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

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3answers
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Why do clients request a MAC via ARP, if the router knows the local LAN's MAC addresses already?

If I have an infrastructure type network, why does a local PC send out an ARP request for a MAC? Doesn't the router know the MAC addresses already, since it is using at least Layer 2? Does it do ...
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1answer
31 views

Connecting Layer 2 switchport to layer 3 port

I have a config that I am trying to bring up, and in my mind it should work, but perhaps I am missing something. The idea is that one end of the link is a layer 3 interface on a router. The other end ...
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0answers
22 views

What is the network address of this subnet? [duplicate]

I need help solving this question as i am not very good in networking lingo. Insert the Layer 2 and Layer 3 addresses used the following transfer from computer A to computer B. How many IP Addresses ...
0
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1answer
23 views

Separate network for test systems

I often read that you should put customer machines into a separate (testing) network like a DMZ. Is a layer 3 device (switch/router + firewall) a good option for this? Since some ports need to be ...
3
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5answers
375 views

Is there a Layer 2 address advertising protocol?

I needed help in understanding if LLDP/CDP is the Layer 2 equivalent to RIP or say any Layer 3 route advertising protocol. If not,is there a protocol that advertises the MAC Address Tables among ...
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1answer
36 views

Routing and Bridging on a Layer 2 or Layer 3 device

The thing that intrigues me is, say I have a router and I configure it’s interface as a Layer 2 and have 2 Vlans on the same router. So if I want to transfer the data from one Vlan(say VLAN-10) to ...
0
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1answer
35 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
1answer
136 views

At which layer does router operate?

I have studied from various sources that router is a layer 3 device. It does routing based on Network layer (layer 3) header, but I have a doubt. Network address translation (NAT) is a feature of ...
2
votes
1answer
41 views

Weird networking behavior with a gateway between a switch and CMC module, on Dell VRTX equipment. Am I doing something wrong?

Diagram: Here's the simplest way I know how to explain how the internal networking of this Dell VRTX works. So, you have your 4 blades and your network switch module that have integrated remote ...
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3answers
716 views

What are the reasons for seeing an incomplete ARP?

As was mentioned in this post: The reason for seeing an incomplete ARP is that "An ARP request was sent for that address, but the host with that address is not up and running on the LAN, so there is ...
1
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1answer
92 views

Bridging networks without NAT: how it's done?

I have quite limited networking experience, so probably i'm asking about very simple things. I'm reading about linux bridge interfaces, and documentation states that there is no NAT by default and ...
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2answers
56 views

1 Layer 3 Switch, 2 Vlans, 2 Subnets, and an Unmanaged Switch

Is it possible to for a device with the ip address 192.168.0.1 and Vlan 100 to communicate with an other device with the ip address 192.168.1.1 and Vlan 200 with the following architectures Senario 1:...
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3answers
162 views

When is 'Timestamp' and 'Timestamp Reply' are used in ICMP protocol?

I started the packet capture in my laptop through Wireshark application. Now through cmd, I pinged some server (say, www.google.com). And i stopped packet capture and analysed the packets being ...
2
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2answers
106 views

Routing steps on a serial port

"Because the exit interface is not an Ethernet network, R2 does not have to resolve the next-hop IPv4 address with a destination MAC address." - this is routing from serial port , can anyone explain ...
3
votes
3answers
114 views

Layer 3 tunnel with Dynamic IP address

I want to ask whether it is possible to configure Layer 3 Tunnel with the two end points/interfaces have dynamic IP address? If the interface IP change, the tunnel will have to be re-negotiated, is ...
4
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5answers
579 views

Why can't two hosts (in two different logical networks) connected to each other through cross-over cable communicate?

