Year 1115 was a common year starting on Friday of the Julian calendar. September 14 – Battle of Sarmin: The Crusaders, under Prince Roger of Salerno and rout the Seljuk Turkish army, led by Emir Bursuq ibn Bursuq, at Sarmin. Bursuq avoids capture, escapes with a few hundred horseman. Roger reoccupies the fortress of Kafartab, consolidates his territory around Antioch; the Crusader castle of Montréal is commissioned by King Baldwin I of Jerusalem, during an expedition against the Seljuk Turks. February 11 – Battle of Welfesholz: Duke Lothair of Supplinburg joins the rebellious Saxon forces, defeats the German Imperial Army of Emperor Henry V at Welfesholz, in Saxony-Anhalt. July 24 – Matilda, margravine of Tuscany, dies at Bondeno. During her reign she waged an intermittent war with the late Emperor Henry IV, over the inheritance rights of her fiefs in Lombardy and Tuscany; the Jin Dynasty is created by the Jurchen tribal chieftain Taizu. He establishes a dual-administration system: a Chinese-style bureaucracy to rule over northern and northeast China.

The 19-year-old Minamoto no Tameyoshi, Japanese nobleman and samurai, gains recognition by suppressing a riot against Emperor Toba at a monastery near Kyoto. The Mixtec ruler Eight Deer Jaguar Claw is defeated in battle and sacrificed by a coalition of city-states, led by his brother-in law 4 Wind, at Tilantongo in the Mixteca Alta region. Arnulf of Chocques is accused of sexual relations with a Muslim woman, he is removed from his position as patriarch of Jerusalem. Peter Abelard, French scholastic philosopher, becomes master of the cathedral school of Notre-Dame and meets Héloïse d'Argenteuil. Clairvaux Abbey is founded by Bernard, French abbot and a major leader in the reform of Benedictine monasticism, in France. Hugh of Saint Victor, French theologian and writer, joins the Victorines in Paris. April 18 – Gertrude, German duchess and regent September 18 – Wu, Chinese empress consort Aubrey de Vere, 1st Earl of Oxford Berenguer Raymond, count of Provence Erling Skakke, Norwegian nobleman Eustathius of Thessalonica, Byzantine archbishop Euthymios Malakes, Byzantine bishop Fulk I FitzWarin, English nobleman Gilbert FitzRichard de Clare, 1st Earl of Hertford Hugo Etherianus, Italian cardinal and adviser Li Tao, Chinese historian and writer Magnus IV, king of Norway Pedro Fernández de Castro, Spanish nobleman Peter Cellensis, French abbot and bishop Roger de Pont L'Évêque, Norman archbishop Welf VI, margrave of Tuscany Wichmann von Seeburg, German archbishop William V, marquess of Montferrat April 16 – Magnus Erlendsson, Earl of Orkney July 8 – Peter the Hermit, French religious leader July 24 – Matilda, margravine of Tuscany December 22 – Olav Magnusson, king of Norway December 23 – Ivo of Chartres, French bishop December 30 – Theodoric II, duke of Lorraine Abu al-Mu'in al-Nasafi, Arab theologian Adela of Flanders, queen of Denmark Artau II, count of Pallars Sobirà Eight Deer Jaguar Claw, Mixtec ruler Gerberga, countess of Provence Godfrey of Amiens, French bishop Leo Marsicanus, Italian cardinal Mazdali ibn Tilankan, Almoravid governor Odo II, count of Champagne Reynelm, bishop of Hereford Shin Arahan, Burmese religious adviser Tanchelm of Antwerp, Flemish priest Turgot of Durham, Scottish bishop

Individual rank insignia to the ground forces and naval forces were established by orders 2590 and 2591, effective from September 22, 1935. This was directed to supreme commanders, commanding officers, personnel in charge to exert command and control in the Workers' and Peasants' Red Army, published by order number 176 of the USSR People's Commissariat of Defense, dated from December 03, 1935. According to these new orders, new insignia of command personnel should indicate: Branch of service, or special troops Qualification, professional responsibility, specific knowledge Rank insignia, operational/ tactical responsibility, e.g. level of military command, unit, or sub-unit. The top military rank of Marshal of the Soviet Union was created by order of the USSR Central Executive Committee and the “Council of People's Commissars” from September 22, 1935 onward, before the new ranks were issued; the military ranks created as a result of the joint decision of the “USSR Central Executive Committee” and the “Council of People's Commissars” from November 21, 1935 are contained in the table below.

These replaced the ranks used from 1924. The same orders mentioned above provided for separate ranks for the Political commissars and military specialists, as in the table below. More regulations were established following general instructions of the Red Army. According to paragraph 10 of this instruction, the following subdivision of personnel was made: Leading staff: Military officers and heads of departments, military administration and commissariat, medical service, veterinarian service, military legal service Commanding staff: Personnel with the ranks commander in chief and commander Junior commanding staff Enlisted men/ratingsParagraph 14 of this instruction contained the individual ranks and rank designations according to the order of September 22, 1935, thus sanctioned the additional established OF-1c ranks, taking effect on August 5, 1937. By decision of the extraordinary session of the Supreme Soviet of the USSR the law on universal compulsory service took effect, the new OF4-ranks of Podpolkovnik and Battalion commissar were introduced as a result of the amendments to the rank regulations of 1935.

