Questions tagged [layer3]

For questions about the OSI layer-3 (network layer).

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1answer
27 views

When traffic is intiàted from pc is ANDing process or ARP process start working first

When traffic is initiated from desktop which process starts first; the ARP process or ANDing process?
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1answer
48 views

intervlan routing with PfSense

I Need some guidance on getting my lab networking configured. Any support is appreciated. My Lab consists of: 2 cisco switches: 2960s(access layer 2) and 3750X(ip routing/layer 3) Xenserver with ...
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2answers
37 views

Connecting switches together

I've gotten confused about connecting the switches together. I have L2 switches which will be daisy chained together (yes I know, daisy chaining isn't great, but anyway..) The L2 switches will then ...
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3answers
85 views

Minimum MTU size on Ethernet and minimum Ethernet frame size

I am a bit confused about the understanding of the relationship between minimum MTU of MTU and minimum Ethernet frame size. We know that the maximum MTU of Ethernet is 1500 Bytes which makes the ...
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2answers
40 views

Layer 2 managed switch and layer 3 switch

If you have layer 2 managed switches which have VLAN's on them, do you still need a layer 3 switch/router?
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2answers
26 views

What is the need for the NEXT HOP coloumn in the routing table when we already mention the OUTGOING INTERFACE in another coloumn?

If the OUTGOING INTERFACE is already mentioned in the routing table, it is natural that the next hop will necessarily be the router attached to the outgoing interface. Then why is there a separate ...
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0answers
22 views

network cutover for remote site from L2 to L3 over IPSec tunnel

I have been trying to cutover one of our remote sites (A) to the new ISP we have purchased. The existing setup is utilizing L2 through another remote site (B) and coming back to the main campus. The ...
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2answers
74 views

Are all packets addressed with the MAC address of the router as they leave the machine?

In the Comptia Network+ All in One, it is said that most home routers have a switch built into them. It is also said that the first thing the router does is strip off any layer two information present ...
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0answers
13 views

Basic Subletting 10.239.142.216/11 [duplicate]

First time poster (kindly don't eat me alive) i was using https://subnetipv4.com/ to acid test my subletting skill i got 9/10 correct this is the chosen one that broke my streak as you can see i ...
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1answer
54 views

Why does the Layer 3 switch drop the ping packet?

I am trying to ping from PC2 (not PC1, there's typo in the picture) to the router's int g0/0, but the packet is dropped at the L3 switch which is along the path. I have tried setting a default static ...
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1answer
70 views

what were the classless routing protocols used with VLSM when it was first introduced?

Since VSLM is supported only by classless routing protocols, if VSLM was introduced in 1987(RFC 1009) and all classless protocol(RIPv2 developed in 1993 , OSPF standardized in 1989 RFC 1131 ) cited ...
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2answers
69 views

Vlan vs. Subnet Broadcast Domain

It is my understanding that Vlans separate broadcast domains, but I often see people say, "subnets define a broadcast domain" as well. Is it correct to say, "Vlans define a L2 broadcast domain, and ...
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0answers
14 views

Understanding OSI communication model from Electronics Perspective [duplicate]

I have gone through the OSI communication model and the associated levels. But I do not understand on how is this implemented in the Hardware level. Or let me put it like this. Suppose we have a USB ...
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2answers
54 views

Question on ARP

Given the above diagram, is it correct to say that the ARP cache table in PC A contains the IP-MAC addresses for PC B and the router, while the ARP cache table in PC B contains the IP-MAC addresses ...
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1answer
39 views

How does a 802.11 (wifi) frame identify the payload's layer 3 protocol?

My understanding is that the 802.11 frame header is an equivalent of ether header. In the ether header, there is an EtherType field that identifies the payload protocol, such as IPv4/IPv6/ARP etc. ...
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3answers
158 views

Clarification on when routers encapsulate and decapsulate packets

I'm an application developer working on getting a working knowledge of network engineering, so basically a newbie. I've been trying to figure out exactly when routers decapsulate frames into packets ...
1
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1answer
75 views

How do computers send switches packets, if switches don't have IP or MAC addresses?

