Questions tagged [layer3]
For questions about the OSI layer-3 (network layer).
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Catalyst InterVLAN Routing w/ Failover ASAs
I currently have interVLAN routing configured on my Catalyst 3750. My gateway of last resort is my ASA firewall. The switch reaches the firewall through a layer 3 port. The port is configured as ...
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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 ...
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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 ...
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INTER-VLAN Routing with different Internet Access for each vlan
I have a situation that needs some clarification.
I have three sites (1,2,3). The core switch do Inter-vlan routing. Site 1 and 2 must access the internet via ISP1, while site 3 will access internet ...
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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 ...
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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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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 ...
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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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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 ...
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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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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 ...
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InterVLAN Routing Plan
My network currently has 7 VLANs (2 user, 1 voice, 1 server, 2 wireless, and 1 for our networked A/V equipment). All of our switches are layer 3 Cisco Catalysts. However, we currently have a router-on-...
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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 ...
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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 ...
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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.
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RVIs and routing out of firewall
I have managed to configure a number of EX3300 switches (using virtual chassis) with vlans and the appropriate layer-3 configurations for RVIs.
I can get the traffic to flow internally on the ...
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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, ...
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Pinging a different vlan without routing
I have a layer 3 switch with two vlans 10 and 20. This is the only configuration i made on the switch:
Switch(config)#vlan 10
Switch(config-vlan)#name IT
Switch(config-vlan)#vlan 20
Switch(config-...
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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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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 ...
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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 ...
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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 ...
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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?
...
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Juniper EX how to clear route forwarding table?
After layer 3 routing a large IPv6 assignment on an EX Juniper switch, the route forwarding table filled up and some entries corrupted or became otherwise invalid. We want to clear the whole table. ...
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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) ...
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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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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 ...
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In IPv4 does the identification field in a TCP packet change for fragmented packets?
If a TCP packet is fragmented then would the identification field of the header stay the same for all of the fragmented packets, or would it increment by 1 so that the receiver would know what packet ...
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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 ...
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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 ...
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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 ...
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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 ...
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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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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.
...
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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 ...
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Need of routers and IP addresses
I dont know if my research is enough or not but I could not find answers on the net.
My question is why not use bridges instead of routers. We know bridges can connect two different networks. Using ...
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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 ...
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Does a switch understand packets? If yes, what is the frame terminology for?
I was a little confused between packet and frame. The confusion was based on, if a switch is a layer 2 device, how does it reads a packet from a layer 3 device, and where is the 'frame' thing which is ...
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spanning tree at layer 3
we want to prevent loops in the network be it LAN or WAN. However for layer 2 LAN networks STP is used to prevent looping switches.
However at layer 3 TTL field is used.
why not use STP for layer 3 ...
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ARP spoofing in different VLAN
I want to know if I'm protected for ARP spoofing.
In my network, all PCs, printers, phones and servers are in distinct VLANs. I got a layer 3 switch for servers, which handles routing between these ...
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Understanding VLAN tagging
Let's say we have 4 machines connected to a layer 2, managed switch which is connected to a layer 3 switch. Say that 1.2.3.0/24 is routed to the layer 3 switch. Our goal is to have 1.2.3.0-63 usable ...
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Cisco cross-vlan routing
I have the following config snippets on a layer 3 switch:
ip routing
!
interface GigabitEthernet1/0/22
switchport access vlan 51
switchport mode access
!
interface GigabitEthernet1/0/23
switchport ...
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RIB vs FIB differences?
Can someone explain the differences between a RIB and FIB a little further? I didn't see any similar questions on the site so I thought this would be a good addition. The RIB routes and the FIB ...
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Why does Neighbor Discovery Protocol have to monitor upper-layer protocols?
While reading the RFC of NDP I wondered, why it is necessary to monitor upper layer traffic in order to know if a neighbor is reachable, e.g. a TCP ACK.
I do get the IPv6 packet anyway, so I know it's ...
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Cisco 800 series guide
Recently, my company bought a Cisco 881. Although I am able to get it up and working by copying some configuration on the Internet, I still do not understand how does the layer 2 (LAN) and layer 3 (...
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Inter VLAN with layer 2 and 3 switch
Is there a way to interconnect VLANs using this diagram?
MLS0 has this configuration:
interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
And SW0:
interface ...
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What are the advantages of a firewall over a Layer-3 switch?
From my understanding, a Layer 3 switch can handle cross-communication between separate LANs and VLANs, as well as fine-tuned ACL control between VLANs.
Despite this, I know a Layer 3 switch should ...
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mLACP or vPC on L3 interfaces
I just want to know if it's possible to implement mLACP (with VSS) or vPC on L3 interfaces. I just can't find any answer to this on cisco doc.
Thanks,
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Can a router send ARP requests to hosts?
I play with libpcap in C recently to create an arp sniffer program that captures arp requests on the air. I came up with a strange effect. I captured arp requests from my router. I don't know if this ...
user33076
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Need Advice From Experienced Techs Please - For Charity Organization in Africa [closed]
1st: I would like to thank you for your time.
2nd: I was asked by a charity organization to help building a system and network for the charity center where they help the most needed groups in the ...
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