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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.

2
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2answers
150 views

Broadcasts in IPv6

I'm aware of the fact that broadcast has been removed from IPv6 and just has multicast instead. However, recently I read "This process (ARP) is now achieved via a multicast address called the ...
4
votes
1answer
14k views

Assign an IP to a MAC Address to DHCP POOL

The idea is that I want to have a static IP for the MAC computer always assign me the IP . please help , as would the commands ? I have a cisco 3650 switch core where I configured the DHCP and VLAN ...
2
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1answer
231 views

IPv6 - RA prefixes and flags

I'm trying to understand how SLAAC works, but having troubles understanding how the information inside the Router Advertisement is used by a client. Let's say neither the Manager nor the Other ...
2
votes
1answer
1k views

Are there public servers with a 192.168.X.X IP address?

I was wondering about the IPv4 problem and thought about one of the solutions where endpoints do not have their own public ip address, but rather an address only used within the VPN and a mapping by ...
2
votes
2answers
1k views

Connect to switches with the same IP

We used to have one site with one Cisco switch to which a RANCID server was connected to take configuration backup. A new site was opened, and we have another switch on this new site. The sites have ...
4
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5answers
10k views

How many IP addresses can a device or an interface possess?

Can one IP address be assigned to more then one device or interface? In which situations may this happen? Can one device or interface posses more than one IP address?
3
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1answer
546 views

What is the point of a subnet mask on a local network?

I have a question regarding subnet masks and my understanding (or misunderstanding of them). So when a subnet mask is used, a bitwise AND is performed using the subnet mask and the IP address(es). ...
3
votes
3answers
5k 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 ...
1
vote
2answers
311 views

How are packets routed based on IP and how are those routes acquired?

Good day all, this is my first question here, be gentle in judgement Background: At university, we are covering Network Routing Protocols. Having possibly found 2 issues with current routing ...
1
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1answer
381 views

UDP and fragmentation calculation

Assume we have a ethernet link with an MTU of 1300 bytes, while an application want to send 5200 bytes of data. How many fragments do we transmitted ? i would say 5, to send 5200 bytes over a link ...
7
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2answers
126 views

VLAN clarification

I've inherited a network with approximately 200 computers and no VLANs configured. We are currently adding a system that uses multicasting to communicate with each other and will be adding VoIP in 2 ...
3
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2answers
8k views

Mac address and IP address in physical addressing in Data-Link layer

Framing is done in Data-Link layer. We give physical addresses there. Destination address, source address and MAC. If two PCs in different networks, we try to sent data from one another, we specify ...
2
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4answers
4k views

Does every subnet have broadcast and network addresses?

Given /26 subnets for a /24 network: Subnet 1 0-63 Subnet 2 64-127 Subnet 3 128-191 Subnet 4 192-255 Does every subnet have its own network ID and broadcast address? Meaning: Subnet 1 0-63 (...
1
vote
2answers
668 views

Is my dynamic IP address provided by my ISP shared?

The IP address provided by my ISP changes. I want to know if it is shared by someone else in this world.
2
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2answers
2k views

What is the difference between MAC and İP broadcast addresses?

As far as I know, they are both used to send a packet to all hosts that are connected to a local arena network. Why would anyone need two addresses to send a broadcast package?
1
vote
1answer
138 views

Clustered Juniper devices using public DoD IP addresses for communication?

Ok, so I have to admit I am not an expert in how Juniper networked devices work, so this entire issue might be why I am having issues understanding something I am seeing on a pair of clustered SRX210H'...
2
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2answers
468 views

IP Fragmentation

When Device A sends an IP datagram toward Device B, the IP Layer of Device A computes if it must or not fragment the IP datagram to fit the link MTU. Sent to the next hop, the process will be repeated....
1
vote
1answer
317 views

Help setting up multiple IP ranges on same subnet

So long story short. We setup our network YEARS ago, when we were a small company of only 10 people. Now, we are pushing 100 employees, and my network has outgrown itself. Originally, I setup the IP ...
1
vote
2answers
124 views

What does it mean if an Ethernet Card has two RJ45 ports?

Ethernet is below IP in the OSI model. But how is an IP address actually assigned to an Ethernet port? I know, that Ethernet has nothing to do with IP, but under Windows I can assign an IP address ...
3
votes
3answers
253 views

Is it ok to leave the trailing 0's off in IPv4 CIDR notation?

In IPv6, we can collapse 0's when talking about addresses. In IPv4, can I write 192.168.1.0/24 as 192.168.1/24? Can I write 10.0.0.0/8 as 10/8? I'm working on some software that takes CIDR's as ...
2
votes
2answers
1k views

Subnet masks vs. IP address ranges

Let's say I have a network with 17 devices. The minimum mask I could use to accommodate these 17 devices is 255.255.255.224 (i.e. /27), which itself can contain 30 useful addresses (excluding the ...
5
votes
3answers
1k views

VLANs and Subnets Smaller than /24?

I would like to get some advice on this, because I see it being mentioned repeatedly, but why are VLAN subnets recommended to be /24? What are the downsides to assigning VLAN's a subnet that are ...
1
vote
1answer
3k views

Do routers discard packets if they don't know where to forward them?

If a router receives a packet whose IP destination address is not in its routing table, I believe it will send it to its default port. Suppose that we erase that entry from the table. Now, I think ...
10
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3answers
11k views

Find MAC address of a remote computer using IP

Is there a way to find out a computer's MAC address if we know its IP address, assuming this computer is outside our LAN? I know we can easily get the physical address of a computer in our LAN using ...
5
votes
2answers
4k views

What would happen to Ping if two PCs have same IP address with same Subnet Mask on same network?

