First pass of configurable MTU and max MTU increase.

This commit is contained in:
Adam Ierymenko 2017-05-04 17:12:02 -07:00
parent 6ef247fb93
commit 107e3e4106
6 changed files with 22 additions and 29 deletions

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@ -61,28 +61,8 @@ extern "C" {
/**
* Maximum MTU for ZeroTier virtual networks
*
* This is pretty much an unchangeable global constant. To make it change
* across nodes would require logic to send ICMP packet too big messages,
* which would complicate things. 1500 has been good enough on most LANs
* for ages, so a larger MTU should be fine for the forseeable future. This
* typically results in two UDP packets per single large frame. Experimental
* results seem to show that this is good. Larger MTUs resulting in more
* fragments seemed too brittle on slow/crummy links for no benefit.
*
* If this does change, also change it in tap.h in the tuntaposx code under
* mac-tap.
*
* Overhead for a normal frame split into two packets:
*
* 1414 = 1444 (typical UDP MTU) - 28 (packet header) - 2 (ethertype)
* 1428 = 1444 (typical UDP MTU) - 16 (fragment header)
* SUM: 2842
*
* We use 2800, which leaves some room for other payload in other types of
* messages such as multicast propagation or future support for bridging.
*/
#define ZT_MAX_MTU 2800
#define ZT_MAX_MTU 10000
/**
* Maximum length of network short name

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@ -159,15 +159,12 @@
/**
* Default MTU used for Ethernet tap device
*/
#define ZT_IF_MTU ZT_MAX_MTU
#define ZT_DEFAULT_MTU 2800
/**
* Maximum number of packet fragments we'll support
*
* The actual spec allows 16, but this is the most we'll support right
* now. Packets with more than this many fragments are dropped.
* Maximum number of packet fragments we'll support (protocol max: 16)
*/
#define ZT_MAX_PACKET_FRAGMENTS 4
#define ZT_MAX_PACKET_FRAGMENTS 7
/**
* Size of RX queue

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@ -1125,7 +1125,7 @@ bool IncomingPacket::_doMULTICAST_FRAME(const RuntimeEnvironment *RR,void *tPtr,
//TRACE("<<MC FRAME %.16llx/%s from %s@%s flags %.2x length %u",nwid,to.toString().c_str(),from.toString().c_str(),peer->address().toString().c_str(),flags,frameLen);
if ((frameLen > 0)&&(frameLen <= ZT_IF_MTU)) {
if ((frameLen > 0)&&(frameLen <= ZT_MAX_MTU)) {
if (!to.mac().isMulticast()) {
TRACE("dropped MULTICAST_FRAME from %s@%s(%s) to %s: destination is unicast, must use FRAME or EXT_FRAME",from.toString().c_str(),peer->address().toString().c_str(),_path->address().toString().c_str(),to.toString().c_str());
peer->received(tPtr,_path,hops(),packetId(),Packet::VERB_MULTICAST_FRAME,0,Packet::VERB_NOP,true); // trustEstablished because COM is okay

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@ -1225,6 +1225,8 @@ void Network::requestConfiguration(void *tPtr)
nconf->revision = 1;
nconf->issuedTo = RR->identity.address();
nconf->flags = ZT_NETWORKCONFIG_FLAG_ENABLE_IPV6_NDP_EMULATION;
nconf->mtu = ZT_DEFAULT_MTU;
nconf->multicastLimit = 0;
nconf->staticIpCount = 1;
nconf->ruleCount = 14;
nconf->staticIps[0] = InetAddress::makeIpv66plane(_id,RR->identity.address().toInt());
@ -1495,7 +1497,7 @@ void Network::_externalConfig(ZT_VirtualNetworkConfig *ec) const
else ec->name[0] = (char)0;
ec->status = _status();
ec->type = (_config) ? (_config.isPrivate() ? ZT_NETWORK_TYPE_PRIVATE : ZT_NETWORK_TYPE_PUBLIC) : ZT_NETWORK_TYPE_PRIVATE;
ec->mtu = ZT_IF_MTU;
ec->mtu = (_config) ? _config.mtu : ZT_DEFAULT_MTU;
ec->physicalMtu = ZT_UDP_DEFAULT_PAYLOAD_MTU - (ZT_PACKET_IDX_PAYLOAD + 16);
ec->dhcp = 0;
std::vector<Address> ab(_config.activeBridges());

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@ -51,6 +51,7 @@ bool NetworkConfig::toDictionary(Dictionary<ZT_NETWORKCONFIG_DICT_CAPACITY> &d,b
if (!d.add(ZT_NETWORKCONFIG_DICT_KEY_MULTICAST_LIMIT,(uint64_t)this->multicastLimit)) return false;
if (!d.add(ZT_NETWORKCONFIG_DICT_KEY_TYPE,(uint64_t)this->type)) return false;
if (!d.add(ZT_NETWORKCONFIG_DICT_KEY_NAME,this->name)) return false;
if (!d.add(ZT_NETWORKCONFIG_DICT_KEY_MTU,(uint64_t)this->mtu)) return false;
#ifdef ZT_SUPPORT_OLD_STYLE_NETCONF
if (includeLegacy) {
@ -217,6 +218,12 @@ bool NetworkConfig::fromDictionary(const Dictionary<ZT_NETWORKCONFIG_DICT_CAPACI
this->multicastLimit = (unsigned int)d.getUI(ZT_NETWORKCONFIG_DICT_KEY_MULTICAST_LIMIT,0);
d.get(ZT_NETWORKCONFIG_DICT_KEY_NAME,this->name,sizeof(this->name));
this->mtu = (unsigned int)d.getUI(ZT_NETWORKCONFIG_DICT_KEY_MTU,ZT_DEFAULT_MTU);
if (this->mtu < 1280)
this->mtu = 1280; // minimum MTU allowed by IPv6 standard and others
else if (this->mtu > ZT_MAX_MTU)
this->mtu = ZT_MAX_MTU;
if (d.getUI(ZT_NETWORKCONFIG_DICT_KEY_VERSION,0) < 6) {
#ifdef ZT_SUPPORT_OLD_STYLE_NETCONF
char tmp2[1024];

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@ -167,6 +167,8 @@ namespace ZeroTier {
#define ZT_NETWORKCONFIG_DICT_KEY_TYPE "t"
// text
#define ZT_NETWORKCONFIG_DICT_KEY_NAME "n"
// network MTU
#define ZT_NETWORKCONFIG_DICT_KEY_MTU "mtu"
// credential time max delta in ms
#define ZT_NETWORKCONFIG_DICT_KEY_CREDENTIAL_TIME_MAX_DELTA "ctmd"
// binary serialized certificate of membership
@ -465,6 +467,11 @@ public:
*/
uint64_t flags;
/**
* Network MTU
*/
unsigned int mtu;
/**
* Maximum number of recipients per multicast (not including active bridges)
*/