diff options
Diffstat (limited to 'Documentation/networking')
| -rw-r--r-- | Documentation/networking/dccp.txt | 29 | ||||
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 27 | ||||
| -rw-r--r-- | Documentation/networking/phonet.txt | 16 | ||||
| -rw-r--r-- | Documentation/networking/timestamping.txt | 22 |
4 files changed, 74 insertions, 20 deletions
diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt index a62fdf7a6bff..271d524a4c8d 100644 --- a/Documentation/networking/dccp.txt +++ b/Documentation/networking/dccp.txt @@ -1,18 +1,20 @@ DCCP protocol -============ +============= Contents ======== - - Introduction - Missing features - Socket options +- Sysctl variables +- IOCTLs +- Other tunables - Notes + Introduction ============ - Datagram Congestion Control Protocol (DCCP) is an unreliable, connection oriented protocol designed to solve issues present in UDP and TCP, particularly for real-time and multimedia (streaming) traffic. @@ -29,9 +31,9 @@ It has a base protocol and pluggable congestion control IDs (CCIDs). DCCP is a Proposed Standard (RFC 2026), and the homepage for DCCP as a protocol is at http://www.ietf.org/html.charters/dccp-charter.html + Missing features ================ - The Linux DCCP implementation does not currently support all the features that are specified in RFCs 4340...42. @@ -45,7 +47,6 @@ http://linux-net.osdl.org/index.php/DCCP_Testing#Experimental_DCCP_source_tree Socket options ============== - DCCP_SOCKOPT_SERVICE sets the service. The specification mandates use of service codes (RFC 4340, sec. 8.1.2); if this socket option is not set, the socket will fall back to 0 (which means that no meaningful service code @@ -112,6 +113,7 @@ DCCP_SOCKOPT_CCID_TX_INFO On unidirectional connections it is useful to close the unused half-connection via shutdown (SHUT_WR or SHUT_RD): this will reduce per-packet processing costs. + Sysctl variables ================ Several DCCP default parameters can be managed by the following sysctls @@ -155,15 +157,30 @@ sync_ratelimit = 125 ms sequence-invalid packets on the same socket (RFC 4340, 7.5.4). The unit of this parameter is milliseconds; a value of 0 disables rate-limiting. + IOCTLS ====== FIONREAD Works as in udp(7): returns in the `int' argument pointer the size of the next pending datagram in bytes, or 0 when no datagram is pending. + +Other tunables +============== +Per-route rto_min support + CCID-2 supports the RTAX_RTO_MIN per-route setting for the minimum value + of the RTO timer. This setting can be modified via the 'rto_min' option + of iproute2; for example: + > ip route change 10.0.0.0/24 rto_min 250j dev wlan0 + > ip route add 10.0.0.254/32 rto_min 800j dev wlan0 + > ip route show dev wlan0 + CCID-3 also supports the rto_min setting: it is used to define the lower + bound for the expiry of the nofeedback timer. This can be useful on LANs + with very low RTTs (e.g., loopback, Gbit ethernet). + + Notes ===== - DCCP does not travel through NAT successfully at present on many boxes. This is because the checksum covers the pseudo-header as per TCP and UDP. Linux NAT support for DCCP has been added. diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index f350c69b2bb4..c7165f4cb792 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -1014,6 +1014,12 @@ conf/interface/*: accept_ra - BOOLEAN Accept Router Advertisements; autoconfigure using them. + Possible values are: + 0 Do not accept Router Advertisements. + 1 Accept Router Advertisements if forwarding is disabled. + 2 Overrule forwarding behaviour. Accept Router Advertisements + even if forwarding is enabled. + Functional default: enabled if local forwarding is disabled. disabled if local forwarding is enabled. @@ -1075,7 +1081,12 @@ forwarding - BOOLEAN Note: It is recommended to have the same setting on all interfaces; mixed router/host scenarios are rather uncommon. - FALSE: + Possible values are: + 0 Forwarding disabled + 1 Forwarding enabled + 2 Forwarding enabled (Hybrid Mode) + + FALSE (0): By default, Host behaviour is assumed. This means: @@ -1085,18 +1096,24 @@ forwarding - BOOLEAN Advertisements (and do autoconfiguration). 