caur kuru portu iet ping?

[Kolipoki]

caur kuru portu tad iet pingoshana?

kad pingo kaadu IP cauru kuru portu vinjsh cer sanjemt signaalu no taas kastes kuru pingo?

[kiwi]

caur kuru portu tad iet pingoshana?

kad pingo kaadu IP cauru kuru portu vinjsh cer sanjemt signaalu no taas kastes kuru pingo?

 

Ne caur kuru portu kā tu to domā. Ping izmanto ICMP protokolu un iet caur to.

[Kolipoki]

caur kuru portu tad iet pingoshana?

kad pingo kaadu IP cauru kuru portu vinjsh cer sanjemt signaalu no taas kastes kuru pingo?

 

Ne caur kuru portu kā tu to domā. Ping izmanto ICMP protokolu un iet caur to.

vari paskaidrot luudzu drusku smalkaak....?

[josi]

Ja gribi sīkāk, tad iesaku iepazīties ar zemāk minētajiem dokumentiem

 

[iEN 212] IP - Local Area Network Addressing Issues.

[RFC 760] DOD STANDARD INTERNET PROTOCOL.

[RFC 777] Internet Control Message Protocol.

[RFC 792] INTERNET CONTROL MESSAGE PROTOCOL.

[RFC 816] FAULT ISOLATION AND RECOVERY.

[RFC 844] Who Talks ICMP, too? Survey of 18 February 1983.

[RFC 1108] U.S. Department of Defense Security Options for the Internet Protocol.

[RFC 1256] ICMP Router Discovery Messages.

[RFC 1393] Traceroute Using an IP Option.

[RFC 1435] IESG Advice from Experience with Path MTU Discovery.

[RFC 1788] ICMP Domain Name Messages.

[RFC 1940] Source Demand Routing: Packet Format and Forwarding Specification (Version 1).

[RFC 2521] ICMP Security Failures Messages.

[RFC 2765] Stateless IP/ICMP Translation Algorithm (SIIT).

[kiwi]

vari paskaidrot luudzu drusku smalkaak....?

 

Saproti ir dažādi protokoli tīklos' date=' katram sava specifika. Aplikācijas var izmantot dažādus protokolus un ne visiem protokoliem ir porti. Šādu bildi esi kādreiz redzējis?

 

[img']http://www.cisco.com/univercd/illus/i/01/ith2801.jpg[/img]

 

Palasies šeit sīkāk, ja zini angļu mēli

http://www.cisco.com/univercd/cc/td/doc/ci.../ito_doc/ip.htm

 

Internet Control Message Protocol (ICMP) 

The Internet Control Message Protocol (ICMP) is a network-layer Internet protocol that provides message packets to report errors and other information regarding IP packet processing back to the source. ICMP is documented in RFC 792. 



ICMP Messages 

ICMPs generate several kinds of useful messages, including Destination Unreachable, Echo Request and Reply, Redirect, Time Exceeded, and Router Advertisement and Router Solicitation. If an ICMP message cannot be delivered, no second one is generated. This is to avoid an endless flood of ICMP messages. 



When an ICMP destination-unreachable message is sent by a router, it means that the router is unable to send the package to its final destination. The router then discards the original packet. Two reasons exist for why a destination might be unreachable. Most commonly, the source host has specified a nonexistent address. Less frequently, the router does not have a route to the destination. 



Destination-unreachable messages include four basic types: network unreachable, host unreachable, protocol unreachable, and port unreachable. Network-unreachable messages usually mean that a failure has occurred in the routing or addressing of a packet. Host-unreachable messages usually indicates delivery failure, such as a wrong subnet mask. Protocol-unreachable messages generally mean that the destination does not support the upper-layer protocol specified in the packet. Port-unreachable messages imply that the TCP socket or port is not available. 



An ICMP echo-request message, which is generated by the ping command, is sent by any host to test node reachability across an internetwork. The ICMP echo-reply message indicates that the node can be successfully reached. 



An ICMP Redirect message is sent by the router to the source host to stimulate more efficient routing. The router still forwards the original packet to the destination. ICMP redirects allow host routing tables to remain small because it is necessary to know the address of only one router, even if that router does not provide the best path. Even after receiving an ICMP Redirect message, some devices might continue using the less-efficient route. 



An ICMP Time-exceeded message is sent by the router if an IP packet's Time-to-Live field (expressed in hops or seconds) reaches zero. The Time-to-Live field prevents packets from continuously circulating the internetwork if the internetwork contains a routing loop. The router then discards the original packet. 

[Guest r5]

ICMP ir tāds pats IP protokols kā TCP vai UDP, bet viņam nav nekādu portu apzīmējošu bitu kā TCP vai UDP