Questions tagged [tcp]
For questions about Transmission Control Protocol (TCP), a transport protocol used to encapsulate data across a network for reliable communication.
792
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RFC4821 PLPMTUD probe request
PLPMTUD - Packatization Layer Path MTU Discovery
Subsequently increasing MTU probe requests are sent to measure optimal MTU till one fails.
Does the probe request contain actual data to be sent? OR ...
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3
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What is the difference between MSS and MTU?
I'm confused as to the difference between maximum segment size and a maximum transmission unit.
Can someone please explain in relation to layers 2 and 3?
If I had a packet of 800 bytes in the ...
- 631
2
votes
1
answer
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How many handshakes for parallel http connection?
HTTP uses TCP for its transport protocol. Hence, a three-way handshake is performed before a connection is established. What if there are parallel HTTP connections? Must a three-way handshake must be ...
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6
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1
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Wireshark tcp.len and data.len missmatch
What is the difference between tcp.len and data.len filters? I thought that both mean data size traveling in the segment (not including TCP header). I have a problem related to MTU issue and I'm ...
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7
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1
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tcp.length and tcp.data wireshark filters
I was playing with Wireshark and noticed two filters: tcp.len and tcp.data. What is the difference between the two? As far as I know, the tcp.len (length) field tells how many bytes of data travel ...
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4
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How is TCP duplex if Ethernet is half-duplex?
If I understand correctly, TCP is a full-duplex birectional protocol. However, Ethernet is half-duplex.
Does this mean that eventhough TCP supports full-duplex, it only operates in half-duplex mode ...
- 151
14
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1
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Why BGP implements its own keepalive instead of using tcp keepalive?
BGP doesn't use TCP keepalive, it uses its own keepalive mechanism. My question is why can't bgp turn-on the SO_KEEPaLIVE of TCP and live happily? why does it not use tcp keepalive and implement its ...
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TCP connection stalling [closed]
With these two captures in mind (both illustrating the problem) we are experiencing a problem with TCP flow when we have some specific packet loss.
https://www.cloudshark.org/captures/a1a050d95269 (...
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3
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2
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VPN cisco ASA tcp connection issue -pcap inside
I have set up a VPN between my company and a customer. Packet captures show that the customer receives a packet and then sends an ACK back as it hits our internet firewall, this is as far as the ...
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1
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Ttcp specific question
A TCP server has IP address 10.0.7.2 and a TCP client has IP address 10.0.7.3. The TCP server is waiting on port number 3333 for a connection request. The client connects to the server and transmits ...
4
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2
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Implementing the TCP Authentication Option (TCP-AO)
Do any Cisco IOS/XE/XR systems support the updated TCP security option TCP-AO (option kind 29)? It'd be nice to be able to use it.
It's defined in RFC 5925, and is meant to obsolete RFC 2385, "...
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3
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Reliablity vs unreliable service at IP and Link Layer
I am taking about the 5 layer model. It is well documented that TCP is a reliable service and IP is best-effort delivery and hence unreliable (ref RFC 792 - TCP). Also, the data link layer is '...
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3
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How can a TCP socket be identified by IP address?
This is from the book: "Computer Networking - A Top Down Approach" :
One subtle difference between a TCP socket and a UDP socket is that a
TCP socket is identified by a four-tuple: (source IP ...
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13
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6
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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 ...
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Does TCP use Virtual Circuit Model?
First some information:
In virtual circuit model ( which is in the Network Layer ) there are three phases:
1) Connection establishment => In this step a path is chosen. Let's simply say, use ...
- 283
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1
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Dropped data packet on satellite connection
We have several embedded pcs on farms in the UK and US. Among other connections these talk to our server sending a small packet of data (100 - 600 bytes) every 20 seconds.
Over DSL this is fine. ...
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3
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How HTTP is converted to TCP and then how TCP converted to IP?
I know that in Internet Protocol Stack there are actually three layer. They are Application, Internet and Transport. Let's say HTTP in Application layer will be converted to TCP in Transport layer and ...
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3
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Sending generic UDP traffic for Network Simulation
I need to test an application which drops a user-specified percentage of packets. Right now, it will drop any packet type which I can easily verify by sending pings and observing the ICMP messages in ...
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Traceroute Over TCP vs UDP
For what purpose would one wish to send traceroute over TCP rather than UDP? What advantages/disadvantages are there in doing so? I know that traceroute normally uses UDP ICMP "echo" packets while ...
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1
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1
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What happens when TCP Sequence Number is incorrect?
Let's assume that A is connected to B, and A has received 100 bytes until now. So, the next packet he will receive should have a SEQ number of 100 or a little more if the packets don't reach A in ...
