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linux/net/tipc/bearer.h
Jon Paul Maloy 35c55c9877 tipc: add neighbor monitoring framework 
TIPC based clusters are by default set up with full-mesh link
connectivity between all nodes. Those links are expected to provide
a short failure detection time, by default set to 1500 ms. Because
of this, the background load for neighbor monitoring in an N-node
cluster increases with a factor N on each node, while the overall
monitoring traffic through the network infrastructure increases at
a ~(N * (N - 1)) rate. Experience has shown that such clusters don't
scale well beyond ~100 nodes unless we significantly increase failure
discovery tolerance.

This commit introduces a framework and an algorithm that drastically
reduces this background load, while basically maintaining the original
failure detection times across the whole cluster. Using this algorithm,
background load will now grow at a rate of ~(2 * sqrt(N)) per node, and
at ~(2 * N * sqrt(N)) in traffic overhead. As an example, each node will
now have to actively monitor 38 neighbors in a 400-node cluster, instead
of as before 399.

This "Overlapping Ring Supervision Algorithm" is completely distributed
and employs no centralized or coordinated state. It goes as follows:

- Each node makes up a linearly ascending, circular list of all its N
  known neighbors, based on their TIPC node identity. This algorithm
  must be the same on all nodes.

- The node then selects the next M = sqrt(N) - 1 nodes downstream from
  itself in the list, and chooses to actively monitor those. This is
  called its "local monitoring domain".

- It creates a domain record describing the monitoring domain, and
  piggy-backs this in the data area of all neighbor monitoring messages
  (LINK_PROTOCOL/STATE) leaving that node. This means that all nodes in
  the cluster eventually (default within 400 ms) will learn about
  its monitoring domain.

- Whenever a node discovers a change in its local domain, e.g., a node
  has been added or has gone down, it creates and sends out a new
  version of its node record to inform all neighbors about the change.

- A node receiving a domain record from anybody outside its local domain
  matches this against its own list (which may not look the same), and
  chooses to not actively monitor those members of the received domain
  record that are also present in its own list. Instead, it relies on
  indications from the direct monitoring nodes if an indirectly
  monitored node has gone up or down. If a node is indicated lost, the
  receiving node temporarily activates its own direct monitoring towards
  that node in order to confirm, or not, that it is actually gone.

- Since each node is actively monitoring sqrt(N) downstream neighbors,
  each node is also actively monitored by the same number of upstream
  neighbors. This means that all non-direct monitoring nodes normally
  will receive sqrt(N) indications that a node is gone.

- A major drawback with ring monitoring is how it handles failures that
  cause massive network partitionings. If both a lost node and all its
  direct monitoring neighbors are inside the lost partition, the nodes in
  the remaining partition will never receive indications about the loss.
  To overcome this, each node also chooses to actively monitor some
  nodes outside its local domain. Those nodes are called remote domain
  "heads", and are selected in such a way that no node in the cluster
  will be more than two direct monitoring hops away. Because of this,
  each node, apart from monitoring the member of its local domain, will
  also typically monitor sqrt(N) remote head nodes.

- As an optimization, local list status, domain status and domain
  records are marked with a generation number. This saves senders from
  unnecessarily conveying  unaltered domain records, and receivers from
  performing unneeded re-adaptations of their node monitoring list, such
  as re-assigning domain heads.

- As a measure of caution we have added the possibility to disable the
  new algorithm through configuration. We do this by keeping a threshold
  value for the cluster size; a cluster that grows beyond this value
  will switch from full-mesh to ring monitoring, and vice versa when
  it shrinks below the value. This means that if the threshold is set to
  a value larger than any anticipated cluster size (default size is 32)
  the new algorithm is effectively disabled. A patch set for altering the
  threshold value and for listing the table contents will follow shortly.

- This change is fully backwards compatible.

Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-15 14:06:28 -07:00

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/*
* net/tipc/bearer.h: Include file for TIPC bearer code
*
* Copyright (c) 1996-2006, 2013-2016, Ericsson AB
* Copyright (c) 2005, 2010-2011, Wind River Systems
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the names of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* Alternatively, this software may be distributed under the terms of the
* GNU General Public License ("GPL") version 2 as published by the Free
* Software Foundation.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _TIPC_BEARER_H
#define _TIPC_BEARER_H
#include "netlink.h"
#include "core.h"
#include <net/genetlink.h>
#define MAX_MEDIA 3
/* Identifiers associated with TIPC message header media address info
* - address info field is 32 bytes long
* - the field's actual content and length is defined per media
* - remaining unused bytes in the field are set to zero
*/
#define TIPC_MEDIA_INFO_SIZE 32
#define TIPC_MEDIA_TYPE_OFFSET 3
#define TIPC_MEDIA_ADDR_OFFSET 4
/*
* Identifiers of supported TIPC media types
*/
#define TIPC_MEDIA_TYPE_ETH 1
#define TIPC_MEDIA_TYPE_IB 2
#define TIPC_MEDIA_TYPE_UDP 3
/**
* struct tipc_media_addr - destination address used by TIPC bearers
* @value: address info (format defined by media)
* @media_id: TIPC media type identifier
* @broadcast: non-zero if address is a broadcast address
*/
struct tipc_media_addr {
u8 value[TIPC_MEDIA_INFO_SIZE];
u8 media_id;
u8 broadcast;
};
struct tipc_bearer;
/**
* struct tipc_media - Media specific info exposed to generic bearer layer
* @send_msg: routine which handles buffer transmission
* @enable_media: routine which enables a media
* @disable_media: routine which disables a media
* @addr2str: convert media address format to string
* @addr2msg: convert from media addr format to discovery msg addr format
* @msg2addr: convert from discovery msg addr format to media addr format
* @raw2addr: convert from raw addr format to media addr format
* @priority: default link (and bearer) priority
* @tolerance: default time (in ms) before declaring link failure
* @window: default window (in packets) before declaring link congestion
* @type_id: TIPC media identifier
* @hwaddr_len: TIPC media address len
* @name: media name
*/
struct tipc_media {
int (*send_msg)(struct net *net, struct sk_buff *buf,
struct tipc_bearer *b,
struct tipc_media_addr *dest);
int (*enable_media)(struct net *net, struct tipc_bearer *b,
struct nlattr *attr[]);
void (*disable_media)(struct tipc_bearer *b);
int (*addr2str)(struct tipc_media_addr *addr,
char *strbuf,
int bufsz);
int (*addr2msg)(char *msg, struct tipc_media_addr *addr);
int (*msg2addr)(struct tipc_bearer *b,
struct tipc_media_addr *addr,
char *msg);
int (*raw2addr)(struct tipc_bearer *b,
struct tipc_media_addr *addr,
char *raw);
u32 priority;
u32 tolerance;
u32 window;
u32 type_id;
u32 hwaddr_len;
char name[TIPC_MAX_MEDIA_NAME];
};
/**
* struct tipc_bearer - Generic TIPC bearer structure
* @media_ptr: pointer to additional media-specific information about bearer
* @mtu: max packet size bearer can support
* @addr: media-specific address associated with bearer
* @name: bearer name (format = media:interface)
* @media: ptr to media structure associated with bearer
* @bcast_addr: media address used in broadcasting
* @rcu: rcu struct for tipc_bearer
* @priority: default link priority for bearer
* @window: default window size for bearer
* @tolerance: default link tolerance for bearer
* @domain: network domain to which links can be established
* @identity: array index of this bearer within TIPC bearer array
* @link_req: ptr to (optional) structure making periodic link setup requests
* @net_plane: network plane ('A' through 'H') currently associated with bearer
*
* Note: media-specific code is responsible for initialization of the fields
* indicated below when a bearer is enabled; TIPC's generic bearer code takes
* care of initializing all other fields.
*/
struct tipc_bearer {
void __rcu *media_ptr; /* initalized by media */
u32 mtu; /* initalized by media */
struct tipc_media_addr addr; /* initalized by media */
char name[TIPC_MAX_BEARER_NAME];
struct tipc_media *media;
struct tipc_media_addr bcast_addr;
struct rcu_head rcu;
u32 priority;
u32 window;
u32 tolerance;
u32 domain;
u32 identity;
struct tipc_link_req *link_req;
char net_plane;
};
struct tipc_bearer_names {
char media_name[TIPC_MAX_MEDIA_NAME];
char if_name[TIPC_MAX_IF_NAME];
};
/*
* TIPC routines available to supported media types
*/
void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b);
/*
* Routines made available to TIPC by supported media types
*/
extern struct tipc_media eth_media_info;
#ifdef CONFIG_TIPC_MEDIA_IB
extern struct tipc_media ib_media_info;
#endif
#ifdef CONFIG_TIPC_MEDIA_UDP
extern struct tipc_media udp_media_info;
#endif
int tipc_nl_bearer_disable(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_enable(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_dump(struct sk_buff *skb, struct netlink_callback *cb);
int tipc_nl_bearer_get(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_media_dump(struct sk_buff *skb, struct netlink_callback *cb);
int tipc_nl_media_get(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_media_set(struct sk_buff *skb, struct genl_info *info);
int tipc_media_set_priority(const char *name, u32 new_value);
int tipc_media_set_window(const char *name, u32 new_value);
void tipc_media_addr_printf(char *buf, int len, struct tipc_media_addr *a);
int tipc_enable_l2_media(struct net *net, struct tipc_bearer *b,
struct nlattr *attrs[]);
void tipc_disable_l2_media(struct tipc_bearer *b);
int tipc_l2_send_msg(struct net *net, struct sk_buff *buf,
struct tipc_bearer *b, struct tipc_media_addr *dest);
void tipc_bearer_add_dest(struct net *net, u32 bearer_id, u32 dest);
void tipc_bearer_remove_dest(struct net *net, u32 bearer_id, u32 dest);
struct tipc_bearer *tipc_bearer_find(struct net *net, const char *name);
struct tipc_media *tipc_media_find(const char *name);
int tipc_bearer_setup(void);
void tipc_bearer_cleanup(void);
void tipc_bearer_stop(struct net *net);
int tipc_bearer_mtu(struct net *net, u32 bearer_id);
void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id,
struct sk_buff *skb,
struct tipc_media_addr *dest);
void tipc_bearer_xmit(struct net *net, u32 bearer_id,
struct sk_buff_head *xmitq,
struct tipc_media_addr *dst);
void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id,
struct sk_buff_head *xmitq);
#endif /* _TIPC_BEARER_H */
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