ICMP-
ICMP-. ( * , - ):
ICMP- | ||
- (ping-) | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* (quench) | ||
( ) | ||
() | ||
(tos) | ||
(ping-). | ||
(ttl=0): | ||
* | ||
* ( ). | ||
* | ||
* ip- | ||
* | ||
- | ||
() | ||
() | ||
" " (quench, ICMP=4) . , - " " , . , , . , .
ICMP
. 4.4.4.2. - ICMP
( ) ( 1 ) , . , (8) (0). 16- 1 ICMP-, . , . ping - . , IP-, . -, , , , (RTT - round trip time). IP-.
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ICMP , PING . . |
, . ICMP- , . , . , , .
ICMP-, , . . .
, " " (destination unreachable). ( . 4.4.4.3).
. 4.4.4.3. ICMP- " "
, . 4.4.4.1. MTU .
- 64- , , . ICMP- , DF=1 (" "), . 4.
, 4 .
, ICMP, , , ( ). NTP (network time protocol) RFC-1119.
, (quench-), , quench-. :
. 4.4.4.4. icmp-
Internet , . , , ICMP- . 4.4.4.5.
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. 4.4.4.5. ICMP-
Internet- , , , . internet- 64 , . , (. . 4.4.4.1).
. . M1. , , , M2. , M1 M2 , M1. , M2 -. M1 ICMP- - , .
, , , . . . , ( 450-600 .) , . RFC-1256 ICMP- (. . 4.4.4.6).
. 4.4.4.6. ICMP-
. 32- , . () . 30 . . . 0. (8 , . 4.4.4.7).
. 4.4.4.7
(hop) , . (TTL). TTL " ", (. 4.4.4.8):
. 4.4.4.8. " (ttl) "
- (. . 4.4.4.1).
- , (, ), " ". . (. 4.4.4.9):
. 4.4.4.9. " "
, . =1 , (, ), =1 .
. (, ), . , (. 4.4.4.10):
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. 4.4.4.10. ICMP-
=13 , , =14 - , . . . , - . ping traceroute. , . , traceroute cernvm.cern.ch, SUN (), ( IP- , RTT ):
traceroute to crnvma.cern.ch | (128.141.2.4) 30 hops max, 40 byte packets | |
itep-fddi-bbone | (193.124.224.50) 3 ms 2 ms 3 ms | |
msu-tower.moscow.ru.radio-msu.net | (193.124.137.13) 3 ms 3 ms 3 ms | |
npi-msu.moscow.ru.radio-msu.net | (193.124.137.9) 27 ms 3 ms 9 ms | |
desy.hamburg.de.radio-msu.net | (193.124.137.6) 556 ms 535 ms 535 ms | |
* 188.1.133.56 | (188.1.133.56) 637ms 670ms | |
duesseldorf2.empb.net | (193.172.4.12) 740ms(ttl=59!) 839ms(ttl=59!) 2066ms(ttl=59!) | |
bern3.empb.net | (193.172.4.30) 2135ms (ttl=58!) 1644ms (ttl=58!) 1409ms (ttl=58!) | |
cernh3.euro-hep.net | (193.172.24.10) 1808ms 1508ms 1830ms | |
cgate1.cern.ch | (192.65.185.1) 1116ms 1270ms 1278ms | |
crnvma.cern.ch | (128.141.2.4) 1132ms 1362ms 1524ms |
, ---CERN. , - 500 . - (X.25, 256/) . IP X.25 . . ping . , , . , ICMP, , "" .
. , IP- . " " , . , , . - (. 4.4.4.11).
. 4.4.4.11. ()
, =17 - , =18 - . , , , 32- .
.