1925:
295:
Based on the principles of protocol layering in OSI, protocol encapsulation, not specifically GRE, breaks the layering order. It may be viewed as a separator between two different protocol stacks, one acting as a carrier for another.
1920:, Nikolaos Triantafillis; Robert J. Ordemann & Simon D. Barber, "Generic routing encapsulation tunnel keepalives", issued 2010-09-21, assigned to
1850:
2205:
1403:(PPTP) uses a variant GRE packet header structure, represented below. PPTP creates a GRE tunnel through which the PPTP GRE packets are sent.
2196:
1711:
Acknowledgment number present. Set to 1 if an acknowledgment number is supplied, indicating a PPTP GRE acknowledgment packet.
2202:
108:
1400:
125:
1767:
Present if the A bit is set; contains the sequence number of the highest GRE payload packet received by the sender.
2035:
1986:
327:
For performance reasons, GRE can also be encapsulated in UDP packets. Better throughput may be achieved by using
1235:
The original GRE RFC defined further fields in the packet header which became obsolete in the current standard:
163:
328:
220:
169:
2225:
1700:
1287:
309:
243:
97:
1856:
1684:
Sequence number bit. Set to 1 if a sequence number is supplied, indicating a PPTP GRE data packet.
287:
2230:
173:
25:
2173:
2131:
2094:
2057:
2008:
1956:
1897:
194:
104:
60:
8:
146:
1916:
696:
345:
153:
89:
35:
2212:, Entry in Cisco DocWiki (formerly known as the "Internetworking Technology Handbook")
166:
can establish ad-hoc IP over GRE tunnels which are interoperable with Cisco equipment.
2049:
2000:
1438:
1419:
1390:
bit is set; contains a list of source route entries, therefore is of variable length.
1011:
992:
734:
715:
383:
364:
305:
202:
112:
1676:
Key bit. For PPTP GRE packets, this is set to 1. (All PPTP GRE packets carry a key.)
2163:
2121:
2084:
2039:
1990:
1946:
1917:
1887:
2209:
269:
215:
2176:
2157:
2143:
2134:
2115:
2097:
2078:
2060:
2029:
2011:
1980:
1959:
1940:
1900:
1881:
1833:
1822:
1811:
1800:
1789:
1778:
73:
69:
65:
282:
2219:
2053:
2004:
256:
228:
101:
93:
45:
2156:
K. Hamzeh; G. Pall; W. Verthein; J. Taarud; W. Little; G. Zorn (July 1999).
936:
317:
1751:
Contains the Peer's Call ID for the session to which the packet belongs.
156:
interfaces to encapsulate IP data to/from Packet
Control Function (PCF).
1759:
Present if the S bit is set; contains the GRE payload sequence number.
2168:
2126:
2089:
2044:
1995:
1951:
1892:
1315:
928:
631:
188:
2155:
1255:
Routing Bit. Set to 1 if
Routing and Offset information are present.
1657:
1244:
1179:
900:
877:
587:
538:
274:
142:
to allow passing of routing information between connected networks.
1938:
1879:
2114:
D. Farinacci; T. Li; S. Hanks; D. Meyer; P. Traina (March 2000).
2113:
1330:
bit is set; contains the checksum for the GRE header and payload.
955:
bit is set; contains the checksum for the GRE header and payload.
650:
bit is set; contains the checksum for the GRE header and payload.
1978:
1692:
Strict source route bit. For PPTP GRE packets, this is set to 0.
2028:
E. Crabbe; E. Crabbet; T. Herbert (March 2017). L. Yong (ed.).
1743:
Contains the size of the payload, not including the GRE header.
1271:
Sequence number bit. Set to 1 if a sequence number is present.
606:
Sequence number bit. Set to 1 if a sequence number is present.
2027:
1921:
1350:
bit is set. An offset field indicating the offset within the
159:
136:
1727:
GRE Version number. For PPTP GRE packets, this is set to 1.
940:
932:
635:
261:
236:
207:
1851:
1378:
bit is set; contains a sequence number for the GRE packet.
686:
bit is set; contains a sequence number for the GRE packet.
