TCP/IP

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Transmission Control Protocol/Internet Protocol (TCP/IP) is the set of networking protocols that define end-to-end connectivity specifying how data should be packeted, addressed, transmitted, routed and received at the destination. This functionality is organized into four abstraction layers which are used to sort all related protocols according to the scope of networking involved.

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When you are running iSCSI, is TCP sliding window an important consideration? The situation is is Cisco UCS fabric interconnect to a Nexus 5k switch. The switch frequently drops packets inbound from the UCS and this appears to be an issue iSCSI frames from UCS being 1514 bytes which the interface on the Nexus is 1500 and jumbo framing is not enabled. I don't know why the vast majority of frames make it on through yet a significant number (in the millions) are dropped.
The port channel spikes up to about 10Gbps and most of that will be iSCSI. So the connection initiator to target works for the most part. I've planned to enable the jumbo frames as recommended by Cisco so that the 1514 iSCSI will be better processed and not dropped.

But my question is this: With iSCSI, are TCP conversations lengthy or very brief? To what degree would some dropped frames (.003%) in-path cause an issue for iSCSI TCP conversation? Or would this percentage just be noise that TCP connection orientedness should just deal with?
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8 Comments
Is pipe.exe something to remove and if so, how do I remove it?  Was watching TCP connections in Resource Monitor and saw that. It has an IP of 158.69.158.96.  Anyone know what that is?
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2 Comments
What is stateful and stateless connection? I got to know TCP is stateful connection while HTTP is stateless. Though HTTP is L7 and TCP is L4 protocol and HTTP in turn uses TCP protocol. So how it is going to work? a stateless protocol over stateful protocol.

so if we need to configure a failover mechanism then which protocol is better? stateful or stateless? I really would like to read more about it on how it works. Thanks!
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2 Comments
I added a network printer on my pc as tcp/ip printer .. the next day the port name changed to the name of the printer and in the IP address field also I found the printer name . I tried to ping the printer by its name and I failed then I deleted the port and added a new tcp/ip port and it worked again . my question is why the port configuration got changed I mean the IP address in the port configuration got changed to the printer name . is it from WSD (the discovery port) on the printer properties?

note: the printer is also installed on a domain server and listed in the directory and shared from it. but in my pc  I added it as network not as shared printer.

 printer.png
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3 Comments
Hi,

I started with this:
http://www.macinstruct.com/node/550

but when i completed this i had no internet connection.

ive done the basics, eg disable/enable and reboot. help!
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3 Comments
On internal intranet the C/C++ client sends out REST-like queries via TCP/IP and receives an XML response from the Java server. If the REST query loops fetching 3 records at a time, the total time to accumulate 90000 records is about 10x longer than if we fetch 100 records at a time. We will be performing a number of timing tests to isolate the cause. In anticipation that the problem may be the slow TCP/IP start due to initial small windowing, what settings are there to tell TCP/IP to start off with the largest (or larger) window size possible?

We are on 64-bit RHEL servers, and I assume that since the client/server are run on an intranet self-contained within the company, that we do not have to be concerned about congestion.

Thanks,
Paul
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12 Comments
Hi! i am currently using classA network and run out of ip. how can i extend to get more ip.
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11 Comments
Hi, if i have subnet mask 255.255.255.0  is that mean i have ip address from 192.168.1.1 to 192.168.1.254. Say if i use class b 255.255.0.0 is that mean i can use ip from 192.168.0.1 to 192.168.254.254?
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3 Comments
I'm using Ubuntu and I have a C++ application which uses WxWidgets and sends a string over TCP several times. It works pretty fine only if the router and the connection are OK, otherwise it gets stuck and I need to manually quit the application.
I would like to send the data without blocking the application flow in case of errors.

I call the function in this way:

    
 SendCommand ptr;
    if ( ptr.sendcommand(16,16,1) ){
    printf("Porta Aperta\n");
    } else {
    printf("Errore di comunicazione - porta non aperta\n");
    }

Open in new window


and this is the function:

int SendCommand::sendcommand(int relay_on, int relay_off, int stop){
    printf("eseguo la funzione nella classe\n");

    std::array<uint8_t, 8> command1;
    std::array<uint8_t, 8> command2;

    switch(relay_on){

    case 16: command1 = {0x58, 0x01, 0x12, 0x00, 0x00, 0x00, 0x10, 0x7B}; // switch on the relay 16
    break;

    }

    switch(relay_off){

    case 16: command2 = {0x58, 0x01, 0x11, 0x00, 0x00, 0x00, 0x10, 0x7A}; // switch off the relay 16
    break;

    }

    int sockfd, n;
    struct sockaddr_in servaddr;

    std::string serveraddr = "192.168.1.4";

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if ( sockfd < 0 )
    {
        cerr << "Error creating socket! " << strerror(errno) << endl;
        return -1;

    }

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = inet_addr(serveraddr.c_str());
    servaddr.sin_port

Open in new window

…
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5 Comments
FileZilla-Server-Connection-Issues-.docxFileZilla Server SFTP connection issue from outside network. I need help resolving issues with sftp connection to filezilla server from outside network. Please see attachment for details for my current Router, FileZilla Server, and FileZilla Client configurations.
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7 Comments
Hi,

I just enabled DNS-Over-HTTPS in my google chrome and wanted to know how to set it in the iPhone/iPad.   Haven't been able to do ti; how can I enable DoH in my iPhone/iPad?
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15 Comments
I have (2) Watchguard M270's configured in a firecluster.

