Questions tagged [layer3]
For questions about the OSI layer-3 (network layer).
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How to configure static routing between two layer 3 switches?
I have two Cisco layer 3 switches. In switch 1, I created two vlans, 10.10.1.0/24 and 10.10.2.0/24. The connection is shown in the figure.
PC 1 and PC 2 have static IP address (10.10.1.5 and 10.10.2....
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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 ...
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Lowest Possible Failover Latency
Let’s say I have two networking devices (either L2 switches, L3 switches, or routers), and the two devices have two ethernet connections between them: port 1 to port 1, and port 2 to port 2. If one of ...
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Encapsulation and decapsulation basics for OSI layer
I have read that encapsulation takes place down the layers while decapsulation takes place up the layers. In essence, the encapsulation starts at Application layer all the way upto Physical layer.
...
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Regarding Bridge domain and L2 vpn
I am trying to understand the usage of bridge group command.Please refer the following config(on switch ASR9k):
l2vpn
!
bridge group TEST1
bridge-domain BD1
interface Bundle-Ether1.500
...
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How does a network cryptor work?
I want to know at which layer is a network cryptor used. What are the features of routers used for encrypted packets?
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Understanding Broadcast address
Please validate my understanding for the following points with regard to broadcast address:
1.Broadcast address is relative to a network, so every n/w will have it's own broadcast adress(I can obtain ...
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Configuring 2 layer 3 switch with VLAN
I am trying to create 2 vlans- 10 and 20 where 10 is for user and 20 is for DMZ. vlan 30 created is to link between vlans 10 and 20.
Right now I'm only able to ping user from vlan to their switch and ...
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Packet transfer from one host to another
I was reading about how a packet is send from one host to another. I am confused about entries that will be made in layer-3 switch routing table. Does it contain the entries for layer two switches or ...
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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 ...
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Is there a way to detect whether router is ASBR in OSPF?
Am using open source OSPF software from ospf.org and running ospf daemon in host PC.
If router has interfaces in multiple area, then its an Area Border Router.
Is there a way to detect the router is ...
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HSRP Issue Both sides are active ( Layer 3 4300 X serires)
Why does HSRP shows both sides are active HSRP? Could you please give me details answer?
First router:
**Vlan111 - Group 6**
State is Active
5 state changes, last state change 2w4d
Virtual ...
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1
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How can I apply an ACL to interface on a Layer 3 switch?
I try to accept ACL on L3 switch inteface. I've created standard ACL via:
SW-L3(config)#access-list 1 permit host 1.1.1.2
SW-L3(config)#access-list 1 permit host 1.1.1.3
Then i tried to execute this,...
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If a bypass switch is an L1 device, what happens when bypass mode is enabled?
Okay, a bypass switch works at L1, and when an inline appliance like an IPS or firewall is connected to the bypass switch, the bypass switch simply grabs all traffic coming in an either side and ...
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Can I Use BGP as an IGP - Multisite w Redundant Layer 3 MPLS WANs
The requirements are
Hundreds of sites.
Each has a router and firewall and a switch stack.
Layer 3 MPLS WAN with BGP to provider VRF.
BGP as an IGP?
iBGP
Would you distribute a public ASN across all ...
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How to connect different networks based on vlans using layer 3 switches and router?
This is a simplified version of my network diagram. How do I make both network speak to each other?
I'm confused because earlier I used routers and switches, and I connected them using OSPF or EIGRP....
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Use of BGP by Enterprise / Medium Businesses with Layer 3 MPLS WAN
Scenario:
Assume no Internet connection for the sake of this question, the scenario is basic - 5 offices connected by an MPLS WAN. The customer is handed a Fast Ethernet (100Mbps) circuit at each ...
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Best method for rate limiting ingress & egress traffic hosts in colocation
What is the best method for the limiting speed of internet access for hosts in our colocation. We have a full rack which will be connected to the internet at 200/200 Mbps. We have our colo equipment ...
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HP 5400Rzl2 strange ACL behaviour
Hello to all of you experts.
I'm sorry if this is a dumb question (I usually don't ask those, but I'm human), but I haven't a clue of what's wrong in this environment.
I wish to permit all my VLANs ...
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Switching vs Routing
I have seen quite a few discussions regarding MPLS stating things like:
MPLS combines the performance and capabilities of Layer 2 (data link layer) switching with the proven scalability of Layer 3 (...
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Can't ping through L3 switch
I've built a scenario in Packet Tracer that I am looking at implementing but having issues with pinging from a PC through a L3 switch. From the switch, I can ping every IP address in the environment ...
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How do protocol stacks determine the destination mac of reply packets?
Suppose a network stack receives an incoming message:
Ethernet sees that EtherType is IPv4 so the payload is forwarded to the IPv4 handler
IPv4 sees that the IP protocol number is ICMP so the message ...
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Difference between routing, forwarding, and switching
I feel like the three terms are often used as synonyms but actually all mean something different. I did look at Wikipedia sites but I'm still unsure about the definitions of the three.
From my ...
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Cisco VRFs and L2 inter-switch communication
I am having trouble wrapping my brain around a VRF concept and why two switches are communicating with each other on a particular VLAN when I don't think they should.
switch1 & switch2 are ...
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In the TCP/IP model, how does the application layer inform the Internet layer of the destination IP address?
New to networking.
How does the application layer inform the Internet layer of the destination IP address? Let's say I make a Http request to www.google.com, which the application layer resolves to 8....
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Ping over Trunk Port Juniper
Let's say I have one vlan on one switch and another vlan on another switch (2 EX2200 Juniper). I have a trunk between the two switches on which both vlans are members. What do I need to do to allow ...
