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Posts published in “Computer & Internet”

Does Ethernet still use CSMA/CD?

So considering that CSMA/CD is for detecting collisions, mostly in a bus scenario with a lot of stations, then is CSMA/CD still used?

Because right now most of the connections are point to point (for example one router getting connected t...

Which regex flavor is used in the Junos CLI?

I'm trying to do some regex matching in the Junos CLI, like show configuration | match "fancy.pants(reg|ex)". I especially want to look for word boundaries and other character classes. I'm used to \b, \d, etc. in PCRE-ish regex, and that d...

Ethernet’s frame format, length or EtherType?

Ethernet defines a 2 byte header for the payload's length in its frame format.

This header has an ambiguous meaning:

if smaller than or equal to 1500 it represents the payload length.

if greater or equal 1536 (0x600) it is to be con...

Is QoS an issue for VOIP calls over the Internet? If not, why not?

I'm trying to decide whether I should buy SIP trunks from my ISP or a 3rd-party.

As I understand it, it's important to maintain QoS on an internal network (i.e. prioritize VOIP traffic). Is this not also true on a public network?

My ISP ...

How to flush route cache in fortigate

Is there something like route cache on fortigate like in linux?
How can i clear this cache?

I have some problems with OSPF, after adding or changing redistributed network. Foritgate show routes correctly but traffic from some hosts is go...

What are the reasons for seeing an incomplete ARP?

As was mentioned in this post:

The reason for seeing an incomplete ARP is that "An ARP request was sent for that address, but the host with that address is not up and running on the LAN, so there is no reply"

So, if a multilayer switch ...

Empty mac address value [closed]

Is there some MAC address value, that can be used to denote that device does not have MAC set (something like 0.0.0.0 for IP).? I thought of ff:ff:ff:ff:ff:ff, but afraid that it could be meaningful when set for interface.

The question is...

What is "cflow" in ipfix?

I am learning ipfix and found a cmd like this:

tshark -r ipfix.cap -n -d udp.port==4379,cflow -O cflow

What does the cflow part mean here?

I was also told to filter cflow if I use Wireshark in Windows.