocols. At least, on Wikipedia ...
0
votes
1answer
23 views

Daisy chaining IOT devices without switches? [closed]

I have multiple IoT board with two network interface in each device. I want to connect them in a daisy chain without help of switch. The eth1 of first device will be connected to eth0 of second device,...
9
votes
2answers
765 views

ipv6 Aggregatable global unicast addresses

Studying IPv6 addressing I haven't understood IPv6 aggregable global unicast addresses, I mean on RFC 4291 there is a generic scheme: | n bits | m bits | 128-n-m bits ...
1
vote
1answer
168 views

How do ICMP packets travel in a networks?

Questions: I'd like to know how ICMP packets travel in a network? Are they encapsulated within IP datagram? The RFC 792 doesn't explicitly states the layer of ICMP. Are ICMP messages sent using a ...
12
votes
3answers
29k views

How broadcasting works on different networks?

I was reading DHCP ( RFC 2131 ), I have basic knowledge about Relay Agent and Broadcasting. But for Understanding DHCP in depth, I felt like I have to know Broadcasting and Relay Agent ( RFC 1542 ) in ...
2
votes
1answer
349 views

Internet Protocol. Source Routing. RFC 791. Are the addresses in the Source Routing option 1-indexed?

I was reading pages 18-21 in RFC 791 about the Internet Protocol and in the sections on Loose Source and Record Route (LSRR), and Strict Source and Record Route (SSRR), and Record Route (RR) it says ...
2
votes
1answer
32 views

Global Unicast in IPv6 Neighbor Discovery

I have a very small pcap file in which Neighbor Discovery is performed for Global Unicast Addresses. That is, IPv6 addresses of both neighbors as I can see in Wireshark start from 2001:. Both IPv6 ...
3
votes
1answer
202 views

Basic questions about Public IP addresses and used ports

I realized that all of my devices have the same public IP address (I had knowledge about the concept of public and private IP addresses, but I thought this was unique in both cases), so what I do not ...
6
votes
1answer
2k views

Why is the NDP Neighbor Solicitation message sent to the solicited-node address?

As I understand it, when Host Alice knows Host Bob's IPv6 address but not its MAC, Alice sends an NDP Neighbor Solicitation (NS) message to the solicited-node multicast address for Bob. Alice knows ...
3
votes
1answer
423 views

Is there any way to check if an IP address is a real IP address or private IP address?

Is there any way to check if an IP address is a real IP address or private IP address?
1
vote
1answer
2k views

Cisco Packet Tracer (overlap error)

Last time i had many mistakes this time the problem is on in the cardif but i dont get it i do the math and the resuls are right.
1
vote
2answers
180 views

Link Local Address using in NDP (IPv6)

How is using of link local address in NDP. We can discover neighbor by using global address. So why we need link local address in NDP?
19
votes
1answer
3k views

What is the practical use of a /31 CIDR or 255.255.255.254?

With a /31 subnet, we are left with zero usable hosts. The /31 subnet only has two hosts - one for network and another for broadcast. I am wondering why would someone ever use this subnet.
3
votes
1answer
2k views

Understanding the difference between EUI-64 and IPv6

I understand that Extended Unique Identifier (EUI-64) allows a host to automatically assign itself a 64-bit interface identifier IID for an IPv6 address. My question is: What is the purpose of using ...
2
votes
2answers
973 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 ...
1
vote
3answers
1k views

Summarize subnet from 4 ip addresses

I am trying to figure out how to summarize the subnet for ip route. I am following this information here... http://www.pearsonitcertification.com/articles/article.aspx?p=2169746&seqNum=7 It ...
1
vote
3answers
6k views

Overlaps with VLANS

This's problem SW_R2(config)#int vlan 2 SW_R2(config-if)#ip addr 172.16.0.129 255.255.255.240 SW_R2(config-if)#int vlan 3 SW_R2(config-if)#ip addr 172.16.0.145 255.255.255.224 % 172.16.0.128 overlaps ...
3
votes
1answer
10k views

