diff options
| -rw-r--r-- | Documentation/networking/dccp.txt | 26 | ||||
| -rw-r--r-- | net/dccp/ccids/ccid2.c | 5 |
2 files changed, 23 insertions, 8 deletions
diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt index a62fdf7..cdb6492 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 +157,27 @@ 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 + + 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/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c index b9c942a..dc18172 100644 --- a/net/dccp/ccids/ccid2.c +++ b/net/dccp/ccids/ccid2.c @@ -325,8 +325,9 @@ static void ccid2_rtt_estimator(struct sock *sk, const long mrtt) hc->tx_srtt = m << 3; hc->tx_mdev = m << 1; - hc->tx_mdev_max = max(TCP_RTO_MIN, hc->tx_mdev); + hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk)); hc->tx_rttvar = hc->tx_mdev_max; + hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; } else { /* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */ @@ -367,7 +368,7 @@ static void ccid2_rtt_estimator(struct sock *sk, const long mrtt) hc->tx_rttvar -= (hc->tx_rttvar - hc->tx_mdev_max) >> 2; hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; - hc->tx_mdev_max = TCP_RTO_MIN; + hc->tx_mdev_max = tcp_rto_min(sk); } } |
