Network Engineering Stack Exchange
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1500 questions
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5 answers

Should i run UDLD with spanning tree?

Can spanning tree and UDLD be run together, and if so, is this a good idea?
Aaron
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8 answers

How to connect 5 different networks together?

I have a network consisting of three servers in a data center, all of which are connected to each other via a switch. In addition to this I need this network to access 4 additional networks, most of which are provided via cross connects to other…
Kranar
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3 answers

Serialization and serialization times in 40G/10G and 100G/25G Ethernet

I've recently been involved in discussions about lowest-latency requirements for a Leaf/Spine (or CLOS) network to host an OpenStack platform. System architects are striving for the lowest possible RTT for their transactions (block storage and…
Marc 'netztier' Luethi
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6 answers

Time to switch to IPv6?

I am thinking of upgrading our networking situation and am considering a migration of IPv4 to IPv6. Is it too soon to be considering this move as it looks like much of the networking gear and OSen are ready for it? Where do I lose out in such a…
mdpc
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2 answers

What are the differences in the contents of datagrams, frames, and network packets?

I'm reviewing the networking security unit of the class I'm in, and I had a question. I know that datagrams are packets at the transport layer of the OSI model, whilst frames are the name for packets in the transport layer and network packets are in…
Aditi Ramaswamy
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15
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6 answers

Securing OSPF with only passive interfaces

I know that to secure OSPF you should 1) use OSPF authentication, 2) use passive interface command on interfaces that do not have ospf neighbors. If I only use the passive interface command and not ospf authentication, what vulnerabilities am I…
allred
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6 answers

How to factory reset IOS-XR?

I want to factory reset IOS-XR. The router used is ASR9000 I'm used to do that easily in IOS doing config-register 0x2102, write erase followed by a reload. I search on documentation, but found no explicit information. What is the correct method…
cgasp
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15
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3 answers

MPLS vs Encrypted VPNs - traffic security?

Why do people say a lot of times that they have two connections between two offices - the main one being over MPLS and the backup one over VPN. Why not run a VPN over MPLS too? Is MPLS secure? Can no one evesdrop on the traffic?
Yon
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5 answers

How to filter non-bogon prefixes received via BGP from an Internet Exchange(IXP)?

When connected to an Internet peering exchange(IXP), what is a good way to make sure that people don't send you prefixes that they shouldn't be announcing? With regards to bogons I'm aware of the Team Cymru Bogon Reference project but when it comes…
SimonJGreen
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1 answer

Why should the native VLAN never be used?

Currently studying for a CCNA Security, I have been taught to never use the native VLAN for security purposes. This old discussion from Cisco forum states it very clearly: You should never use the default VLAN either because VLAN hopping is much…
WhiteWinterWolf
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15
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2 answers

Why are there 3 ranges of private IPv4 addresses?

Why are there three separate ranges of private IPv4 addresses of different sizes? Why not just reserve the largest (10.0.0.0 - 10.255.255.255) range and let people create /16 or /24 (or whatever) networks within that range if they need smaller…
Adam Sharpe
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4 answers

Finding IP Addresses for Social Network Sites

How do I find out a company like facebook's IP addresses. I am trying to block facebook at work and having some difficulties with HTTPs and URL blocking. Everytime I block a facebook IP more seem to pop up. Is there any easy way to find out all the…
pjf
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15
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7 answers

Quality of Service based on Layer 7 traffic

How can one perform quality of service based on layer 7 traffic? How would you classify the traffic and actively monitor and respond (dynamically prioritizing traffic)? Are there any solutions which provide a kind of weather map?
Lucas Kauffman
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3 answers

Will duplicated MAC address give problems, if in different VLANs?

A small company has 2 Cisco Catalyst 3550, with 24 ports each, connecting their equipaments. After some trouble, we found that two NICs had the same MAC address. After the initial reaction of blaming who bought such NICs, etc., I began to wonder: if…
woliveirajr
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3 answers

What is the purpose of an Ethernet magnetic transformer, and how are they used?

I have been told that Ethernet magnetic transformers are used for base-t Ethernet when transmission is sent over a lengthy cable. What is the purpose of the transformer? (is it for signal filtering or boosting?) Additionally, I have a circuit that…
Benjamin
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