1939:
S. Hanks; T. Li; D. Farinacci; P. Traina (October 1994).
1880:
S. Hanks; T. Li; D. Farinacci; P. Traina (October 1994).
1443:
1016:
739:
388:
139:
129:
971:
690:
339:
1859:- GTP-U is similar to GRE and used in cellular networks
1703:
control bits. For PPTP GRE packets, these are set to 0.
1366:
bit is set; contains an application-specific key value.
976:
The newer structure superseded the original structure:
674:
bit is set; contains an application-specific key value.
1979:
C. Pignataro; R. Bonica; S. Krishnan (October 2015).
1719:
Flag bits. For PPTP GRE packets, these are set to 0.
1982:
IPv6 Support for
Generic Routing Encapsulation (GRE)
1668:
Routing bit. For PPTP GRE packets, this is set to 0.
2217:
1942:Generic Routing Encapsulation over IPv4 networks
1794:Generic Routing Encapsulation over IPv4 networks
1346:bit is set; contains valid information, only if
699:structure is represented in the diagram below.
1735:For PPTP GRE packets, this is set to hex 880B.
1660:bit. For PPTP GRE packets, this is set to 0.
172:(DDoS) protected appliance to an unprotected
2076:
2167:
2125:
2088:
2080:Key and Sequence Number Extensions to GRE
2043:
1994:
1974:
1972:
1950:
1891:
1875:
1873:
1827:Key and Sequence Number Extensions to GRE
1394:
304:GRE packets that are encapsulated within
180:
2159:Point-to-Point Tunneling Protocol (PPTP)
1818:(proposed standard, updated by RFC 2890)
1247:bit. Set to 1 if a checksum is present.
903:bit. Set to 1 if a checksum is present.
590:bit. Set to 1 if a checksum is present.
1354:field to the active source route entry.
2218:
2149:
2107:
2070:
2021:
1969:
1932:
1870:
1263:Key bit. Set to 1 if a key is present.
598:Key bit. Set to 1 if a key is present.
972:Original GRE packet header (RFC 1701)
967:bit is set; its contents is set to 0.
691:Standard GRE packet header (RFC 2784)
340:Extended GRE packet header (RFC 2890)
299:
111:or point-to-multipoint links over an
2117:Generic Routing Encapsulation (GRE)
1883:Generic Routing Encapsulation (GRE)
1816:Generic Routing Encapsulation (GRE)
1783:Generic Routing Encapsulation (GRE)
1226:Routing (optional, variable length)
13:
1298:Reserved for future use, set to 0.
931:of the encapsulated payload. (For
634:of the encapsulated payload. (For
14:
2242:
2190:
1805:Point to Point Tunneling Protocol
1642:Acknowledgement Number (optional)
1401:Point-to-Point Tunneling Protocol
1763:Acknowledgement Number (32 bits)
344:The extended version of the GRE
334:
2199:, Subprotocol homepage at Cisco
2036:Internet Engineering Task Force
1987:Internet Engineering Task Force
118:
1910:
1:
2203:Generic Routing Encapsulation
2197:Generic Routing Encapsulation
2077:G. Dommety (September 2000).
1863:
1853:- carries L2 packets over GRE
919:GRE Version number; set to 0.
622:GRE Version number; set to 0.
329:Equal-cost multi-path routing
170:Distributed denial of service
82:Generic Routing Encapsulation
20:Generic Routing Encapsulation
1771:
1739:Key Payload Length (16 bits)
1318:of the encapsulated payload.
7:
1844:
982:Original GRE header format
705:Standard GRE header format
354:Extended GRE header format
10:
2247:
2146:.
1640:
1629:Sequence Number (optional)
1627:
1614:
1609:
1596:
1224:
1213:Sequence Number (optional)
1211:
1198:
1185:
1177:
1164:
883:
875:
862:
852:
638:, this would be hex 0800.)
572:Sequence Number (optional)
570:
557:
544:
536:
523:
308:directly, use IP protocol
2162:. Network Working Group.
2120:. Network Working Group.
2083:. Network Working Group.
1945:. Network Working Group.
1886:. Network Working Group.
1755:Sequence Number (32 bits)
1591:
1586:
1581:
1576:
1432:
1429:
1426:
1423:
1370:Sequence Number (32 bits)
1159:
1154:
1149:
1005:
1002:
999:
996:
857:
728:
725:
722:
719:
678:Sequence Number (32 bits)
518:
513:
377:
374:
371:
368:
59:
51:
41:
31:
24:
2031:GRE-in-UDP Encapsulation
1857:GPRS Tunnelling Protocol
1838:GRE-in-UDP Encapsulation
1279:Strict source route bit.