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Calculation accounting for Layer 2 overhead when viewing traffic statistics
Recently, I was on a Juniper device, trying to figure out why I was getting a lower bit rate even though I knew I was sending a lot more.
Then it hit me that Juniper devices show the Layer 3 ...
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How do you ping between VLANs?
I have created VLANs on the layer 3 switch and I would like to ping between them, how do i do so?
I would like to allow VLAN 2 to ping VLAN 3, how? What command should I use?
new#sh ip interf ...
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Multicast forwarding through VLANs for KVM Over Ip [closed]
I'm currently designing a terminal-server architecture, using KVM-Over-IP technology (I'm using Gefen devices) where I have four VLANs:
One VLAN for the displays at 192.168.240.0/24
Three VLANs for ...
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Problem with Routing in VLAN
I am trying to set up several VLAN's on a Cisco 3560 switch. These new segments should be able to communicate with VLAN 1 and even access the Internet.
Basic IP information:
Gateway: 10.1.1.2
VLAN1: ...
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On a Layer 3 switch, what part does the CPU play in forwarding packets?
I am a Systems Administrator at a small firm. We are latency sensitive. When forwarding packets, what protocols use the CPU and which use the ASICs?
We have mostly Arista 7124's (for the most latency ...
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Load balancing between multiple layer 3 switches
I have two trunked L3 switches forming a network backbone. One is an old HP2848 and the other is a new Juniper EX3300. Currently only the EX3300 connects to our WAN Router and is trunked via 4 LACP ...
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Routing between two networks
I had a question here.
Basically, we have two different networks. Each network has one Cisco 2960 layer 2 switch for each network in the same location. These are two individual networks. There is a ...
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How can fat tree ensure bandwidth?
I'm reading about fat tree and data center topologies, but I have doubts.
To lower cost, "normal" tree is used sharing bandwidth to many hosts. 1:1 is not common, so we see something between 2.5:1 ...
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Exiting to a Router from Layer 3 Switch with SVI enabled routing
I am trying to simulate a network, I am having problem directing traffic to exit the L3 Switch and to go to router for routing to outside network. (I don't want to use routing capability of switch, ...
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How to use a layer 3 switch for QOS between gateway and hosts?
In the following scenario, is it possible to prioritize VOIP/RTP from x.x.x.51 through the gateway with a Cisco switch, and how? I need to prevent x.x.x.50 from saturating the WAN connection.
...
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General network comprehension
I wrote a program that does packet communication with a server and something has been in the back of my head for sometimes :
When I analyze packets with WS I can see in the header first off two MAC ...
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Assign IP address to a FastEthernet port on CPT switch
I've configured a vlan 3 with ip address and then assigned FE port to vlan 3 , i read that this will assign the ip address to the FE interface.
I know this is really simple configuration .But really ...
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theory: connecting two computers with ethernet cable [closed]
I am fairly new to networking but have done manual Linux command line wireless connections and home router configuration.
The internet is full of how-to guides on transferring files between two ...
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How does a TCP segment go through the Internet Layer in TCP/IP?
I'm currently learning the reference models. It's said that TCP/IP supports only connectionless communication in the Internet Layer but both connectionless and connection-oriented in the Transport ...
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Optimizing access control lists on a Cisco SG500X-48 Small Business switch
I am trying to optimize the access control list rules on a Cisco SG500X-48 Small Business switch (on Layer 3). The general aim is to regulate the traffic between two VLANs (e.g., 10 and 30) in such a ...
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What practices/ mechanisms/ protocols can be used to secure communication on physically exposed Ethernet links?
Given that Ethernet cables are everywhere and use for all kinds of links and it is assumed they are physically guarded, hence typical installations do not leverage any "secure" mechanisms.
Let's say ...
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What is the difference between layer-2 and layer-3 broadcasts? Please explain with an example
What is the difference between broadcast addresses ff.ff.ff.ff.ff.ff (Layer 2) and 255.255.255.255 (Layer 3)?
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Inter-VLAN Routing
I am trying to configure inter-VLAN routing, but I can't route using MLS. I attached the image. Please check and give the answers.
In switch0 I created VLANs 2 and 4; in switch1 only VLAN 3; in ...
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InterVLAN routing with one layer 3 switch
I'm looking to set up InterVLAN routing with one layer 3 switch within Packet Tracer (multiswitch), and then have 12 machines connect to these switch. The 12 machines are split between 4 VLAN's as ...
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Accessing devices on different subnets using a switch
I have two devices which come up with default IP addresses:
Device 1 - 192.168.168.168 mask 255.255.255.0
Device 2 - 192.168.1.254 mask 255.255.255.0
I can commonly deduce that both the devices ...
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VLAN Tags and QoS
I have a bunch of phones that are tagged as VLANID 20 with priority 7. I have the router setup with VLAN Tagging as well to mark VLANID 20.
My question in terms of switches. Do the switches need to ...
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Why is the ICMP protocol considered to run at layer 3 on the Wikipedia page?
Why is the ICMP protocol considered to run at layer 3 on the Wikipedia page (same layer as IP) when the ICMP protocol data is a payload of the IP packet?
This is the article on Wikipedia that states ...
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Cisco MLS - single port carry L2 and L3 packets
While learning networking concepts I learn a network hardware port can be switch port to carry MAC headers or Routed port to carry L3 info.
However, Cisco MLS concepts as I understand a switch port ...
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Campus Area Network questions
Looking for design principles in regards to a Campus Area Network? We are a medium sized company with < 250 employees spread across 4 offices. We will soon be combining 2 offices into 1 larger ...
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