Let us say, i have two computers (hosts) A and B. Where A has been assigned an IP address of 192.168.1.10/24 and host B has been assigned an IP address of 192.168.2.11/24. And both of them has been ...
1
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1answer
227 views

SD-WAN vs MPLS VPN

Citing wikipedia on MPLS VPN There are three types of MPLS VPNs deployed in networks today: 1. Point-to-point (Pseudowire) 2. Layer 2 (VPLS) 3. Layer 3 (VPRN) I am confused about the difference ...
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0answers
60 views

type of architecture leaf spine

Please I would like to know, what is the difference between the two types of leaf spine architecture (layer 2 and layer 3) and, is it possible to have a topology with both types? So the difference ...
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2answers
99 views

CGN and its advantages

I have been reading about CGN. Though similar to NAT it is used by service providers to route traffic without the need for the a public IP address. But when the packet leaves the ISP to the public ...
0
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1answer
76 views

Two Layer 3 Switches to one router

So I have a cisco 2811 router and 2 3560 switches Currently the router is connected to Core1 only, what i would like to do is use the other port on the router (fa0/1) to connect to Core 2. How do I ...
4
votes
3answers
270 views

How does a router a layer 3 device translate port address in PAT, as it is a layer 3 device?

While I was reading about PAT i.e Port Address Translation.The router was configured to translate all the private IP addresses to one single public IP.Since router is a layer-3 device, it can do that ...
3
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2answers
1k views

How to trunk VLANs over Layer 3 EtherChannel?

I am trying to setup a network that includes an EtherChannel link between two Cisco Layer 3 switches (Catalyst 3750). I am using a collapsed core hierarchical network. The picture above is my ...
0
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1answer
75 views

How to extend ports with L3 switch or other device? [closed]

I am a software engineer and no one in my team is familiar with network setup. My team recently bought 20 PCs for test our software but we only have 2 ports left in the room. And I have suddenly come ...
0
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1answer
561 views

Router vs VLAN in networking?

Why do we need Routers at all when we have VLAN ? Vlan breaks the broadcast domain. Vlan along with the use of SVI can be used for routing. So why do we need routers for in networking ?
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2answers
80 views

Is it possible to have a single port serve a layer 2 and 3 link simultaneously?

We are moving to a new L2 fiber network and i'm having trouble figuring out how to connect the DR. We are using a spoke and hub topology, with HQ as the hub. The branch locations all have unique ...
11
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2answers
5k views

VXLAN vs VLAN over layer 3

I read that one of the benefits of VXLAN over VLAN is that it can spawn across WAN and multiple layer 3 networks by creating overlay layer 2 networks. However AFAIN VLAN can also do the same using ...
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2answers
159 views

Does a router divide a LAN into two seperate LANs, or a single LAN with two subnets?

The figure below is part of a networking homework question. The question asks about the source/destination IP and MAC addresses of frames sent throughout the system. My question doesn't touch on that ...
0
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1answer
54 views

Default Action in SDN Controller

In legacy IPv4 networks there exists a default route concept for routers where a router does not need to know exact destination of IP packet. Is there a default action concept for SDN switches? Let ...
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1answer
46 views

L3 routing between switches with some VLAN's trunked

During a migration various L2 equipment will be replaced with all Cisco L3 switches and over time traffic migrated to routed subnets instead of trunked. There are two straightforward approaches that ...
0
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0answers
26 views

Palo Alto FW- If MultiVsysMode Disabled, What is the significance of L3 Intf Not Being Assigned to VSYS1 or a Zone?

If multivsys mode is not enabled, is there any significance to a layer 3 interface not being assigned to vsys1? Also, does an interface have to be assigned to a zone to be utilized in a palo alto ...
0
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1answer
54 views

Do packets take the same amount of time when they are within the MTU?

Without considering application processing or deep packet inspection, do packets that do not fragment all travel through the network at the same speed? For example, if there is a network with an MTU ...
1
vote
1answer
202 views

VLAN on Layer 3 Cisco C3560

I am looking to get a layer 3 Cisco switch and I know how to setup vlans, I will have the internet connection coming in from the pfsense router on port 1 and then vlan 10 on port 10 and vlan 20 on ...
2
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1answer
1k views

What's the difference between port number and protocol number?