911:Reserved bits; set to 0.
662:bit is set; is set to 0.
614:Reserved bits; set to 0.
16:Cisco tunneling protocol
1731:Protocol Type (16 bits)
1409:PPTP GRE header format
1310:Protocol Type (16 bits)
923:Protocol Type (16 bits)
626:Protocol Type (16 bits)
288:Ethernet physical layer
1395:PPTP GRE packet header
943:, it would be 0x86DD.)
348:is represented below:
181:Example protocol stack
26:Communication protocol
1922:Cisco Technology Inc.
1747:Key Call ID (16 bits)
885:Reserved 1 (optional)
546:Reserved 1 (optional)
312:in the IPv4 header's
2142:Updated by RFC
959:Reserved 1 (16 bits)
907:Reserved 0 (12 bits)
654:Reserved 1 (16 bits)
135:In conjunction with
124:In conjunction with
109:point-to-point links
2226:Tunneling protocols
1840:(proposed standard)
1829:(proposed standard)
1410:
1316:ether protocol type
983:
929:ether protocol type
706:
632:ether protocol type
610:Reserved 0 (9 bits)
355:
147:mobility management
21:
2208:2018-12-29 at the
2140:Proposed Standard.
2103:Proposed Standard.
2066:Proposed Standard.
2017:Proposed Standard.
1611:Key Payload Length
1408:
1382:Routing (variable)
1322:Checksum (16 bits)
981:
947:Checksum (16 bits)
704:
642:Checksum (16 bits)
353:
300:Delivery protocols
232:(GRE-encapsulated)
100:a wide variety of
90:tunneling protocol
19:
1647:
1646:
1231:
1230:
1187:Offset (optional)
890:
889:
577:
576:
293:
292:
233:
113:Internet Protocol
79:
78:
36:Network tunneling
2238:
2184:
2180:
2171:
2169:10.17487/RFC2637
2153:
2147:
2138:
2129:
2127:10.17487/RFC2784
2111:
2105:
2101:
2092:
2090:10.17487/RFC2890
2074:
2068:
2064:
2047:
2045:10.17487/RFC8086
2025:
2019:
2015:
1998:
1996:10.17487/RFC7676
1976:
1967:
1963:
1954:
1952:10.17487/RFC1702
1936:
1930:
1929:
1928:
1924:
1914:
1908:
1904:
1895:
1893:10.17487/RFC1701
1877:
1723:Version (3 bits)
1411:
1407:
1334:Offset (16 bits)
1302:Version (3 bits)
984:
980:
935:, this would be
915:Version (3 bits)
707:
703:
618:Version (3 bits)
356:
352:
231:
195:Protocol example
185:
184:
22:
18:
2246:
2245:
2241:
2240:
2239:
2237:
2236:
2235:
2216:
2215:
2210:Wayback Machine
2193:
2188:
2187:
2154:
2150:
2112:
2108:
2075:
2071:
2026:
2022:
1977:
1970:
1937:
1933:
1926:
1915:
1911:
1878:
1871:
1866:
1847:
1807:(informational)
1796:(informational)
1785:(informational)
1774:
1397:
1374:Present if the
1362:Present if the
1326:Present if the
974:
963:Present if the
951:Present if the
695:A standard GRE
693:
682:Present if the
670:Present if the
658:Present if the
646:Present if the
342:
337:
302:
183:
121:
107:inside virtual
17:
12:
11:
5:
2244:
2234:
2233:
2228:
2214:
2213:
2200:
2192:
2191:External links
2189:
2186:
2185:
2182:Informational.
2148:
2106:
2069:
2020:
1968:
1965:Informational.
1931:
1909:
1906:Informational.