Interface 0 is the External interface configured with a /28 block.
Interface 1 is the LAN

We have consumed all of our IP's so I ordered another /28 block from our datacenter today. As soon as I configure Interface 2 for our new IP block, outbound traffic for the most part ceases to work on our network, however some things do work.. so we'll call it intermittent. As an example, I can ping out to 4.2.2.2 but can't ping 8.8.8.8. As soon as I disable Interface 2 that is configured for the new IP block, I am able to ping 8.8.8.8 again.

I'm assuming this is because we now have 2 WAN interfaces configured and outbound traffic doesn't know which interface it should be sending traffic out on but I couldn't be sure. I've made 4 calls to Watchguard support and nobody can identify the problem. I even had our datacenter issue us a different IP block just to rule out any kind of odd conflict but the problem persists with a new IP block.

Am I going about this all wrong trying to have 2 IP block's configured on our Watchguard? Is the better solution to just order a bigger block of IP's and re-IP everything? I was trying to avoid that hassle by just adding an additional block of IP addresses but it seems that what I'm trying to do here isn't working..

I would appreciate any advice or input that someone could give on this. Thank you!!
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1 Comment
Hello,

My site has not stopped planting for a while.
I was advised to check my logs and I see that there is this IP 150.918 times in my logs from 00:00:07am to 12:36:01am

ip.png
what do you advise me to do?

I added this Deny from 104.248.248.206 to my .htaccess but ip continues to show...

Thank you for your advice,
Jaber
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14 Comments
I have an electronics board which has 16 relays and it works over TCP/IP.
The IP address of the board is 192.168.1.4 and the port is 3000.
I would like to control it with C/C++ under Ubuntu.

There is a list of HEX commands that it is possible to use in order to remotely switch ON and OFF each relay on the board.
This is the list:
"580112000000016C",  // switch on the relay 1

"580111000000016B",  // switch off the relay 1
"580112000000026D", // switch on the relay 2
"580111000000026C", // switch off the relay 2
"580112000000036E", // so on..
"580111000000036D",
"580112000000046F",
"580111000000046E",
"5801120000000570",
"580111000000056F",
"5801120000000671",
"5801110000000670",
"5801120000000772",
"5801110000000771",
"5801120000000873",
"5801110000000872",
"5801120000000974",
"5801110000000973",
"5801120000000A75",
"5801110000000A74",
"5801120000000B76",
"5801110000000B75",
"5801120000000C77",
"5801110000000C76",
"5801120000000D78",
"5801110000000D77",
"5801120000000E79",
"5801110000000E78",
"5801120000000F7A",
"5801110000000F79",
"580112000000107B",
"580111000000107A",
"5801130000FFFF77",
"580113000000007B",
"5801100000000069"

I'm correctly able to switch on and off each relay by sending command line commands under Ubuntu:

echo '580112000000016C' | xxd -r -p | nc 192.168.1.4 3000

Open in new window

The above code correctly turns on the relay.

I would like to do the same with C/C++ code since I want to control the …
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23 Comments
I have 2 PCs that are both connected to the same WiFi network.  Both PCs are on the same work network, both have the same workgroup name and I have toggled network sharing off and on - on both of the devices.

Neither can ping the other.  However, where it gets strange here... If I run simultaneous cmd pings of each other, #1 PC starts successfully pinging the other, but stops if I stop the ping attempts from the other PC to it.  #2 PC pings never resolve.

Both devices are Dell Optiplex 3030AIO and on Windows 7 Pro, Service Pack 1
Recording--1.mp4
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7 Comments
Hi,

All the Servers are in Data Center (Colo).
I want to go remotely to all the Controllers (including IDRAG) which are in Colo.

Question: What command would I use to get the above IP addresses?

Thanks,
tjie
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4 Comments
I'm having issues finding IP address design plans to implement in a newly deployed network.  Running BGP at the Edge and OSPF as an IGP.  Any assistance is greatly appreciated.
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6 Comments
I have two NICs, one is cabled directly into a server, and the other goes through a Sonicwall and out to the internet where it sends and receives files from a central portal.

