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1500 questions
13
votes
3 answers

Mac-flap due to roaming clients on wireless

We are running an Aerohove wireless network (controller-less).. I occasionally get mac-flaps within the VLAN tied to a SSID. I know this is coming from a roaming client.. The problem is that the company I work for has end to end vlans (no money to…
user209
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1 answer

Why in TCP the first data packet is sent with "sequence number = initial sequence number + 1" instead of "sequence number = initial sequence number"?

In the 3-way handshake, the initial sequence number of both endpoints of the TCP connection is synchronized. Here is an example: Endpoint A randomly generates an initial sequence number: 123. Endpoint B randomly generates an initial sequence…
ilBarra
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13
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4 answers

What is the use of wild card masks vs normal masks

I've always wondered what the use of wild card masks was. When I learned about them in college I wondered what the use was, we saw that you could separate subnets by for instance even and uneven IPs. What is the practical use of wild card masks vs…
Lucas Kauffman
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13
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2 answers

Who has control over allocating MAC address to device manufacturers?

As of my knowledge each MAC address is unique for each device like servers, computers, firewalls, switches and routers, proxies, etc. So my question is: who is responsible for allocating these MAC addresses to the device manufacturers?
user73764
13
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5 answers

ASA 5550 - Reboot Worthwhile?

I've got an ASA 5550 that is performing loads and loads of operations (AnyConnect, NAT, ACL, RADIUS, etc, etc). It isn't particularly overloaded in terms of CPU & Memory, but it has an uptime of over 3.5 years. Lately I have been attempting to…
BrianK
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13
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2 answers

Why does Ethernet use EtherType field to determine what type of packet is in a frame instead of just looking at the packet header?

I'm studying for some networking concepts and have learned that a receiving host looks at an Ethernet frame's header to determine what protocol being used by the packet. It makes me wonder though, since a packet header includes this same info, why…
ComputerWhacker
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13
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3 answers

Why is symmetric NAT called "symmetric"?

After searching a while, I'm still not able to find a logical explanation on why is it called symmetric NAT. Where lies the link between symmetric NAT and that each request is mapped to a unique external source IP address and port? Is there any at…
marc
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13
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4 answers

Difference between :: and ::1

I am confused about following netstat output. There are two kind of local ports. The first is: [::]8100 The second is: [::1]8100 I know that [::1] is a loopback address for IPv6. My question is: What does [::] mean? Thank you in advance for your…
Dadash Memmedli
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13
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3 answers

What is the least possible separation of two NICs with the same MAC address?

Suppose you have two NICs with the same MAC address, but not necessarily the same IP address. What is the least possible separation (in terms of number of switches, routers, different IP subnets etc.) needed that would still allow traffic between…
LapplandsCohan
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13
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4 answers

How can I formulate the communication latency in TCP/IP?

I have difficulty in deriving a mathematical model/equation to estimate the round trip latency between two nodes communicating using TCP/IP. The nodes are exchanging data based on HTTP protocol. In this model, the most important factors to study are…
Espanta
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13
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6 answers

How does BGP work over TCP?

As far as I know we are using routing protocols to achieve Layer 3 connectivity, I am confused with the fact that BGP works over TCP which is L4. How can L4/TCP be established without prior L3 connectivity?
blended
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13
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1 answer

What is the 5 level QoS model (through config example)?

I have heard people stating that their network "operates a 5 level (or layer) QoS model" Sometimes they also mention a 7 level QoS model. Can anyone provide me with a Cisco IOS config example of what is meant here. So by this I mean a config…
Baldrick
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13
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2 answers

Switchport in half duplex - Download speed suffering but upload was fine

A user had issues with download speed from the Internet. The connection to the Internet is 100 Mbit/s. The user got around 7 Mbit/s downstream and around 80 Mbit/s upstream. I tested from my computer and it got around 70 Mbit/s downstream and 80…
Daniel Dib
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13
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2 answers

10GBase-T vs. SFP+ Direct Attach

What are the advantages and disadvantages of using 10GBase-T vs. SFP+ Direct Attach to interconnect devices where distance is not a determining factor?
sardean
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13
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4 answers

Hardware tap vs port mirroring - Any limitations?

I predominantly work in a Cisco environment and contemplating buying a network tap device for use with Wireshark. Can anyone provide the pros and cons from their experience between using network taps OR setting up port mirroring given considerations…
MattE
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