1868:
1867:
1865:
1862:
1861:
1860:
1854:
1846:
1843:
1842:
1841:
1830:
1819:
1808:
1797:
1786:
1773:
1770:
1769:
1768:
1765:
1760:
1757:
1752:
1749:
1744:
1741:
1736:
1733:
1728:
1725:
1720:
1717:
1715:Flags (4 bits)
1712:
1709:
1704:
1698:
1696:Recur (3 bits)
1693:
1690:
1685:
1682:
1677:
1674:
1669:
1666:
1661:
1655:
1649:
1648:
1645:
1644:
1639:
1636:
1632:
1631:
1626:
1623:
1619:
1618:
1613:
1608:
1605:
1601:
1600:
1595:
1590:
1585:
1580:
1575:
1570:
1565:
1560:
1555:
1550:
1547:
1543:
1542:
1539:
1536:
1533:
1530:
1527:
1524:
1521:
1518:
1515:
1512:
1509:
1506:
1503:
1500:
1497:
1494:
1491:
1488:
1485:
1482:
1479:
1476:
1473:
1470:
1467:
1464:
1461:
1458:
1455:
1452:
1449:
1446:
1441:
1435:
1434:
1431:
1428:
1425:
1422:
1417:
1396:
1393:
1392:
1391:
1384:
1379:
1372:
1367:
1360:
1355:
1336:
1331:
1324:
1319:
1314:Indicates the
1312:
1307:
1304:
1299:
1296:
1294:Flags (5 bits)
1291:
1285:
1283:Recur (3 bits)
1280:
1277:
1272:
1269:
1264:
1261:
1256:
1253:
1248:
1242:
1233:
1232:
1229:
1228:
1223:
1220:
1216:
1215:
1210:
1207:
1203:
1202:
1200:Key (optional)
1197:
1194:
1190:
1189:
1184:
1176:
1173:
1169:
1168:
1163:
1158:
1153:
1148:
1143:
1138:
1133:
1128:
1123:
1120:
1116:
1115:
1112:
1109:
1106:
1103:
1100:
1097:
1094:
1091:
1088:
1085:
1082:
1079:
1076:
1073:
1070:
1067:
1064:
1061:
1058:
1055:
1052:
1049:
1046:
1043:
1040:
1037:
1034:
1031:
1028:
1025:
1022:
1019:
1014:
1008:
1007:
1004:
1001:
998:
995:
990:
973:
970:
969:
968:
961:
956:
949:
944:
927:Indicates the
925:
920:
917:
912:
909:
904:
898:
892:
891:
888:
887:
882:
874:
871:
867:
866:
861:
856:
851:
846:
843:
839:
838:
835:
832:
829:
826:
823:
820:
817:
814:
811:
808:
805:
802:
799:
796:
793:
790:
787:
784:
781:
778:
775:
772:
769:
766:
763:
760:
757:
754:
751:
748:
745:
742:
737:
731:
730:
727:
724:
721:
718:
713:
692:
689:
688:
687:
680:
675:
668:
663:
656:
651:
644:
639:
630:Indicates the
628:
623:
620:
615:
612:
607:
604:
599:
596:
591:
585:
579:
578:
575:
574:
569:
566:
562:
561:
559:Key (optional)
556:
553:
549:
548:
543:
535:
532:
528:
527:
522:
517:
512:
507:
502:
500:
495:
492:
488:
487:
484:
481:
478:
475:
472:
469:
466:
463:
460:
457:
454:
451:
448:
445:
442:
439:
436:
433:
430:
427:
424:
421:
418:
415:
412:
409:
406:
403:
400:
397:
394:
391:
386:
380:
379:
376:
373:
370:
367:
362:
341:
338:
336:
333:
301:
298:
291:
290:
285:
278:
277:
272:
265:
264:
259:
252:
251:
246:
240:
239:
234:
224:
223:
218:
211:
210:
205:
198:
197:
192:
182:
179:
178:
177:
167:
157:
150:
143:
133:
120:
117:
77:
76:
63:
57:
56:
53:
49:
48:
43:
39:
38:
33:
29:
28:
15:
9:
6:
4:
3:
2:
2243:
2232:
2231:Cisco Systems
2229:
2227:
2224:
2223:
2221:
2211:
2207:
2204:
2201:
2198:
2195:
2194:
2183:
2178:
2175:
2170:
2165:
2161:
2160:
2152:
2145:
2141:
2136:
2133:
2128:
2123:
2119:
2118:
2110:
2104:
2099:
2096:
2091:
2086:
2082:
2081:
2073:
2067:
2062:
2059:
2055:
2051:
2046:
2041:
2037:
2033:
2032:
2024:
2018:
2013:
2010:
2006:
2002:
1997:
1992:
1988:
1984:
1983:
1975:
1973:
1966:
1961:
1958:
1953:
1948:
1944:
1943:
1935:
1923:
1919:
1913:
1907:
1902:
1899:
1894:
1889:
1885:
1884:
1876:
1874:
1869:
1858:
1855:
1852:
1849:
1848:
1839:
1835:
1831:
1828:
1824:
1820:
1817:
1813:
1809:
1806:
1802:
1798:
1795:
1791:
1787:
1784:
1780:
1776:
1775:
1766:
1764:
1761:
1758:
1756:
1753:
1750:
1748:
1745:
1742:
1740:
1737:
1734:
1732:
1729:
1726:
1724:
1721:
1718:
1716:
1713:
1710:
1708:
1705:
1702:
1699:
1697:
1694:
1691:
1689:
1686:
1683:
1681:
1678:
1675:
1673:
1670:
1667:
1665:
1662:
1659:
1656:
1654:
1651:
1650:
1643:
1637:
1634:
1633:
1630:
1624:
1621:
1620:
1617:
1612:
1606:
1603:
1602:
1599:
1598:Protocol Type
1594:
1589:
1584:
1579:
1574:
1571:
1569:
1566:
1564:
1561:
1559:
1556:
1554:
1551:
1548:
1545:
1544:
1540:
1537:
1534:
1531:
1528:
1525:
1522:
1519:
1516:
1513:
1510:
1507:
1504:
1501:
1498:
1495:
1492:
1489:
1486:
1483:
1480:
1477:
1474:
1471:
1468:
1465:
1462:
1459:
1456:
1453:
1450:
1447:
1445:
1442:
1440:
1437:
1436:
1421:
1418:
1416:
1413:
1412:
1406:
1405:
1404:
1402:
1389:
1385:
1383:
1380:
1377:
1373:
1371:
1368:
1365:
1361:
1359:
1358:Key (32 bits)
1356:
1353:
1349:
1345:
1341:
1337:
1335:
1332:
1329:
1325:
1323:
1320:
1317:
1313:
1311:
1308:
1305:
1303:
1300:
1297:
1295:
1292:
1290:control bits.
1289:
1286:
1284:
1281:
1278:
1276:
1273:
1270:
1268:
1265:
1262:
1260:
1257:
1254:
1252:
1249:
1246:
1243:
1241:
1238:
1237:
1236:
1227:
1221:
1218:
1217:
1214:
1208:
1205:
1204:
1201:
1195:
1192:
1191:
1188:
1183:
1181:
1174:
1171:
1170:
1167:
1166:Protocol Type
1162:
1157:
1152:
1147:
1144:
1142:
1139:
1137:
1134:
1132:
1129:
1127:
1124:
1121:
1118:
1117:
1113:
1110:
1107:
1104:
1101:
1098:
1095:
1092:
1089:
1086:
1083:
1080:
1077:
1074:
1071:
1068:
1065:
1062:
1059:
1056:
1053:
1050:
1047:
1044:
1041:
1038:
1035:
1032:
1029:
1026:
1023:
1020:
1018:
1015:
1013:
1010:
1009:
994:
991:
989:
986:
985:
979:
978:
977:
966:
962:
960:
957:
954:
950:
948:
945:
942:
938:
934:
930:
926:
924:
921:
918:
916:
913:
910:
908:
905:
902:
899:
897:
894:
893:
886:
881:
879:
872:
869:
868:
865:
864:Protocol Type
860:
855:
850:
847:
844:
841:
840:
836:
833:
830:
827:
824:
821:
818:
815:
812:
809:
806:
803:
800:
797:
794:
791:
788:
785:
782:
779:
776:
773:
770:
767:
764:
761:
758:
755:
752:
749:
746:
743:
741:
738:
736:
733:
732:
717:
714:
712:
709:
708:
702:
701:
700:
698:
697:packet header
685:
681:
679:
676:
673:
669:
667:
666:Key (32 bits)
664:
661:
657:
655:
652:
649:
645:
643:
640:
637:
633:
629:
627:
624:
621:
619:
616:
613:
611:
608:
605:
603:
600:
597:
595:
592:
589:
586:
584:
581:
580:
573:
567:
564:
563:
560:
554:
551:
550:
547:
542:
540:
533:
530:
529:
526:
525:Protocol Type
521:
516:
511:
508:
506:
503:
501:
499:
496:
493:
490:
489:
485:
482:
479:
476:
473:
470:
467:
464:
461:
458:
455:
452:
449:
446:
443:
440:
437:
434:
431:
428:
425:
422:
419:
416:
413:
410:
407:
404:
401:
398:
395:
392:
390:
387:
385:
382:
381:
366:
363:
361:
358:
357:
351:
350:
349:
347:
346:packet header
335:Packet header
332:
330:
325:
323:
319:
316:field or the
315:
311:
307:
297:
289:
286:
284:
280:
279:
276:
273:
271:
267:
266:
263:
260:
258:
254:
253:
250:
247:
245:
244:Encapsulation
242:
241:
238:
235:
230:
226:
225:
222:
219:
217:
213:
212:
209:
206:
204:
200:
199:
196:
193:
190:
187:
186:
175:
171:
168:
165:
161:
158:
155:
151:
148:
144:
141:
138:
134:
131:
127:
123:
122:
116:
114:
110:
106:
103:
102:network layer
99:
95:
94:Cisco Systems
92:developed by
91:
87:
83:
75:
71:
67:
64:
62:
58:
54:
50:
47:
46:Cisco Systems
44:
40:
37:
34:
30:
27:
23:
2181:
2158:
2151:
2139:
2116:
2109:
2102:
2079:
2072:
2065:
2030:
2023:
2016:
1981:
1964:
1941:
1934:
1918:US 7801021B1
1912:
1905:
1882:
1837:
1826:
1815:
1804:
1793:
1782:
1762:
1754:
1746:
1738:
1730:
1722:
1714:
1706:
1695:
1687:
1679:
1671:
1663:
1652:
1641:
1628:
1615:
1610:
1597:
1592:
1587:
1582:
1577:
1572:
1567:
1562:
1557:
1552:
1414:
1398:
1387:
1381:
1375:
1369:
1363:
1357:
1351:
1347:
1343:
1339:
1333:
1327:
1321:
1309:
1301:
1293:
1282:
1274:
1266:
1258:
1250:
1239:
1234:
1225:
1212:
1199:
1186:
1178:
1165:
1160:
1155:
1150:
1145:
1140:
1135:
1130:
1125:
987:
975:
964:
958:
952:
946:
939:0x0800; for
922:
914:
906:
895:
884:
876:
863:
858:
853:
848:
710:
694:
683:
677:
671:
665:
659:
653:
647:
641:
625:
617:
609:
601:
593:
582:
571:
558:
545:
537:
524:
519:
514:
509:
504:
497:
359:
343:
326:
321:
313:
303:
294:
248:
119:Example uses
85:
81:
80:
52:Introduction
42:Developer(s)
1616:Key Call ID
1386:Present if
1338:Present if
937:hexadecimal
322:Next Header
318:IPv6 header
203:Application
98:encapsulate
2220:Categories
1864:References
1182:(optional)
880:(optional)
854:Reserved 0
541:(optional)
515:Reserved 0
149:protocols.
128:to create
2054:2070-1721
2005:2070-1721
1832:RFC
1821:RFC
1810:RFC
1799:RFC
1788:RFC
1777:RFC
1772:Standards
1707:A (1 bit)
1701:Recursion
1688:s (1 bit)
1680:S (1 bit)
1672:K (1 bit)
1664:R (1 bit)
1653:C (1 bit)
1306:Set to 0.
1288:Recursion
1275:s (1 bit)
1267:S (1 bit)
1259:K (1 bit)
1251:R (1 bit)
1240:C (1 bit)
896:C (1 bit)
602:S (1 bit)
594:K (1 bit)
583:C (1 bit)
270:Data link
216:Transport
189:OSI model
115:network.
105:protocols
96:that can
2206:Archived
2038:(IETF).
1989:(IETF).
1845:See also
1658:Checksum
1245:Checksum
1180:Checksum
901:Checksum
878:Checksum
588:Checksum
539:Checksum
314:Protocol
283:Physical
275:Ethernet
174:endpoint
1593:Version
1415:Offsets
1352:Routing
1342:bit or
1161:Version
988:Offsets
859:Version
711:Offsets
520:Version
360:Offsets
324:field.
