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Questions tagged [autonegotiation]

For questions about Autonegotiation in a network perspective, where Autonegotiation is an Ethernet procedure by which two connected devices choose common transmission parameters, such as speed, duplex mode, and flow control. For instance, you are troubleshooting an issue where a host doesn't negotiate the correct link speed.

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How exactly does an Ethernet collision happen in the cable, since nodes use different circuits for Tx and Rx?

I am trying to understand how a collision occurs in Ethernet, especially when a duplex mismatch exists or when on a legacy Ethernet network two nodes transmit simultaneously. Everyone explains the ...
3
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2answers
326 views

On RJ-45/UTP with 2 pairs, (Tx, Rx) which pair will be used in case of half-duplex?

On RJ-45/UTP with 2 pairs, (Tx, Rx) which pair will be used in case of half-duplex? How is decided and conveyed between the two ends, when auto-neg is not enabled?
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1answer
501 views

Verifying 802.3 auto negotiation

This is my setup: The Problem The end point, ethernet device B, is powered by the power injector but receives no data. Everything is connected using CAT5 cable. Ethernet device A signifies a GB/s ...
1
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1answer
498 views

Capture auto-negotiation ability flags

I'm performing a set of tests on an embedded device, one of which is "To verify that the control system and instrument supports auto-negotiation". I need to verify that "Expected auto-negotiation is ...
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3answers
163 views

The recommended settings for giga ethernet connected to Ethernet port

What is the recommended duplex and speed configuration for giga ethernet port connected to legacy ethernet (10 mbps) port and there is no available duplex command available on the ethernet side? If ...
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1answer
65 views

Is it possible.. Partial Duplex: 100mb one way & 1000mb the other

I have a potential application where the vast majority of the traffic will be in one direction, and, concurrently, I have a potential alternate use for a pair of wires in the cable that would ...
2
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2answers
226 views

Who sends Autonegotiation FLPs first in a link at 1000BaseT

In 1000BaseT the same pairs of wires (all four pair) are used both for transmission and reception. In this gigabit mode how is it decided which of the link partners will send FLPs first. Further what ...
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2answers
255 views

How links come up, when an autoneg disabled FE port is connected to Autoneg enabled 10/100/1G port

I was just learning about auto-negotiation and got some doubts. As per the standard 802.3 clause 28, 10BASE-T ports transmits LIT or NLP pulses to make the link UP. https://en.wikipedia.org/wiki/...
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3answers
702 views

Do I need Auto-Negotiation in 1000BASE-X Ethernet if I have a point-to-point link always at 1 Gbps?

I have a point to point connection by fiber with 1000BASE-X Ethernet. The rate is always at 1 Gbps, and I believe full-duplex would not be a problem. Since the link is point to point, it seems that ...
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3answers
263 views

How to connect an old network card (10 Mbps) to a new network (1000Mbps)

I have a system that has an old network card, supporting 10 Mbps Half duplex. Is there a way to "wrap" the system with a router or switch that will allow me to connect it to a 1000 Mbps full duplex ...
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0answers
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Why auto negotiation cannot be disabled on Fiber Port

I tried to disable auto-negotiation in my Juniper ACX-2200 , but it says edit#set interfaces ge-0/1/0 gigaether-options no-auto-negotiation raki@# commit [edit interfaces ge-0/1/0] 'gigether-...
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1answer
60 views

sleeping computer on gigabit ethernet kills multicast performance

Problem: any sleeping computer on a gigabit network causes all multicast traffic to drop to 10Mbps. Solution: provide customers with managed gigabit switches and train them to configure the switches ...
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4answers
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What's the point of auto-sensing 10/100 Mbit/s Ethernet?

According to the notes I'm reading: 10/100 Mbit/s Ethernet refers to the standard that can autosense which speed it needs to run between speeds of 10 Mbit/s or 100 Mbit/s. Why would autosensing be ...
2
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1answer
561 views

1000BASE-T with “no autonegotiation”

802.3 requires 1000BASE-T interface to do autonegotiation. But many network gear can disable autoneg and force 1000M-FDX operation for 1000BASE-T interface (such as "no autonegotiation / duplex full / ...
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2answers
3k views

Forced full duplex and autonegotiation

Let's say I have two connected switches. I specifically configure (force) one of them to use full duplex and the other one I configure to use autonegotiation. Why does this config fail and the autoneg....
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2answers
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How does auto-negotiate determine link speeds?

I have two Linux hosts connected via category 6 wire. How do the LAN cards negotiate a link speed? Essentially, I am trying to solidify if I am actually hammering a 1GbE NIC with traffic from a 10Gbe ...
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2answers
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Enabling flow control on my ethernet NIC

When running "ethtool eth0", I get a line in the output that states -> Supported pause frame use: No Does this mean my Ethernet card does not support flow control at all? I try to enable the flow ...
3
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3answers
463 views

Simulate/Deactivate link status recognition for 100BASE-TX [closed]

My question is related to creating an unidirectional network cable. I used these tutorials: Receive-only UTP cables and Network Taps ONE-WAY CABLE FOR IDS DEPLOYMENT In principle it works by ...
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1answer
74 views

Why are there so many different Network File Systems & File Transfer Protocols? [closed]

I've been spending a lot of time trying to learn different Network File Systems & File Transfer Protocols etc. in order to integrate three different devices with three different Operating Systems: ...
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2answers
194 views

Is collisions between fastlink pulses possible during auto-negotiation?

Auto-negotiation uses fastlink pulses to help a device determine the speed, duplex mode and other details of the link partner. However it is not clear from the ieee802.3 autoneg section what happens ...
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1answer
1k views

HP 1810-24G and Mikrotik CloudCore1036 - 1Gb link negotiation problem between [closed]

MY QUESTIONS ARE: What could be the cause of this nondeterministic HP switch behaviour ?! Why sometimes devices make 100Mb link and sometimes 1Gb ?! At above picture You can see part of my network ...
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3answers
1k views

Autonegotiation disabled, different speed, hub

I am beginner in networking and I have two questions, because I can't understand it well. I know how auto-negotiation works, but what happens if two connected devices have different speeds and auto-...
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1answer
4k views

No auto-negotiation for X520 with 10G direct attach cable?

I'm looking to use auto-negotiation and send Ethernet pause frames across a connection between an Intel X520 NIC and a Stratix IV FPGA using a 10G direct attach copper SFP. Ethtool is telling me that ...
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2answers
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Building a 3 port network tap (100mbps half-duplex)

I've tried building a network tap with only three ports: the two communicating parties and a tap side. I knew this would force the communicating sides to use at most half-duplex 100mbps, but detection ...
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2answers
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Ethernet autonegotiation differences between (10M | 100M | 1G) Ethernet

I am studying for CCNA and on Wendell Odom's book is said that(regarding autonegotiation): When autonegotiation fails on one node, to choose (half/full-duplex) we must use the rule: If you have a 10/...