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Diffstat (limited to 'docs/ref/tran/udp.md')
| -rw-r--r-- | docs/ref/tran/udp.md | 41 |
1 files changed, 22 insertions, 19 deletions
diff --git a/docs/ref/tran/udp.md b/docs/ref/tran/udp.md index 7093ea3e..59dfd485 100644 --- a/docs/ref/tran/udp.md +++ b/docs/ref/tran/udp.md @@ -16,7 +16,7 @@ that all messages sent will arrive. > [!NOTE] > This transport is _experimental_. -## URI Format +## URL Format This transport uses URIs using the scheme {{i:`udp://`}}, followed by an IP address or hostname, followed by a colon and finally a @@ -56,20 +56,23 @@ and could be used to listen to port 9999 on the host: ## Socket Address -When using an [`nng_sockaddr`][nng_sockaddr] structure, +When using an [`nng_sockaddr`] structure, the actual structure is either of type -[`nng_sockaddr_in`][nng_sockaddr_in] (for IPv4) or -[`nng_sockaddr_in6`][nng_sockaddr_in6] (for IPv6). +[`nng_sockaddr_in`] (for IPv4) or +[`nng_sockaddr_in6`] (for IPv6). ## Transport Options The following transport options are supported by this transport, where supported by the underlying platform. -- [`NNG_OPT_LOCADDR`][NNG_OPT_LOCADDR] -- [`NNG_OPT_REMADDR`][NNG_OPT_REMADDR] - -TODO: Document other options. +| Option | Type | Description | +| ------------------------------------------------------------- | ---------------- | -------------------------------------------------------------------------------------------------------------------------------- | +| [`NNG_OPT_LOCADDR`] | [`nng_sockaddr`] | The locally bound address, will be either [`nng_sockaddr_in`] or [`nng_sockaddr_in6`]. | +| [`NNG_OPT_REMADDR`] | [`nng_sockaddr`] | The remote peer address, will be either [`nng_sockaddr_in`] or [`nng_sockaddr_in6`]. Only valid for [pipe] and [dialer] objects. | +| [`NNG_OPT_RECVMAXSZ`] | `size_t` | Maximum size of incoming messages, will be limited to at most 65000. | +| `NNG_OPT_UDP_COPY_MAX`<a name="NNG_OPT_UDP_COPY_MAX"></a> | `size_t` | Threshold above which received messages are "loaned" up, rather than a new message being allocated and copied into. | +| `NNG_OPT_UDP_BOUND_PORT`<a name="NNG_OPT_UDP_BOUND_PORT"></a> | `int` | The locally bound UDP port number (1-65535), read-only for [listener] objects only. | ## Maximum Message Size @@ -82,15 +85,20 @@ very much smaller messages, ideally those that will fit within a single network packet without requiring fragmentation and reassembly. For Ethernet without jumbo frames, this typically means an {{i:MTU}} of a little -less than 1500 bytes. (Specifically, 1452, which allows 28 bytes for IP and UDP, -and 20 bytes for the this transport). -Other link layers may have different MTUs. +less than 1500 bytes. (Specifically, 1452, which allows 28 bytes for IPv4 and UDP, +and 20 bytes for the this transport. Reduce by an additional 20 bytes for IPv6.) + +Other link layers may have different MTUs, however IPv6 requires a minimum MTU of 1280, +which after deducting 48 bytes for IPv6 and UDP headers, and 20 bytes for our transport +header, leaves 1212 bytes for user data. If additional allowances are made for SP protocol +headers with a default TTL of 8 (resulting in 72 additional bytes for route information), +the final user accessible payload will be 1140 bytes. Thus this can be likely be viewed +as a safe maxmimum to employ for SP payload data across all transports. The maximum message size is negotiated as part of establishing a peering relationship, and oversize messages will be dropped by the sender before going to the network. -The maximum message size to receive can be configured with the -[`NNG_OPT_RECVMAXSZ`][NNG_OPT_RECVMAXSZ] option. +The maximum message size to receive can be configured with the [`NNG_OPT_RECVMAXSZ`] option. ## Keep Alive @@ -101,9 +109,4 @@ keep-alive mechanism is implemented. TODO: Document the tunables for this. -[nng_sockaddr]: [TODO.md] -[nng_sockaddr_in]: [TODO.md] -[nng_sockaddr_in6]: [TODO.md] -[NNG_OPT_LOCADDR]: [TODO.md] -[NNG_OPT_REMADDR]: [TODO.md] -[NNG_OPT_RECVMAXSZ]: [TODO.md] +{{#include ../xref.md}} |