4. If accept_redirects is TRUE (default), accept Redirects. - TRUE: + TRUE (1): If local forwarding is enabled, Router behaviour is assumed. This means exactly the reverse from the above: 1. IsRouter flag is set in Neighbour Advertisements. 2. Router Solicitations are not sent. - 3. Router Advertisements are ignored. + 3. Router Advertisements are ignored unless accept_ra is 2. 4. Redirects are ignored. - Default: FALSE if global forwarding is disabled (default), - otherwise TRUE. + TRUE (2): + + Hybrid mode. Same behaviour as TRUE, except for: + + 2. Router Solicitations are being sent when necessary. + + Default: 0 (disabled) if global forwarding is disabled (default), + otherwise 1 (enabled). hop_limit - INTEGER Default Hop Limit to set. diff --git a/Documentation/networking/phonet.txt b/Documentation/networking/phonet.txt index 6e8ce09f9c73..cf76608a2d35 100644 --- a/Documentation/networking/phonet.txt +++ b/Documentation/networking/phonet.txt @@ -112,6 +112,22 @@ However, connect() and getpeername() are not supported, as they did not seem useful with Phonet usages (could be added easily). +Resource subscription +--------------------- + +A Phonet datagram socket can be subscribed to any number of 8-bits +Phonet resources, as follow: + + uint32_t res = 0xXX; + ioctl(fd, SIOCPNADDRESOURCE, &res); + +Subscription is similarly cancelled using the SIOCPNDELRESOURCE I/O +control request, or when the socket is closed. + +Note that no more than one socket can be subcribed to any given +resource at a time. If not, ioctl() will return EBUSY. + + Phonet Pipe protocol -------------------- diff --git a/Documentation/networking/timestamping.txt b/Documentation/networking/timestamping.txt index e8c8f4f06c67..98097d8cb910 100644 --- a/Documentation/networking/timestamping.txt +++ b/Documentation/networking/timestamping.txt @@ -172,15 +172,19 @@ struct skb_shared_hwtstamps { }; Time stamps for outgoing packets are to be generated as follows: -- In hard_start_xmit(), check if skb_tx(skb)->hardware is set no-zero. - If yes, then the driver is expected to do hardware time stamping. +- In hard_start_xmit(), check if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) + is set no-zero. If yes, then the driver is expected to do hardware time + stamping. - If this is possible for the skb and requested, then declare - that the driver is doing the time stamping by setting the field - skb_tx(skb)->in_progress non-zero. You might want to keep a pointer - to the associated skb for the next step and not free the skb. A driver - not supporting hardware time stamping doesn't do that. A driver must - never touch sk_buff::tstamp! It is used to store software generated - time stamps by the network subsystem. + that the driver is doing the time stamping by setting the flag + SKBTX_IN_PROGRESS in skb_shinfo(skb)->tx_flags , e.g. with + + skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS; + + You might want to keep a pointer to the associated skb for the next step + and not free the skb. A driver not supporting hardware time stamping doesn't + do that. A driver must never touch sk_buff::tstamp! It is used to store + software generated time stamps by the network subsystem. - As soon as the driver has sent the packet and/or obtained a hardware time stamp for it, it passes the time stamp back by calling skb_hwtstamp_tx() with the original skb, the raw @@ -191,6 +195,6 @@ Time stamps for outgoing packets are to be generated as follows: this would occur at a later time in the processing pipeline than other software time stamping and therefore could lead to unexpected deltas between time stamps. -- If the driver did not call set skb_tx(skb)->in_progress, then +- If the driver did not set the SKBTX_IN_PROGRESS flag (see above), then dev_hard_start_xmit() checks whether software time stamping is wanted as fallback and potentially generates the time stamp. |