The NIC to the server is working fine.

The NIC to the internet is saying "Limited" and I cannot get full connectivity for that NIC, can anyone please advise on how to troubleshoot a NIC that is giving this error
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14 Comments
My network is not allowing me to see all the network devices using windows 10, I see some of the devices.  My MAC however see all the Network devices.  I have a server WIN 2012 server and it see some of the devices in the network.  We are using a Workgroup environment connect to Office 365.  Some machines are connected to the Work and School and some are not.
My main problem is a NAS server that is on the same subnet but I cannot get it to be discovered when I use the IP address of the NAS server?  I have 2 NAS servers and both are very difficult to connect to?   I took over this network and the previous Admin used a lot of VLAN configurations, can he controlled the network using th vlan on the switches?

I looking at the router, I looking at the switches....I not sure where exactly to start and try to identify the lag in the network and why I cannot see the other devices?
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3 Comments
Can someone help me determine how to find out where the IP address of 10.1.1.115 lives on my network. It appears to be a webpage. I'd like to turn it off with the abillity to turn it back on, then see if anyone complains that they are missing something

Message meets Alert condition
Virus/Worm detected: HTML/Framer.INF!tr Protocol: "HTTP" Email Address From:  Email Address To:
VIRUS REFERENCE URL: http://www.fortinet.com/ve?vn=HTML%2FFramer.INF%21tr
date=2019-08-02 time=09:04:13 devname=FG-Corporate devid=FG100D3G14808552 logid="0211008192" type="utm" subtype="virus" eventtype="infected" level="warning" vd="root" eventtime=1564751053 msg="File is infected." action="blocked" service="HTTP" sessionid=106413455 srcip=10.1.1.115 dstip=208.91.196.145 srcport=49975 dstport=80 srcintf="lan" srcintfrole="undefined" dstintf="wan1" dstintfrole="undefined" policyid=92 proto=6 direction="incoming" quarskip="File-was-not-quarantined." virus="HTML/Framer.INF!tr" dtype="Virus" ref="http://www.fortinet.com/ve?vn=HTML%2FFramer.INF%21tr" virusid=8054799 url="http://ww1.useyourinterface.com/" profile="default" agent="Mozilla/5.0" analyticscksum="0a449968f2e6c0c358cecf9365b94041399735926a25573e1e37fbdb4e741f05" analyticssubmit="false" crscore=50 crlevel="critical"
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9 Comments
We have multiple sites all on different subnets, we have one central DHCP server which I want to change (so I can do maintenance).

I want to add a second DHCP server (for redundancy) but I can only broadcast one helper address from the site routers.  I have read up on virtual IP's but am unsure if this is the correct way to go.

Notes.
We have multiple DC's in different geographical locations
Routers are part of our MPLS so I cannot make changes (I can have the helper add changed)
All servers are in the hosted data center (VM's)

All help/advice gratefully received.
Steven
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16 Comments
Usage of Update-Source Loopback X

I have seen in BGP configuration where they configure : Neighbor x.x.x.x remote-as x  Update-Source Loopback X
Even if there is only one path to reach the neighbor
for instance in the topology below, let's take R5 with R1 as example:

R5: Neighbor 1.1.1.1 remote-as 1 update source loopback 0

instead of Neighbor 51.0.01 remote-as 1

assuming R5 s1/0= 51.0.0.5/24 and R1 s1/2 =51.0.0.1/24

Thank you

bgp.JPG
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2 Comments
BGP Configuration with and without another IGP

in the topology below, I would like to know if :

-- BGP needs to be configured on R1  R2,R3,R4  without any other IGP (OSPF)configured on the same routers.
-- Or BGP can be configured only on R1 and R4, but IGP (OSPF) should be configured on all 4 routers R1,R2,R3,R4

Thanks


b
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5 Comments
OSPF Address-Family

I have seen  in some examples EIGRP configured with   address-family ipv4 vrf <VRF Name>  autonomous-system <AS Number>
However I have not seen examples where OSPF  is configured with  address-family ipv4 vrf <VRF Name>

for instance, in the topology below Customer Edge CB_1 uses OSPF  and  it is connect to PE_1

Thanks

m
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4 Comments
Configuring BGP at the Customer Edge Router

knowing that Customer Edge routers cannot contain in their tables all BGP routes available in the Internet, so how are those Customer edge routers configured to reach Internet without having to have full internet routing table

Thank you
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3 Comments

TCP/IP

11K

Solutions

6

Content

i
The collection of articles, videos, and posts on this topic.

17K

Contributors

Transmission Control Protocol/Internet Protocol (TCP/IP) is the set of networking protocols that define end-to-end connectivity specifying how data should be packeted, addressed, transmitted, routed and received at the destination. This functionality is organized into four abstraction layers which are used to sort all related protocols according to the scope of networking involved.