An equivalent OF4-rank for the Soviet navy was not established, however. In addition to individual ranks the establishment of defined rank insignia was made in December 1935 as well. From this time military staff, including political commissars, military administration, medical service, veterinarian service, military legal service of the Red Army wore rank insignia as follows: Rank insignia chevron: on both sleeves Rank insignia big: on both collar-edges of the uniform coat Rank insignia small: on both collar-edges of the battle jacket However, naval military staff wore sleeve insignia on both sleeves of the uniform. Commander in chief, higher commanding officers and top appointments OF10 to OF6Rank insignia, big: on a rhombic padding, gold coloured border, one to four rhombic red enameled badges, gold coloured Soviet star small/ big Rank insignia, small: on rectangle padding, gold coloured border, one to four rhombic red enameled badges Sleeve insignia: one to four gold colored chevrons, Soviet star small/ big, one red coloured extra chevron OF10Commanding officers and unit leaders OF5, OF3 and OF2Rank insignia big: on rhombic padding, gold coloured border, one to three red enameled rectangle badges Rank insignia small: on rectangle padding, gold coloured border, one to four red enameled rectangle badgesSubunit leader OF1Rank insignia big: on rhombic padding, gold coloured border, one to four red enameled square badges Rank insignia small: on rectangle padding, gold coloured border, one to four red enameled square badgesSub-subunit leader and enlisted men OR8 to OR1Sub-subunit leader Rank insignia big: on rhombic padding, gold coloured border, one to three red enameled triangular badges Rank insignia small: on rectangle padding, gold coloured border, one to four red enameled triangular badges Enlisted men: simple rank insignia big / simple rank insignia small The following ranks and insignia were used by the Soviet Navy from 1935 to 1940.

History of Russian military ranks Ranks and rank insignia of the Russian armed forces until 1917 Ranks and insignia of the Red Army and Navy 1918–1935, and... 1940–1943 Ranks and rank insignia of the Soviet Armed Forces 1943–1955, and... 1955–1991 Ranks and rank insignia of the Russian Federation´s armed forces 1994–2010

Path MTU Discovery is a standardized technique in computer networking for determining the maximum transmission unit size on the network path between two Internet Protocol hosts with the goal of avoiding IP fragmentation. PMTUD was intended for routers in Internet Protocol Version 4. However, all modern operating systems use it on endpoints. In IPv6, this function has been explicitly delegated to the end points of a communications session. PMTUD is standardized for IPv4 in RFC 1191 and for IPv6 in RFC 8201. RFC 4821 describes an extension to the techniques that works without support from Internet Control Message Protocol. For IPv4 packets, Path MTU Discovery works by setting the Don't Fragment flag bit in the IP headers of outgoing packets. Any device along the path whose MTU is smaller than the packet will drop it, send back an Internet Control Message Protocol Fragmentation Needed message containing its MTU, allowing the source host to reduce its Path MTU appropriately; the process is repeated until the MTU is small enough to traverse the entire path without fragmentation.

IPv6 routers do not support fragmentation and don't support the Don't Fragment option. For IPv6, Path MTU Discovery works by assuming the path MTU is the same as the MTU on the link layer interface where the traffic originates. Similar to IPv4, any device along the path whose MTU is smaller than the packet will drop the packet and send back an ICMPv6 Packet Too Big message containing its MTU, allowing the source host to reduce its Path MTU appropriately; the process is repeated until the MTU is small enough to traverse the entire path without fragmentation. If the Path MTU changes after the connection is set up and is lower than the determined Path MTU, the first large packet will cause an ICMP error and the new, lower Path MTU will be found. Conversely, if PMTUD finds that the path allows a larger MTU than is possible on the lower link, the OS will periodically reprobe to see if the path has changed and now allows larger packets. On both Linux and Windows this timer is set by default to ten minutes.

Many network security devices block all ICMP messages for perceived security benefits, including the errors that are necessary for the proper operation of PMTUD. This can result in connections that complete the TCP three-way handshake but hang when data is transferred; this state is referred to as a black hole connection. Some implementations of PMTUD attempt to prevent this problem by inferring that large payload packets have been dropped due to MTU rather than because of link congestion. However, in order for the Transmission Control Protocol to operate most efficiently, ICMP Unreachable messages should be permitted. A robust method for PMTUD that relies on TCP or another protocol to probe the path with progressively larger packets has been standardized in RFC 4821. A workaround used by some routers is to change the maximum segment size of all TCP connections passing through links with MTU lower than the Ethernet default of 1500; this is known as MSS clamping