If there are two PCs with same IP address on a LAN, what would happen if I ping that IP address from another PC on the same network and why?
9
votes
1answer
1k views

What happens when a subnet reaches capacity?

Other than not being able to claim any more IP addresses in a subnet, what other bad things happen when a subnet reaches 100% utilization, if anything?
-1
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1answer
34 views

Find Major network vslm

Im a bit lost with this question. In order to get proceed with the vslm i need to find the Major network of this subnet 121.118.40.0 /19. For me the major network is 121.118.32.0/19, but when I run ...
1
vote
1answer
59 views

Finding the network address for given host IP?

Answer provides the procedure to find the network address when a packet with destination IP(198.51.100.223/21) is reached at a router. But a network packet has the destination IP 198.51.100.223 in ...
3
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2answers
4k views

Where in the TCP/IP stack does packet division and reassembly occur?

My understanding is that 1/ the Transport Layer in the TCP/IP stack creates packets for data that is being sent out, and 2/ the packets reassembly process occurs at the receiving end's Internet ...
0
votes
1answer
62 views

How are websites accessed without port numbers?

I am confused on how requests to websites are received. If I type in 172.217.5.110 to my browser, google.com sends me its home page. I didn't have to specify the port number. How does that work? I ...
-1
votes
1answer
42 views

Why CIDR block is assigned to subnet? [duplicate]

If VPC is assigned CIDR block 172.31.0.0/16, then I can create sub-nets within VPC, following this procedure: 172 . 31 . 0 . 0 255 . ...
3
votes
1answer
1k views

Multiple ip address on a interface advertisement

The network topology is router A and router B are directly connected with IP addresses configured on their physical interfaces int gig 0/0/1 and gig0/0/2. The third interface gig0/0/3 is configured as ...
5
votes
1answer
3k views

Smallest IPv6 block advertised?

We've received a /48 allocation from ARIN, and want to advertise smaller blocks from different sites in our organization. I tried advertising a /56 from each site, but ISP is telling me they won't ...
1
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1answer
85 views

L3 Etherchannel cost calculation

Q1: I have read that in layer 2, if any of the links of a portchannel goes down,the cost of the portchannel is recalculated. Does that apply to L3 portchannel also? If so, assume I am running OSPF in ...
2
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2answers
171 views

How does anycast ensure reliable delivery of IP packets for the same IP address on different locations?

With anycast, it would be possible to have the same IP address at multiple locations in the world, without the need of a proxy or VPN that forwards the packets to its final destination. If you would ...
2
votes
1answer
71 views

Why specify the source tunnel address?

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/868-cisco-router-gre-ipsec.html Let me use the same example as in my previous question. R1(config)# interface Tunnel0 R1(config-if)#...
1
vote
1answer
505 views

OSPF Area Multiple Subnets

Is it possible to have multiple subnets in one OSPF area? Everything I can find so far points to the answer being 'No', however I need to know for sure if it's possible or not. Our current setup is a ...
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 ...
0
votes
1answer
450 views

Private Public and Special IP addressing

Is the IP address 224.0.0.0 routable over the internet?
5
votes
3answers
231 views

Learning switches and routers

I'm taking a computer networking course and i struggle to get to flow of things when it comes to learning switches and routers. Lets say we have a AS with LANs that connected with switches, and there ...
7
votes
5answers
8k views

Why is the protocol field part of an IP header?

Note this is not a duplicate of Why is the IP layer aware of higher layers in the network stack? The need for a protocol identifier (eg. the IP header's Protocol field) in packet-based communication ...
1
vote
1answer
139 views

Configuring a switch to connect to public IP address to create a private network

Our institution has a public IP address and now we want to create a private network using a switch which can connect to the Internet through this IP address. What class network should we use, and what ...
9
votes
2answers
2k views

Is there anything stopping me from using Class A addresses on my own network?

I've been reading about IPv4, networking, subnetting and the different classes of addresses. I understand that IP addresses beginning with numbers from 1 to 126 are considered "Class A" addresses. ...
1
vote
1answer
154 views

How does a packet travel across multiple routers/subnets?

After reading various resources and examining the example below, the step-by-step process for a packet to travel the route below is still not 100% clear to me. I'm hoping to get clarification. Image ...
0
votes
1answer
272 views

IP Addressing-Why All zero(0) and all one(1) in subnet id bits are reserved?

I'm studying about class less inter domain routing. I've come to know that all zeros(0) in host id bits refers to subnet address and all ones(1) in host id bits refers to broad cast address. So, ...
12
votes
2answers
4k views

Is the MTU of Ethernet still 1500 Bytes?

So basically do the modern routers in the internet still use 1500 as the MTU of Ethernet? or the 1500 Byte was for the old days? What I'm asking here is what is the MTU of Ethernet in modern Networks?...
0
votes
2answers
656 views

Can a subnet mask contain zeros between ones? [duplicate]

In theory, can a subnet mask have zeros between ones (e.g. 255.255.0.248) or it need to be strictly 1's followed by 0's? As stated in RFC 950, there is only an "example" to interpret an IP as <...
2
votes
1answer
4k views

Why is the minimum MTU of a IPv4 packet 68 bytes?

According to RFC791: Every internet module must be able to forward a datagram of 68 octets without further fragmentation. This is because an internet header may be up to 60 octets, and the minimum ...
0
votes
1answer
658 views

TCP/IP Header compression

I'm reading RFC 1144 and I'm trying to figure out how the TCP/IP header compression works. As I understand it, the sender only sends a couple of fields that are likely to be changed. If the packet ...
0
votes
1answer
2k views

May every IPv6 address be written as an IPv4-mapped IPv6-address?

In RFC 5952 - section 5 it is stated that for some IPv6 addresses it is recommended to give the mixed notation, if it has a certain prefix. However, it is unclear which prefixes are used for this, ...