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1
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1
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Why do not we have checksum validation in the application Level (BGP , RIP)?
In BGP, TCP handles the checksum and BGP does not perform any checksum validation in the application level.
How can we believe TCP must forward the data without errors?
Similarly in RIP with UDP ...
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2
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1
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1k
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Why am I having issues accessing a website hosted on servers behind a load-balancer?
I am having an issue with an offsite location accessing a website that is hosted on 3 servers behind a Coyotoepoint Load-Balancer, at our Corporate Office. We currently have well over 500 locations ...
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1
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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 ...
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2
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Which interface will TCP choose for redudant connection between two routers?
|------------1 same cost----|
Router 1| | Router 2
|------------2 Same cost----|
If we have a ecmp link between two routers using which interface a TCP connection ...
- 1,124
0
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1
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TCP/IP Header compression
I'm reading RFC 1144 and I'm trying to figure out how the TCP/IP header compression works. As I understand it, the sender only sends a couple of fields that are likely to be changed.
If the packet ...
- 135
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1
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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 ...
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2
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How does nmap distinguish closed ports from filtered ports
Let's suppose we are doing a TCP connect scan.
a nmap scan on google returns the following output :
PORT STATE SERVICE
80/tcp open http
443/tcp open https
However, if I try to ...
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1
vote
1
answer
841
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Why don't I see client-to-server TCP traffic when sniffing iPerf TCP throughput?
When I do an Omnipeek capture of an iPerf TCP throughput test over WiFi, I only see TCP Acks from the iPerf server to the client. How come I don't see any TCP frames from the client to the server? I ...
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Wifi TCP iperf throughput: 1 stream vs multiple streams?
In a WLAN iperf TCP throughput test, multiple parallel streams will give me higher throughput than 1 stream. I tried increasing the TCP window size, but I still cannot achieve the max throughput with ...
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7
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2
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F5 session timeouts
Our F5 load balancers run version 10.2.4. We migrated from Cisco load balancer cards on the Catalyst 6500 and used to be able to run xterm sessions to our solaris and linux servers without the ...
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5
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Packet sizes in a TCP stream
I'm network traffic and wish to divide each TCP session into a series of requests and responses (the protocols I'm working with all work that way, like HTTP or SSL).
I had a simple assumption (...
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3
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2
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158
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Is application level re-transmission needed for TCP and SCTP
I am trying to develop a server-client paradigm based application suite. I am planning the app to work with both tcp and sctp protocol support. Now my question is if any of the TCP/SCTP packet is lost,...
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7
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Redundant IP link aggregation for failover operation without route failure detection
I am looking for a technology to achieve TCP connection fault tolerance with the help of two links between hosts and without time delays for route failure detection. Something like this:
...
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3
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1
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TCP Vegas algorithm description
I am making a paper about the different congestion avoidance protocols of TCP and one of them is the TCP Vegas. I have searched a lot on internet about how it's work but I have some questions. If I am ...
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4
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Does physical distance affect download speed?
I just had an argument with a colleague of mine and thought I'd just reach out to the experts on this. Here's the scenario. We were using a website that measures your connection's speed. We tested ...
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13
votes
2
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Open a range of TCP ports in Cisco IOS NAT
ip nat inside source static 192.168.1.10 10.10.10.9 route-map RANGE
!
route-map RANGE permit 100
match ip address 102
!
access-list 102 permit tcp host 192.168.1.10 range 3000 3389 any
The ...
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votes
10
answers
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Why only port 80 for web services?
Why isn't it sensible to dedicate more than one TCP/IP port to http? Although admittedly naive, isn't it intuitive to think that server performance could somehow be increased?
- 1,041
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2
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How do the Application, Presentation and Session layers of the OSI model map to TCP/IP's Application Layer and vice versa?
I need to map TCP/IP protocols to the OSI model for some university test revision I am doing.
I was wondering if it is generally acceptable to assume any OSI Level 7, 6 and 5 protocol will be ...
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7
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TCP acceleration over satellite or high latency networks [closed]
What viable companies, products or options are out there today for TCP Acceleration over satellite or high latency IP networks?
The average satellite RTT is upwards from 600ms (depends on the ...
- 2,535
3
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1
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UDP Message Length Field and Pseudo Header
I'm learning some tcp/ip basics, and am having trouble understanding the Message Length field in UDP. In my book, it says that the Message Length represents the UDP header and data in octets, and ...
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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 ...
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Is TCP maximum segment size (MSS) "clamping" compatible with IPv6?
With IPv4, TCP MSS "clamping" (a network device editing the MSS value in a TCP header) can help when path maximum transmission unit discovery is not working. (e.g., when ICMP is being blocked ...
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