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Questions tagged [layer3]

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

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4
votes
3answers
564 views

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 ...
4
votes
2answers
8k views

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)?
6
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5answers
1k views

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 ...
2
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1answer
2k views

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 ...
1
vote
1answer
2k views

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 ...
6
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4answers
2k views

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 ...
2
votes
1answer
95 views

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 ...
4
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3answers
202 views

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 ...
18
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3answers
7k views

What do TCP/UDP add to “raw ip”?

I know that both TCP and UDP are built on top of IP, and I know the differences between TCP & UDP, but I'm confused about what exactly "raw ip" is. Would it be fair to say that TCP & UDP both ...
1
vote
2answers
113 views

Cisco Nexus 6004 Layer 3 capabilities

My organization currently has a pair of Nexus 7010's (Sup-1's) in one of our smaller data centers as our core switch (we still currently implement a Core-Dist-Access model). Long story short, this ...
2
votes
1answer
2k views

Does the spanning tree protocol come as standard in L3 switches? [closed]

Online there is a lot of content mentioning the spanning tree being a l2 switch feature so I guess it comes as standard/ is a given that it available for all modern l3 switches... (Could the answer be ...
3
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3answers
2k views

Cabling standard for Layer-3 switch

I want to know the appropriate cable type between: Layer-2 and Layer-3 switch Layer-3 switch and router Is it cross-over or straight through?
6
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4answers
3k views

Advantage of layer 3 switch over Router

What is the advantage of Layer 3 switch over the Router ??
1
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1answer
318 views

Why PPP cares about network layer?

Why PPP have protocol field? Isn't whole purpose of partitioning communication system to have simple isolated subsystems?
2
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3answers
4k views

What is the difference between ff-ff-ff-ff-ff-ff (layer 2 broadcast) 255.255.255.255 (layer 3 limited broadcast)?

Please explain the flow of traffic in each case.
2
votes
1answer
148 views

Where exactly is the limited broadcast address used?

I read that limited broadcast address will be dropped by the router. So, it's not used in the layer-3 (Network layer), where IP addresses are meant to be used. So, where exactly is it used?
1
vote
1answer
579 views

Is “Layer-3 switch” a combination of router and switch?

I noticed there are some switches called "Layer-3 Switch", which is able to do both switching and routing. I have seen some articles that says Layer-3 switch can replace routers. Is it going to ...
9
votes
3answers
1k views

What is a “Layer 3 Switch”?

What is a "Layer 3 Switch"? I essentially understand the OSI model, well maybe I don't and maybe that is why I don't understand. Its just that I don't see how/when/if a "managed switch" becomes a "...
2
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3answers
3k views

What is the relationship between the IP address and MAC address?

I own a MAC address and I want to know from it, the IP address.
4
votes
1answer
2k views

Help with VLANs, ACLs, DHCP on SG-300 Layer 3 switch

I have to do the following configuration on an cisco Sg-300 small business L3 switch as in the figure. Since i don’t have access to this switche for practice before doing this live in production i ...
2
votes
1answer
60 views

Inter Vlan Packet Transfer

I am trying to establish communication between 2 devices within different vlan. But I require a router for that. Can I send packets within different VLAN without having a router or a Layer 3 device.
2
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3answers
2k views

What is Routing Daemon?

Reading about IP Routing, I found a brief explanation: "routing daemon, which is normally a user process. The most common daemons used on Unix systems are the programs routed and gated." In an Unix ...
2
votes
2answers
482 views

IP Fragmentation

When Device A sends an IP datagram toward Device B, the IP Layer of Device A computes if it must or not fragment the IP datagram to fit the link MTU. Sent to the next hop, the process will be repeated....
3
votes
2answers
461 views

SonicWALL TZ215 : 2 LAN interfaces and 1 WAN

Here is network schema: 192.168.2.200 - Switch layer 2 ---| |--X0 LAN 192.168.2.254 |---Switch layer 3 ---| 10.50.40.40 --- Swtich layer 2 ---| ...
2
votes
1answer
143 views

How do I use my SP Ethernet connection between HQ and Branch for Layer 2 and Layer 3

I am looking to use my provider Ethernet Connection between our HQ and Branch to do Layer 2 and Layer 3. The Ip addresses I hope to use for the remote are those being advertised to the ISP using BGP. ...
6
votes
1answer
3k views

Assistance with routing between layer 3 switches with ospf

I have two Cisco 3560's in a branch office. One acts as an access switch configured with two vlans: interface Vlan10 ip address 192.168.0.254 255.255.255.0 interface Vlan20 ip address 172.16.0.254 ...
2
votes
1answer
268 views

Metro Ethernet no layer 3 connectivity

We're working with a metro ethernet provider to bring up a new multi-point connection between our sites. Currently we're just trying to get it working with two sites. As a simple test I've plugged in ...
4
votes
1answer
283 views

Optimizing Network Topology

Recently I wish to split the network by VLANs. Mainly for two reasons Exclude management interfaces from the commonly accessible lan Separate WiFi traffic (security and broadcasts) The current idea ...
3
votes
1answer
10k views

Can same port configured for different IP address or different protocol

I read following line from port WIKI So, does it mean that same port, let's say 7001 can be bind to a different IP address or different protocol? As per my knowledge, it cannot be and would result ...
1
vote
2answers
427 views

Netgear switch required default gateway for point-to-point link [closed]

So, my Netgear switch died, and after factory resetting it, I noticed that I was unable to connect to it. The Netgear was configured for 192.168.0.239/24, and I configured my windows PC to 192.168.0....
2
votes
2answers
296 views

Does the Cisco 3560-CX support Layer 3 Etherchannel?

