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Questions tagged [link-layer]

20 questions
14
votes
1 answer

What are the data link protocols for cellular networks?

What are the link layer protocols for cellular networks? There are several platforms for high speed cellular networks. From GSM, to GPRS, W-CDMA, HSPA, LTE, etc. I (mostly) know about the physical details of radio transmission from what I studied at…
Panda Pajama
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7 answers

Should Cat6 cables be used for servers ('important hosts') rather than Cat5-E?

Wouldn't you want your crucial hosts being served with the most signal-reliable/improved method of connectivity? Gig Switch<->Cat5E<->Server? or Gig Switch<->Cat6<->Server? My understanding about Cat6 is that it delivers improved signaling between…
l0c0b0x
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4
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2 answers

ARP responds with single MAC address on Linux server with multiple interfaces on the same network

Linux server has 2 active network interfaces: IF:eth1 IP:192.168.1.1/24 MAC:11:11:11:11:11:11 (1GbE) IF:eth2 IP:192.168.1.2/24 MAC:22:22:22:22:22:22 (10GbE) The idea is that the 10GbE interface (eth2) is the primary interface for…
sardean
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4
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3 answers

Network link layer equivalent of `ping` to probe a device which fell from the intranet?

Here's my situation. It's hypothetical, but happens often enough to be a problem. We have a generic layer 2 ethernet network switch. All of the devices connected to this switch use IP addresses in a 10.1.1.0/24 private network. We attached a new…
Stefan Lasiewski
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How to setup an encrypted L2-Tunnel using MikroTik Routers?

What I would like to achieve I want to securely spread an existing internal subnet over multiple buildings. That means that I have two locations with virtual machines that need to be within the same subnet. The idea is that the virtual machines…
SDwarfs
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How to get the topology of a layer-2 switch network with the switches' forwarding tables?

Suppose I have a list of layer-2 switches that do not support LLDP (Link Layer Discovery Protocol) but support SNMP. I have the management IP addresses of these switches, but I don't know how they are connected to each other. I am able to get the…
F32
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1 answer

Different MAC addresses in packet and ARP table

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 and will be filled via an valid ARP response. Now…
fitcfitcfatc
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Need confirmation on layer 2 security question

I need confirmation on a question regarding layer 2 security. I've been doing research and I just need to know that I understand it correctly. Basically, if you have a LAN with a few machines connected to a switch, and those machines are…
Mediocre Gopher
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3 answers

Can data link layer do IP fragmentation in some special cases?

I'm reading book TCP/IP Illustrated, Vol.1 and there it says that IP fragmentation is done by network layer. This is how I understood the concept so far: Network layer (L3) creates "IP datagram" (IP header + data) and sends that byte array to data…
David
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1 answer

Blindly bridging wireless client with MAC NAT

This is the usual "I want to bridge wifi with ethernet" question, but I need something specific here. My Linux box has a wlan0 interface which is in station mode, with MAC aa:aa:aa:aa:aa:aa, and a VLAN interface (vlan0) with MAC bb:bb:bb:bb:bb:bb.…
Alba Mendez
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1 answer

Layer 2 bridged networking issue with QEmu

I am having a problem with a layer 2 bridged network configuration using Linux, QEmu, and VMware ESX. The configuration works fine on a small isolated network, but once introduced into our large corporate network, problems arise in the network…
kgraney
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4 answers

Cisco Switch: trigger mac-address table update

If I run show mac-address-table dynamic I get a bunch of mac addresses on that table. But due to the aging parameter, I don't see the mac addresses of all possible devices on the network that come through that switch. Is there a way to force an…
Megaslav
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5 answers

About the link layer of TCP/IP

I know there're ethernet,token ring,FDDI ,etc protocat the link layer, but how to know the exact protocol used to perform a specific task,like browsing a web page?
kernel
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How many bits for sequence number using Go-Back-N protocol

I'm a regular over at Stack Overflow (Software developer) that is trying to get through a networking course. I got a homework problem I'd like to have a sanity check on. Here is what I got. Q: A 3000-km-long T1 trunk is used to transmit 64-byte…
Mike
1
vote
1 answer

Forwarded Packets are received by namespace's veth0 but not received by application

I use libtins (It uses Pcap) to capture link layer packets and forward to a network namespace where the actual application runs on. Client(Browser) -> Server -> Pcap -> Pcap Send -> br0 (Bridge) -> Namespace -> Application Now, I see that the…
sqlbie
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