7a54d4a99d
Completely redesigns broadcast link ACK and NACK mechanisms to prevent spurious retransmit requests in dual LAN networks, and to prevent the broadcast link from stalling due to the failure of a receiving node to acknowledge receiving a broadcast message or request its retransmission. Note: These changes only impact the timing of when ACK and NACK messages are sent, and not the basic broadcast link protocol itself, so inter- operability with nodes using the "classic" algorithms is maintained. The revised algorithms are as follows: 1) An explicit ACK message is still sent after receiving 16 in-sequence messages, and implicit ACK information continues to be carried in other unicast link message headers (including link state messages). However, the timing of explicit ACKs is now based on the receiving node's absolute network address rather than its relative network address to ensure that the failure of another node does not delay the ACK beyond its 16 message target. 2) A NACK message is now typically sent only when a message gap persists for two consecutive incoming link state messages; this ensures that a suspected gap is not confirmed until both LANs in a dual LAN network have had an opportunity to deliver the message, thereby preventing spurious NACKs. A NACK message can also be generated by the arrival of a single link state message, if the deferred queue is so big that the current message gap cannot be the result of "normal" mis-ordering due to the use of dual LANs (or one LAN using a bonded interface). Since link state messages typically arrive at different nodes at different times the problem of multiple nodes issuing identical NACKs simultaneously is inherently avoided. 3) Nodes continue to "peek" at NACK messages sent by other nodes. If another node requests retransmission of a message gap suspected (but not yet confirmed) by the peeking node, the peeking node forgets about the gap and does not generate a duplicate retransmit request. (If the peeking node subsequently fails to receive the lost message, later link state messages will cause it to rediscover and confirm the gap and send another NACK.) 4) Message gap "equality" is now determined by the start of the gap only. This is sufficient to deal with the most common cases of message loss, and eliminates the need for complex end of gap computations. 5) A peeking node no longer tries to determine whether it should send a complementary NACK, since the most common cases of message loss don't require it to be sent. Consequently, the node no longer examines the "broadcast tag" field of a NACK message when peeking. Signed-off-by: Allan Stephens <allan.stephens@windriver.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
105 lines
3.6 KiB
C
105 lines
3.6 KiB
C
/*
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* net/tipc/bcast.h: Include file for TIPC broadcast code
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*
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* Copyright (c) 2003-2006, Ericsson AB
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* Copyright (c) 2005, 2010-2011, Wind River Systems
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the names of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _TIPC_BCAST_H
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#define _TIPC_BCAST_H
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#define MAX_NODES 4096
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#define WSIZE 32
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/**
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* struct tipc_node_map - set of node identifiers
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* @count: # of nodes in set
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* @map: bitmap of node identifiers that are in the set
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*/
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struct tipc_node_map {
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u32 count;
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u32 map[MAX_NODES / WSIZE];
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};
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#define PLSIZE 32
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/**
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* struct tipc_port_list - set of node local destination ports
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* @count: # of ports in set (only valid for first entry in list)
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* @next: pointer to next entry in list
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* @ports: array of port references
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*/
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struct tipc_port_list {
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int count;
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struct tipc_port_list *next;
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u32 ports[PLSIZE];
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};
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struct tipc_node;
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extern const char tipc_bclink_name[];
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void tipc_nmap_add(struct tipc_node_map *nm_ptr, u32 node);
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void tipc_nmap_remove(struct tipc_node_map *nm_ptr, u32 node);
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/**
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* tipc_nmap_equal - test for equality of node maps
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*/
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static inline int tipc_nmap_equal(struct tipc_node_map *nm_a, struct tipc_node_map *nm_b)
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{
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return !memcmp(nm_a, nm_b, sizeof(*nm_a));
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}
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void tipc_port_list_add(struct tipc_port_list *pl_ptr, u32 port);
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void tipc_port_list_free(struct tipc_port_list *pl_ptr);
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void tipc_bclink_init(void);
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void tipc_bclink_stop(void);
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void tipc_bclink_add_node(u32 addr);
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void tipc_bclink_remove_node(u32 addr);
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struct tipc_node *tipc_bclink_retransmit_to(void);
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void tipc_bclink_acknowledge(struct tipc_node *n_ptr, u32 acked);
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int tipc_bclink_send_msg(struct sk_buff *buf);
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void tipc_bclink_recv_pkt(struct sk_buff *buf);
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u32 tipc_bclink_get_last_sent(void);
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u32 tipc_bclink_acks_missing(struct tipc_node *n_ptr);
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void tipc_bclink_update_link_state(struct tipc_node *n_ptr, u32 last_sent);
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int tipc_bclink_stats(char *stats_buf, const u32 buf_size);
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int tipc_bclink_reset_stats(void);
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int tipc_bclink_set_queue_limits(u32 limit);
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void tipc_bcbearer_sort(void);
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#endif
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