Does the Cisco 3560-CX support Layer 3 Etherchannel? I can see from the specs that this switch supports Layer 2 Etherchannel and that it is a layer 3 compact switch. However, it doesn't have the full ...
2
votes
2answers
14k views

Inter VLAN routing working, but VLANs can't access Internet

i have a question/problem. i have a local router with default-gateway 192.168.3.254, now on my layer 3 switch 3560 i configure 3 vlans. vlan 10 - data /ip address 192.168.10.254 255.255.255.0 vlan ...
1
vote
2answers
379 views

Which network protocol is used for media streaming from online music or video sites? [closed]

I would like to know which network protocols are used for media streaming by online music and video sites ?
1
vote
1answer
453 views

the difference in dealing of Layer 3 Switch and Router with broadcast communication

How does L3 Switch deal with broadcast communication such as ARP,DHCP or Broadcast storm? Is it the same that router deal with such as blocking a broadcast communication or ip address "255.255.255.255"...
1
vote
3answers
6k views

Why should I use Router on a Stick If already doing interVlan routing using L3 Switch in same netwrok? [closed]

I have this network in which the top switch(one connected to router) is used for routing between all the vlans in the network. I have defined vlan interface in this switch, but I haven't configured ...
4
votes
4answers
44k views

Intervlan routing using two Layer 3 Switches in Packet Tracer

I am having trouble when I am using two Layer 3 switches and two PCs to create a simple network for Inter Vlan routing, First of all have a look at this network, The configuration for PC1 is, IP: ...
3
votes
3answers
6k views

D-Link L2 & L3 Network Setup

I'm currently setting up my new network using D-Link DGS-1510 series gigabit stackable smart managed switches. It is the first time i use this L2 & L3 switches and I'm trying to setup the ...
2
votes
2answers
2k views

Regarding MPLS L2 Vs L3

I'm studying about MPLS Network, i've doubt on that i.e., what is the difference between MPLS Layer-2 Vs Layer-3 Network ?
-1
votes
2answers
796 views

Restricting IP subnets to specific VLANs (Brocade ICX)

Say I have an uplink port (1/3/1) connected to our upstream, then various clients across 1/1/1 - 1/1/48. I want to create two or more VLANs where each VLAN can only use IPs from a specific subnet. e....
0
votes
1answer
976 views

Inter VLAN - switch layer 3

I tried to configure simple topology using switch layer 3, but it doesn't work and I don't have an idea what is wrong. When I ping from 192.168.1.2 a computer 192.168.2.3 , a ICMP packet stops at ...
4
votes
3answers
5k views

Layer 2 vs Layer 3 core - with HP IRF

The SMB organization I work for is migrating to HP/3COM Comware L3 switches and we will be implementing the standard Core>Distribution>Access design. Please refer to this diagram for clarification: ...
1
vote
2answers
2k views

HP 1910 disable layer 3 mode

Is there a way i can make HP 1910 works in layer 2 mode. I check the web interface but not seeing anything Also i enable the cli and went to system view but not seeing any thing related no ip routing ...
7
votes
4answers
496 views

Why is the IP layer aware of higher layers in the network stack?

In the IP packet header there is an 8-bit Protocol field (at offset 9) that holds the "next level protocol", with assigned numbers given in RFC 790. For example, TCP is 6. My question is, why is the ...
3
votes
1answer
2k views

Should my layer 3 switch rewrite this MAC address?

I have the following routing table: say I get packet with dest IP 10.5.89.34 and the next hop IP is that of a logical VLANIF94 interface. please explain what all steps will happen here like MAC ...
6
votes
3answers
3k views

Quagga OSPF DR/BDR Mismatch: Losing Routes

I am experiencing a problem with lost routes in an OSPF over DMVPN environment. I am running ubuntu server 14.04 with Quagga 0.99.22.4, and OpenNHRP 0.14.1. While technically the DMVPN network is an ...
2
votes
1answer
350 views

How can a telecommunications carrier convert his layer 3 transmission network to layer 2 at client site?

Ok, my company has three telco providers, each telco provides data links from the central site to different remote sites. Telco provider 'A' provides layer 2 "dedicated" fiber optic links from the ...
2
votes
4answers
1k views

Should I receive an ARP reply from a host that is logically on a different subnet but is connected to my host via a hub?

Host A: 128.238.66.100/16 Host B: 128.238.67.100/24 The hosts are connected to the same hub and nothing else is connected to that hub. The routing and ARP tables of both hosts are empty. Host A ...
2
votes
2answers
8k views

Routing the same subnet in two locations / gateways?

In my current topology, I have two locations linked by a trunk. Everything on one side of the trunk is Site A, everything on the other is Site B In the example above, for 10.0.200.4 to talk to 10.0....
5
votes
3answers
422 views

Why use 'switching' term for packet switching

On a packet switching network, a router is required to route packets to different networks. Why does packet switching uses the term 'switching' when a packet is a term for a layer 3 PDU and ...
-2
votes
1answer
97 views

L3 switch - All L3 processing offloaded to card?

On a Cisco 3560 switch, are all L3 processing offloaded to card instead of normal CPU?