Can someone explain it clearly. I know that port numbers are used by applications to differentiate which services you have requested, and routing protocols use protocol numbers in TCP header.
2
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4answers
297 views

Network service that is both connected and connectionless

I'm reading through Kuross "Computer Networking, a Top Down Approach". In the chapter about the network layer, they mention "In all major computer network architectures to date (Internet, ATM, ...
2
votes
1answer
99 views

Why does a layer 3 hop use vrrp secondary on nexus 6001

I have a nexus N5K-C5672UP as core layer 3 for our VLAN's. VLAN 601 on core 2 is secondary vrrp: core 02: core02# show vrrp Interface VR IpVersion Pri Time Pre State VR IP addr ---------------...
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1answer
106 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 ...
0
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1answer
325 views

Cannot access Internet from VLANs on an HP layer 2 and layer 3 switch

I have got an HP switch, layer 2 and layer 3 capable. I created some VLANs. I have an ADSL router on VLAN 1 with the IP address 192.168.1.2. From VLAN 1, I can access Internet, but from the other ...
1
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1answer
85 views

VSS for layer 3 only 6500

I have 2 6500 at the core, that have only L3 links to the DC and the campus. I'd like to set VSS but I'm wondering if it's possible in such scenario. It uses OSPF for the routing. I'll have the ...
0
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1answer
564 views

What is the proper switch configuration for the switch that is connected directly to ISP source?

The Question: What is the proper configuration for the L3 switch to be allowed to assign public IPs for the firewalls? I guess All I need is that the switch L3 act as a layer 2 switch...Right? ...
2
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1answer
47 views

Host behavior with mask +1 and -1

Let's suppose I have a configuration: host: 192.168.1.145/25 gateway: 192.168.1.129 network: 192.168.1.128/25 broadcast: 192.168.1.255 What happens if I add +1 bit and remove -1 bit to the mask? 1) ...
0
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1answer
291 views

How do we find the host name name by using mac address,VLAN or IP address on Layer3 switch [closed]

have quick question How do we find the host name name by using mac address,VLAN or IP address on Layer3 switch . i pull up the vlan and mac address using my IP by i couldn't figure it out the host ...
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2answers
1k views

How to make two Cisco switches talk to each other

I have a layer 3 switch with multiple VLANs. I created a trunk port that connects to a layer 2 switch. I can now successfully access the layer 3 switch VLANs from an access port on the layer 2 ...
5
votes
3answers
2k views

Layer 3 Switch Routing vs Router on a Stick

CORE: Dell N4032 (6.3.0.18) Access: Dell N2048 (6.3.1.13) We are in the process of setting up a serviced office that will serve multiple businesses. Each "customer" will naturally be on their own ...
2
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1answer
2k views

Designing a redundant switching infrastructure

Ultimately I've been tasked with the installation of a serviced office with upwards of 1000 staff, potentially being spread across 50+ VLANs. The hardware bought was out of my hands, but it's fairly ...
1
vote
1answer
480 views

HSRP on switch interfaces

As part of my internship/thesis, I am looking to implement HSRP in a network. The network has 2 separate locations that are connected with a fibre cable (layer 3 to layer 3). Each layer 3 (Cisco ...
4
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3answers
407 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 ...
2
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1answer
416 views

VLAN vs Subnet in switch

For VLAN communication we need a layer 3 device. For internetwork communication, we also need a layer 3 device. Then why did concept of VLAN emerge?
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2answers
55 views

Lab: I have a ISR with layer 2 ports that i need to connect to a 6500 layer 3 routed port

on my network vlan1 is to be non routed management traffic between switches etc. vlan2 is general network vlan3 is wifi vlan4 is a point to point between routed interfaces vlan5 for servers. ...
5
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1answer
556 views

Inter-VLAN Routing with VTP Server and Clients in Packet Tracer

I am new to the networking world and am attempting my first few projects in Packet Tracer. The first few were easy but I've gotten to a road block. My goal is to have three separate VLANs with at ...
0
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1answer
32 views

Am I correct to start thinking in terms of “ports” as “networks” or “devices”?

For the longest time, when I would configure a network device I would login to the GUI, and assign it an IP address. As I am getting into Cisco and their ISO model, I am seeing more and more of ...