diff options
author | Pekka Enberg <penberg@kernel.org> | 2010-10-24 19:57:05 +0300 |
---|---|---|
committer | Pekka Enberg <penberg@kernel.org> | 2010-10-24 19:57:05 +0300 |
commit | 6d4121f6c20a0e86231d52f535f1c82423b3326f (patch) | |
tree | 5c235cac699ca86b504850aa663ddadde0455a61 /Documentation/networking/dccp.txt | |
parent | 92a5bbc11ff2442a54b2f1d313088c245828ef4e (diff) | |
parent | 35da7a307c535f9c2929cae277f3df425c9f9b1e (diff) |
Merge branch 'master' into for-linus
Conflicts:
include/linux/percpu.h
mm/percpu.c
Diffstat (limited to 'Documentation/networking/dccp.txt')
-rw-r--r-- | Documentation/networking/dccp.txt | 29 |
1 files changed, 23 insertions, 6 deletions
diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt index a62fdf7a6bf..271d524a4c8 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. |