Questions tagged [layer3]
For questions about the OSI layer-3 (network layer).
262
questions
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13 views
Till what complexity does a Layer 3 perform better than a L2 switch and a dedicated router? [closed]
Layer 3 switch is a switch that can perform L3 functions, such as inter-VLAN routing. A L3 switch can offload those tasks from the routers (1). For a small network, obviously, what the switch can ...
2
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1answer
54 views
What is the impact of “no switchport” with “no ip address”?
I've a monitoring tool named Spectrum from CA Click. It automatically forms links between devices by check their configuration, and etc. Recently a change was made on my switch by a regional and the ...
0
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2answers
61 views
Link failure detection between 2 routers
When 2 routers are linked directly together with eBGP between them, how is a link failure detected ? With the BGP timers ? Or faster with some sort of L1 tool?
For instance, assume we have the ...
6
votes
2answers
1k views
How do I know the switch is layer 2 or layer 3?
Is it possible to find the switch is Layer3 or Layer2 in (Switch)CLI? Is there any command to check whether the switch Layer(Layer 3 or 2) in CLI?
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2answers
43 views
How does an L3 Supported Switch differentiate L2/L3 Packets?
I had a managed or layer 3 supported switch (it can process both layer 2 and layer 3 packets). Now a packet from a connected host comes to it, sending traffic. How does the switch decide to process it ...
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0answers
18 views
Switch vs. Router and sequence of OSI Model [duplicate]
As I understand it:
A switch (layer 2) seems to define a LAN and a router (layer 3) enables communication between distant LANs.
A device on a LAN will give it's MAC address to the switch upon ...
1
vote
2answers
55 views
Some extra clarification regarding VLANs and SVI
Good afternoon guys,
I've got a question regarding VLANs and SVIs.
First of all, I know some concepts about VLANs, and I've been in the IT field for a while.
But this one is a bit confusing for me.
...
1
vote
3answers
100 views
Why is in all arp table snmp oids an interface index before the ip number?
When I want to get arp information about a single ip number or subnet, I have to snmpwalk the whole arp table, as some oid architects had the "great" idea to always insert an interface index ...
1
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1answer
42 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?
0
votes
1answer
989 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 ...
0
votes
2answers
71 views
Connecting 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 link to a L3 switch.
Both the L2 and L3 switches have x4 10GbE ...
1
vote
3answers
208 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 ...
0
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2answers
51 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?
1
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2answers
30 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 ...
0
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0answers
26 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 ...
1
vote
2answers
95 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
14 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 ...
0
votes
1answer
63 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 ...
2
votes
1answer
74 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 ...
1
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2answers
173 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 ...
0
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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 ...
0
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1answer
100 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. ...
0
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3answers
484 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 ...
2
votes
2answers
195 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
votes
1answer
145 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
votes
1answer
61 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
vote
1answer
86 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 ...
4
votes
2answers
765 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 ...
1
vote
2answers
121 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 ...
0
votes
2answers
222 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 ...
0
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2answers
60 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
105 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.
3
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1answer
132 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 <----...
0
votes
2answers
172 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 ...
0
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1answer
212 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
votes
2answers
487 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 ...
0
votes
1answer
114 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, ...
3
votes
2answers
204 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 ...
4
votes
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 ...
0
votes
1answer
857 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 ...
0
votes
4answers
226 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 ...
0
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0answers
20 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 ...
0
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3answers
106 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 ...
0
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2answers
82 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
votes
3answers
658 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?
2
votes
2answers
622 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)
...
0
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2answers
417 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 ...
2
votes
6answers
564 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 ...
0
votes
1answer
131 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
votes
2answers
281 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 ...