Can same port configured for different IP address or different protocol

I read following line from port WIKI So, does it mean that same port, let's say 7001 can be bind to a different IP address or different protocol? As per my knowledge, it cannot be and would result ...
1
vote
4answers
184 views

IP protocol functionality

In TCP/IP protocol the IP layer gives the minimum functionlity .It does not provide any flow control or doesn't have provision for acknowledgement. Why is this done ?why is the functionality of IP ...
2
votes
2answers
377 views

How subnetting works on network design?

Maybe this question is very easy for some people. I know very basic of networking and I am trying to learn more. I have followed tutorials on Microsoft and I read this: Using a subnet mask of 255....
1
vote
1answer
83 views

Unsecured devices and IPv6

I'm currently starting to read up on IPv6, and as soon as I heared that every device can/will have a public accessible adreess i got a little freaked out. There are a lot of horror stories about ...
4
votes
1answer
505 views

Network Diagram for IPv6 LAN

From what I understand about IPv6 networks, since NAT was a hack to deal with a lack of IP addresses in IPv4, NAT is a possibility, but not a requirement in an IPv6 LAN. So taking this into account,...
0
votes
1answer
55 views

Routers and RIP violation of isolation?

I'm studying networking from the book 'A top down approach' from Kurose and Ross. In the book it is stated that routers are generally considered Layer 3 devices (i.e. implementing the stack up to ...
2
votes
2answers
477 views

IPv6 can't ping host when static route configured with exit interface

I have the following topology (using IPv6) interfaces: I have the following static routes configured on it: R1#sh ipv6 route static IPv6 Routing Table - default - 9 entries Codes: C - Connected, L -...
14
votes
2answers
3k views

Why are there 3 ranges of private IPv4 addresses?

Why are there three separate ranges of private IPv4 addresses of different sizes? Why not just reserve the largest (10.0.0.0 - 10.255.255.255) range and let people create /16 or /24 (or whatever) ...
2
votes
2answers
236 views

Connection between 2 end devices with different subnet masks (Packet Tracer)

I was just wondering why Packet Tracer allows 2 end devices to ping each other even though they're specced with 2 different subnet masks? am i missing something here? i.e. PC1: 192.168.1.10/24 PC2: ...
6
votes
4answers
3k views

Why do I get “% Warning: use /31 mask on non point-to-point interface cautiously” when I use a /31 subnet mask?

Why do I get % Warning: use /31 mask on non point-to-point interface cautiously when I use a /31 subnet mask over Ethernet, and why am I not able to ping from R1 to R2 when both the interfaces have ...
3
votes
2answers
208 views

Bad mask for Cisco simulator GNS3

I am using the GNS3 simulator, and I need to connect two Cisco C7200 routers. When I enter the ip address 126.0.0.4 255.255.255.252 command, I get Bad mask /30 for address 126.0.0.4.
0
votes
1answer
52 views

How does a router forward datagrams from the internet to an interface of a private network?

As I have seen in How does a router know to which PC in a network to send a response from a server? if I haven't misunderstood it, if an interface in a private network sends a Datagram to the outside ...
2
votes
1answer
323 views

Inter-PVLAN communication on Arista 7050S

We have an Arista 7050S configured with a few PVLANs. All hosts on these PVLAN share the same /24 network (major flaw?). They can communicate between themselves within each PVLAN and with the gateway (...
7
votes
1answer
263 views

Is the first address of the subnet a valid configurable address in case of IPv4 and IPv6 point to point networks?