I am new to networking, so please excuse me if I am saying stupid stuff. From my understanding, PCs are sending packets to switches, which then decide which physical port to forward that packet to. ...
2
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1answer
79 views

Why Classful addressing is not in use if we can subnet them?

So, Let's think that organization needs 5000 IP addresses. Giving 20 C Class IP addresses will cause of adding 20 entries for ISP router. That's problem. We could give Class B IP address, but that ...
2
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1answer
48 views

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 ...
1
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1answer
31 views

Question about MTUs vs maximum frame sizes - what is their difference?

I am currently studying networking at university and I have a question about MTUs and maximum frame sizes. What is the difference between the MTU and the maximum frame size? This Wikipedia article ...
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2answers
743 views

Confusion about data fragmentation/MTUs - why was it introduced in the first place?

I am currently studying networking as a part of my bachelors and I am a bit confused about why fragmentation/MTUs are necessary. In my lecture slides, it only says "Fragmenting if necessary" under the ...
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2answers
97 views

Question about the destination IP inside an IPv4 packet

I'm reading about link and network layers for the first time and I'm trying to put the pieces together to understand how they work together. My question may not have to do with the link layer but I'm ...
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1answer
102 views

Unable to ping between router and routed port on L3 switch. Why?

I've got an old Cisco 2811 connected to an old Cisco 4948 L3 Switch. I'm trying to teach myself a little more about L3 Switch implementation. All I'm trying to do at this point is get the router and ...
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2answers
53 views

Can Northbound interfaces (REST API) in a Software Defined Network (SDN) be used to manipulate QoS parameters?

I am working on a project involving Quality of Service (QoS) manipulation in Software Defined Networks (SDNs). I know that the following parameters affect the QoS in an SDN: Time information (inter-...
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1answer
48 views

2 machines can have the same link-local address, in the correct context. What context?

I don't get in what context multiple interfaces/machines can have the same link-local address. Thanks in advance.
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1answer
90 views

Query on PTP Transparent Clock

I had a query in PTP Transparent Clock(TC), Please consider the below picture for my question. I will try to express my question with the help of a real world example Say, two places Place_A <----...
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2answers
107 views

Unicast to Multicast possible?

could I check if it is possible to convert TCP traffic to UDP multicast and if there are any appliances / switches that can do so? E.g. Workstations A, B and C establishes a TCP connection with ...
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1answer
205 views

Why is default gateway in routers configuration usually set as an IP address?

I mean why not just: a MAC address? It should eliminate the need in ARP requests asking for gateway address. Also it should eliminate the need in changing IP addresses in settings when gateway IP is ...
4
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2answers
465 views

Is a datagram from an upper network layer converted 1:1 to one of the lower layer?

I know datagrams from upper layers are converted to those of lower layers by adding metadata, but I cannot seem to find this information anywhere. Which one of the below is correct? A single TCP ...
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1answer
56 views

Unicast Adjacency Routes Nexus (AM) Cisco Nexus

I have an odd situation. There is static route on my Nexus 7700 that routes anything for specific subnet /24 to a F5 LTM Load Balancer, external VRRP interface 10.x.153.15. As you can see below, ...
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2answers
145 views

What is the advantage of Supervised Machine Learning over Deep Packet Inspection in Network Traffic Classification?

As per the definition of Deep Packet Inspection (DPI), it uses signatures for packet filtering. Supervised Machine Learning can help put a label on a packet which does not get identified by Deep ...
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3answers
2k views

How does Deep Packet Inspection work with encrypted packets?

I've been reading up on Deep Packet Inspection for Software Defined Networks. However, I know that some applications use encryption to evade Deep Packet Inspection. Is there any alternative (such as ...
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1answer
442 views

What is the theoretical difference between the link layer and the network layer?

