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1500 questions
6
votes
6 answers
Why doesn’t ICMP use port numbers?
Firewall is showed in port no 7 and Google search is also showed in port no 7 so I am confused about how exactly ICMP use the port number.
Regards,
Bhushan
Bhushan Wankhede
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6
votes
2 answers
Cisco 6509 Supervisor Card Slot Boot Failure
We recently had a sporadic reboot of a distribution switch for an unknown reason. No recent hardware/software changes have been made. Our log files don't indicate anything leading up to the incident.
The system is a 6509-E running software version…
Ryan Foley
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6
votes
2 answers
SPAN impact on ASA performance
I am planning to mirror some traffic on an ASA 5510 running version 9.1. this traffic is mostly internet data which cannot exceed 30 Mbps.
what impact could this SPAN operation cost me on performance ? and is there any security concerns when trying…
Hamdi Kadri
- 147
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6
votes
1 answer
Does TCP Cwnd keep increasing if transfer is limited by Rwnd?
I'm trying to understand what happens to the TCP Congestion Window (Cwnd) if the transfer rate is limited by the Receive Window (Rwnd). I know that the transfer rate is the minimum of Rwnd and Cwnd. I also know that Cwnd increases for each ACK…
EM0
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6
votes
1 answer
Cisco Nexus 3064PQ CPU spike causing packetloss
Nexus 3064 CPU spike and packetloss
I have L3 Cisco 3064PQ switch which is running latest "nxos.7.0.3.I4.7.bin" basically I am using for routing so my ISP 2x10Gbps link terminated (with LACP) on single switch (without STP,vPC) it and currently live…
Satish
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6
votes
3 answers
Cisco ASA 5510 - ACL Config Question
My company's email server is under attack from the following IP address blocks
92.63.193.0
5.188.9.0
Here are the corresponding WHOIS records for each network
% This is the RIPE Database query service.
% The objects are in RPSL format.
%
% The RIPE…
Richie086
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6
votes
3 answers
Why couldn't a nework address be used as as broadcast address as well?
I am taking a refresher on Networking and I found out that:
Network address is an IP address with all 0s after the subnet mask
Broadcast address is an IP address with all 1s after the subnet mask
What is the point of reserving two IP addresses in…
Alex
- 163
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6
votes
1 answer
Wireshark TCP and window size
Can please someone explain me on the below screenshot why host 192.168.1.200 on packet 9 sends an ACK for the packets 6 - 7 - 8? The total packet size does not correspond to the window size agreed. If I understood it correctly the window size is the…
user3249
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6
votes
3 answers
When is 'Timestamp' and 'Timestamp Reply' are used in ICMP protocol?
I started the packet capture in my laptop through Wireshark application.
Now through cmd, I pinged some server (say, www.google.com).
And i stopped packet capture and analysed the packets being capture corresponding to the ping operation.
Packet…
Deepak
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6
votes
3 answers
Is UDP Usage in Routing Information Protocol (RIP) a Secure Practice?
I know that UDP is a connectionless transport layer protocol. Since it is easy to fake your source IP and source Port in your headers, what keeps anyone from poisoning routing tables via RIP? It seems to me like I can easily flood routers with fake…
Ninja Bug
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6
votes
1 answer
2960X Management VLAN
I have a Cisco ws-c2960x-24td-l running 15.2(2)E7
I have created a management vlan (500) and want to put the management interface (FE0) into it, however the "switchport" command is not available for this interface.
Can somebody let me know what I am…
B. Austin
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6
votes
1 answer
Cisco 1200 AP, client information from CLI
I'm working with several cisco 1200 series APs, trying to get relevant client information off of them. It would be helpful to see RSSI and SNR for individual clients connected, but I am unable to find any commands that are related to this. I've…
walkerboh8806
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6
votes
1 answer
What's the domain of an IP?
CIDR stands for "Classless Inter-Domain Routing". But what's a domain in this case? Seems to not be the same kind of domain as DNS deals with...
lindhe
- 163
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6
votes
1 answer
802.11ac: What is the benefit of MU-MIMO?
Say you have a 3x3 AP and three clients.
Without MU-MIMO, one client can receive three spatial streams per time slot.
With MU-MIMO, three clients can each receive one spatial stream per time slot.
However, the total link capacity per client is still…
elin05
- 517
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6
votes
3 answers
How to view MTU size in Wireshark?
I've been reading about maximum transmission unit (MTU) which is the size of the largest protocol data unit (PDU) that can be communicated in a single, network layer, transaction.
I'm generating a few network traffic right now and capture it in…
Sabrina
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