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1500 questions
16
votes
2 answers

What is this device used by a networking technology company?

I recently saw two men open up the sidewalk in a major German city. It seemed they dug out this device Both men worked for a networking technology company, so I hope this is on topic here. What is this device?
Stefan
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3 answers

Is it possible to specify a route for a packet to take?

So, AFAIK, packets "hop" between routers. Packets are forwarded via a router's default path until it gets to destination IP. So is it possible to specify a specific set of routers this packet "hops" to?
lpydawa
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16
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5 answers

How can I reset a VPN tunnel on a Cisco ASA?

On a site-to-site VPN using a ASA 5520 and 5540, respectively, I noticed that from time to time traffic doesn't pass any more, sometimes just there's even missing traffic just for one specific traffic selection / ACL while other traffic over the…
Stefan
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16
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2 answers

Router won't hold configuration

I have reset the password on a Cisco 1700 router, now when I copy run start or write mem then reload or reboot, it defaults to factory settings, i.e. it is not holding the configuration I have just written. To reset the password I used the boot from…
Andy Mac
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16
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4 answers

Why is 10.1.255.255 an invalid broadcast address?

I’ve been following the CCENT official certification book(100-105) and came upon this question in the “do I know this already?” quiz. The books only covered /24 subnetting only so far. Which of the following is a network broadcast address? a.…
Bilal Baroudi
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16
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5 answers

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 collision in an upper level (two frames collide…
Christos Dalamagkas
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16
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7 answers

Automate configuration backup (every minute) in Cisco IOS

I'd like to make my Cisco router automatically do a copy run TFTP (and populate the fields automatically) every 1 minute. I'd also like it to be run in the background. Anyone know if this is possible/how to do it? I'd like to do this for the sake of…
Michael May
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16
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5 answers

Do Wi-Fi and IEEE 802.11 mean the same thing?

I would like to know if Wi-Fi can be generally referred to as the IEEE 802.11 standard or if the latter is a more general family.
Abdulhameed
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16
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2 answers

Network Gateways vs Interfaces

When looking at the contents of a routing table section on the Wikipedia article on Routing Tables, it contains a table as an example of a routing table with two headings which have an unclear distinction to me: Gateway and Interface. I believe a…
Alex W
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16
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8 answers

Does TCP open a new connection for every packet that is sent?

This might be a silly question but a me and few buddies have been discussing the potential limitations of TCP. We have an application that is going to listen for clients (think of a gateway) and route all connected clients data through a single…
user0000001
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16
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1 answer

Should ARP requests be VLAN tagged?

I'm wondering if the ARP requests should be tagged when being sent out of a VLAN tagged interface? It seems logical to me that the ARP request should be tagged, since it needs to travel all the broadcast domain. If any switches or devices in the…
Simon
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16
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3 answers

Why would a switch be connected to a router using three ethernet cables?

In our rented office, we have a router (BT smart hub) connected to a large switch (model unknown). The two are connected using three ethernet cables, thus: ----------------------- | 1 2 3 4 Router | ----------------------- | | | | |…
EvilDr
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16
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3 answers

mtr output with high packet loss on one hop

I'm investigating a complaint of poor performance from an end user accessing a site I help maintain. I have these two mtr outputs to the end user, the first from the site: Packets Pings Host …
MikeyB
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16
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3 answers

class-default matches control traffic?

I'm seeing an issue with BFD on a link that's being policed egress where it appears during times where the policer is maxed BFD packets are not getting to the other side. I'm wondering if BFD hellos are subject to the policer or if they fall…
Mud
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16
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3 answers

DWDM active and passive comparison

I am trying to understand the cross-over point for when I would deploy active DWDM over passive DWDM (as active seems to be more expensive based on my initial research); Passive DWDM takes in various colours / wavelengths and muxes them onto a…
Baldrick
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