I have run into this problem again and again and have never found a sufficient answer to this question. I want to understand the fundamental, theoretical difference between a layer 2 network and a ...
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4answers
141 views

ACL on routers to block TCP/UDP ports

How routers understand the layer 4 port numbers to be blocked in ACL? When an ACL to block TCP/UDP traffic with certain port numbers is applied on a router/L3 interface , how will router understand ...
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0answers
19 views

how OSI and TCP/IP layers work? [duplicate]

I am really confused by how the layers these model work. I'm not asking about what are their functions. I read that transport layer provides end-to-end of all packet delivery, and networking also ...
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3answers
99 views

Regarding Cisco's hierarchical network design

why routed ports usually implemented between the distribution layer and the core layer ? why not just extend the layer 2 domain to the core layer ? is the other design model more practical than this ...
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2answers
73 views

switch died after slow to rapid failure now DHCP will not function across network even with new switch

ok so i'm running out of ideas here. we have/had 3 managed switches in our server rack and one in a closet; one hp procurve 3500yl 48 port with poe for 2 APs and 2 catalyst 2960s in the bottom of the ...
4
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3answers
526 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?
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2answers
433 views

Why do transport layer do data chunking. If there is fragmentation in Network Layer

I just curiously wanted to know about the question regarding L4, L3 Data Chunks, IP Fragmentation : Data chunking happened at Layer 4(Transport, TCP), and Fragmentation at Layer 3(Network, ipv4) ...
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2answers
284 views

Different MAC addresses [closed]

What happens if a host on the network receives an IP packet with a MAC source address that differs from the MAC address in the local ARP table for that source IP. The ARP table entry for that IP was ...
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5answers
330 views

Is a “LAN” a layer 2 or a layer 3 concept, in TCP/IP?

I think my question is purely theoretical and a matter of definitions; it derives from the fact that a L2-switch with VLAN capabilities is able to "create" different virtual LANs, and thus I am led to ...
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1answer
87 views

Layer 2 and Layer 3 traffic with one cable

Hers the topology. L2 switch L3 switch Router There are 2 VLANs. One VLAN ends on the L3 switch 1 VLAN on the router. Here is the question. Can i connect the L3 switch and the router with just 1 ...
3
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2answers
265 views

What are neighboring ports?

I know this is as basic as it gets but I can't find a direct answer to this question. Are they ports on two different switches (or routers) that are connected by a cable? Are they the ports ...
2
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1answer
24 views

Understandable/Implementable explanation of CSMA p - persistent

I have been trying to understand how the CSMA P-persistent method works, but haven't been able to understand how it's implemented. I have referred to a few textbooks and other sources, but all of them ...
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1answer
462 views

Arp Cache Timeout [closed]

I'm trying to poll the arp table from a backbone switch but i want to understand which records are up. I just want to know if there is a specific time for the switch to keep a record on the arp table ...
3
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2answers
214 views

Is static routing used in large networks?

I'm a beginner in networking stuff and just wondered if Static Routing has any use in large networks ? How about small ones ? In which cases we prefer to use static over dynamic routing ? I searched ...
3
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1answer
1k views

MAC Table vs ARP

I understand that for a switch to learn a MAC address, if host A wanted to send data to Host B the switch learns host A MAC and places it in the MAC table. If it doesn't know where the MAC (for Host B)...
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1answer
1k views

Successful Intervlan Routing on a Layer 3 Switch, Unsuccessful IP Routing

Hello and thank you in advance for your help! I'm using Packet Tracer for testing purposes and I' m trying to implement a simple intervlan routing in a Layer 3 Switch (3560-24PS) and an IP Routing. ...
3
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3answers
2k views

Is it possible to perform a Layer 2 (MAC address) traceroute?

I understand the difference between layer2 & layer3 and MAC & IP. I understand address resolution protocol, etc. But is there any way to do a traceroute that will show Layer 2 information? For ...
4
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3answers
1k views

Does a router send frames or packets?

Perhaps it's a novice question, but does a router send/receive frames? When I read about this subject, it seems that routers decapsulate the frame on arrival, and encapsulate the packet in a frame in ...

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