310:type 47
257:Network
229:Network
88:) is a
32:Purpose
2052:
2003:
1927:
191:layer
154:A8/A10
61:RFC(s)
1588:Flags
1578:Recur
1439:Octet
1420:Octet
1156:Flags
1151:Recur
1012:Octet
993:Octet
735:Octet
716:Octet
384:Octet
365:Octet
160:Linux
137:IPsec
2177:2637
2144:2890
2135:2784
2098:2890
2061:8086
2050:ISSN
2012:7676
2001:ISSN
1960:1702
1901:1701
1834:8086
1823:2890
1812:2784
1801:2637
1790:1702
1779:1701
1399:The
1222:128
941:IPv6
933:IPv4
636:IPv4
262:IPv6
237:IPv4
208:HTTP
162:and
140:VPNs
130:VPNs
126:PPTP
74:2784
70:1702
66:1701
55:1994
2174:RFC
2164:doi
2132:RFC
2122:doi
2095:RFC
2085:doi
2058:RFC
2040:doi
2009:RFC
1991:doi
1957:RFC
1947:doi
1898:RFC
1888:doi
1638:96
1635:12
1625:64
1607:32
1541:31
1538:30
1535:29
1532:28
1529:27
1526:26
1523:25
1520:24
1517:23
1514:22
1511:21
1508:20
1505:19
1502:18
1499:17
1496:16
1493:15
1490:14
1487:13
1484:12
1481:11
1478:10
1444:Bit
1219:16
1209:96
1206:12
1196:64
1175:32
1114:31
1111:30
1108:29
1105:28
1102:27
1099:26
1096:25
1093:24
1090:23
1087:22
1084:21
1081:20
1078:19
1075:18
1072:17
1069:16
1066:15
1063:14
1060:13
1057:12
1054:11
1051:10
1017:Bit
873:32
837:31
834:30
831:29
828:28
825:27
822:26
819:25
816:24
813:23
810:22
807:21
804:20
801:19
798:18
795:17
792:16
789:15
786:14
783:13
780:12
777:11
774:10
740:Bit
568:96
565:12
555:64
534:32
486:31
483:30
480:29
477:28
474:27
471:26
468:25
465:24
462:23
459:22
456:21
453:20
450:19
447:18
444:17
441:16
438:15
435:14
432:13
429:12
426:11
423:10
389:Bit
320:'s
281:1.
268:2.
255:3.
249:GRE
227:3.
221:TCP
214:4.
201:7.
164:BSD
152:In
145:In
86:GRE
2222::
2172:.
2130:.
2093:.
2056:.
2048:.
2034:.
2007:.
1999:.
1985:.
1971:^
1955:.
1896:.
1872:^
1836::
1825::
1814::
1803::
1792::
1781::
1622:8
1604:4
1549:0
1546:0
1475:9
1472:8
1469:7
1466:6
1463:5
1460:4
1457:3
1454:2
1451:1
1448:0
1433:3
1430:2
1427:1
1424:0
1193:8
1172:4
1122:0
1119:0
1048:9
1045:8
1042:7
1039:6
1036:5
1033:4
1030:3
1027:2
1024:1
1021:0
1006:3
1003:2
1000:1
997:0
870:4
845:0
842:0
771:9
768:8
765:7
762:6
759:5
756:4
753:3
750:2
747:1
744:0
729:3
726:2
723:1
720:0
552:8
531:4
494:0
491:0
420:9
417:8
414:7
411:6
408:5
405:4
402:3
399:2
396:1
393:0
378:3
375:2
372:1
369:0
331:.
306:IP
72:,
68:,
2179:.
2166::
2137:.
2124::
2100:.
2087::
2063:.
2042::
2014:.
1993::
1962:.
1949::
1903:.
1890::
1583:A
1573:s
1568:S
1563:K
1558:R
1553:C
1388:R
1376:S
1364:K
1348:R
1344:C
1340:R
1328:C
1146:s
1141:S
1136:K
1131:R
1126:C
965:C
953:C
849:C
684:S
672:K
660:C
648:C
510:S
505:K
498:C
176:.
132:.
84:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.