Am I correct, that first address of the subnet is a valid addresses to configure in hosts/routers in case of IPv4 and IPv6 point to point networks? For example, in case of 192.0.2.0/31 one of the ...
1
vote
1answer
311 views

IPv4 to IPv6 one-to-one mapping for a whole Class A range

Are there any IPv6 technologies that support translating one-to-one mapping from IPv4 to IPv6 for the whole Class A range, like 10.0.0.0/8 network to a particular IPv6/40 range? Preferably for A10 AX ...
4
votes
6answers
1k 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 ...
2
votes
1answer
248 views

What it means to configure two global ipv6 address on a single interface?

I have seen some network configuration files where a single interface is assigned with two different but similar ipv6 addresses, what is the significance of it, ex : interface te 0/1/0/10 ipv6 ...
58
votes
7answers
16k views

Why are IPv4 addresses running out?

I understand that we are running out (or ran out already?) of IPv4 addresses, but I don't really understand why that is. Right now, every home has its own IPv4 address (dynamically assigned, but still,...
1
vote
1answer
325 views

What happen underneath when I manually change my IP address?

When I move into a new dormitory, the network manager in the network center tells me my IP address, DNS address, gateway address, and stuff. I was told to just plug in my cable, enter these addresses, ...
5
votes
1answer
4k 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?
2
votes
3answers
878 views

Same IP addresses with different CIDR notations, is it possible?

Can we have exactly same IP addresses with different CIDR notations? Example: 194.24.0.20/20 194.24.0.20/21 194.24.0.20/16 194.24.0.20/24 194.24.0.20/29 194.24.0.20/15 And so on... How will it ...
1
vote
1answer
129 views

Basic understanding of network operation

Assume two stations, A and B, are connected by two intermediate routers. A----R1-----R2----B Now, when A sends a packet to B, then the OSI model will come into the picture. Like, A's TCP layer will ...
10
votes
4answers
2k views

Using IP subnet at multiple datacenters

We control IPv4 and IPv6 subnets. Now we'd like to use a part of a /24 IPv4 subnet at one datacenter and another part at another datacenter. I know that announcing the subnet on the internet at ...
1
vote
1answer
30 views

Is it possible to implement virtual network based on MAC in IP instead of MAC in UDP?

We know that flannel use MAC in UDP to create a overlay network. My question is: UDP header only provides an extra port number fields, let's suppose that one physical machine only run one flanneld ...
1
vote
1answer
46 views

I am trying to set up aDHCP server in a VLAN for practical of networking with Linux

I am a Linux user requesting advice about setting up a DHCP with a VLAN based on offices on one floor for the practical purpose. Is this good enough for implementing a VLAN structure with a DHCP ...
4
votes
3answers
67 views

Native IPv6 load balancing

We have two software gateways (on Linux) for IPv6 that take fullviews from ISPs and announce our AS. And several nodes connected to Internet via the gateways. Something like at picture: And we ...
2
votes
2answers
86 views

Public IP addresses

Are all Public addresses connected to each other? Can I ping my friend's public IP address on another side of the world? or public addresses are divided into groups( something like private and public ?...
2
votes
1answer
58 views

My OSPF Multi Area Topology is not reliable

I made an ospf multi area topology, but it's inconsistent. At times, host from the A area could ping to hosts in other areas however, sometimes otherwise (failed to arrive). Whenever I tried to do a ...
-1
votes
1answer
117 views

Dividing IPv4 Network into 7 Subnets? [duplicate]

I've been trying to figure out how to divide a network IPv4 IP Address into 7 subnets, where each subnet requires a different number of hosts. For example I have the question: "You are an intern at ...
3
votes
1answer
45 views

Quagga router advertisement messages are wrong after an address change

I have a problem with Quagga OSPFv3 implementation. I have a Mininet topology with a host connected to a router. I assigned an IPv6 address to the router interface. And I enabled IPv6 ...
3
votes
1answer
61 views

How can hosting providers give you a dedicated IP adresses?

Some hosting providers give you an option to get a dedicated IP address with your hosting package. For example: Digital Ocean gives every droplet that you create its own dedicated IPv4 address. I can ...