lib/stp.h

   1 /*
   2  * Copyright (c) 2008, 2011 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef STP_H
  18 #define STP_H 1
  19
  20 /* This is an implementation of Spanning Tree Protocol as described in IEEE
  21  * 802.1D-1998, clauses 8 and 9.  Section numbers refer to this standard.  */
  22
  23 #include <stdbool.h>
  24 #include <stdint.h>
  25 #include "compiler.h"
  26 #include "util.h"
  27
  28 struct ofpbuf;
  29
  30 /* LLC field values used for STP frames. */
  31 #define STP_LLC_SSAP 0x42
  32 #define STP_LLC_DSAP 0x42
  33 #define STP_LLC_CNTL 0x03
  34
  35 /* Bridge and port priorities that should be used by default. */
  36 #define STP_DEFAULT_BRIDGE_PRIORITY 32768
  37 #define STP_DEFAULT_PORT_PRIORITY 128
  38
  39 /* Default time values. */
  40 #define STP_DEFAULT_MAX_AGE    20000
  41 #define STP_DEFAULT_HELLO_TIME 2000
  42 #define STP_DEFAULT_FWD_DELAY  15000
  43
  44 /* Bridge identifier.  Top 16 bits are a priority value (numerically lower
  45  * values are higher priorities).  Bottom 48 bits are MAC address of bridge. */
  46 typedef uint64_t stp_identifier;
  47
  48
  49 #define STP_ID_FMT "%04"PRIx16".%012"PRIx64
  50 #define STP_ID_ARGS(stp_id) \
  51     (uint16_t)((stp_id) >> 48), \
  52     (uint64_t)((stp_id) & 0xffffffffffffULL)
  53
  54 #define STP_PORT_ID_FMT "%04"PRIx16
  55
  56 /* Basic STP functionality. */
  57 #define STP_MAX_PORTS 255
  58 void stp_init(void);
  59 struct stp *stp_create(const char *name, stp_identifier bridge_id,
  60                        void (*send_bpdu)(struct ofpbuf *bpdu, int port_no,
  61                                          void *aux),
  62                        void *aux);
  63 struct stp *stp_ref(const struct stp *);
  64 void stp_unref(struct stp *);
  65 void stp_tick(struct stp *, int ms);
  66 void stp_set_bridge_id(struct stp *, stp_identifier bridge_id);
  67 void stp_set_bridge_priority(struct stp *, uint16_t new_priority);
  68 void stp_set_hello_time(struct stp *, int ms);
  69 void stp_set_max_age(struct stp *, int ms);
  70 void stp_set_forward_delay(struct stp *, int ms);
  71
  72 /* STP properties. */
  73 const char *stp_get_name(const struct stp *);
  74 stp_identifier stp_get_bridge_id(const struct stp *);
  75 stp_identifier stp_get_designated_root(const struct stp *);
  76 bool stp_is_root_bridge(const struct stp *);
  77 int stp_get_root_path_cost(const struct stp *);
  78 int stp_get_hello_time(const struct stp *);
  79 int stp_get_max_age(const struct stp *);
  80 int stp_get_forward_delay(const struct stp *);
  81 bool stp_check_and_reset_fdb_flush(struct stp *);
  82
  83 /* Obtaining STP ports. */
  84 struct stp_port *stp_get_port(struct stp *, int port_no);
  85 struct stp_port *stp_get_root_port(struct stp *);
  86 bool stp_get_changed_port(struct stp *, struct stp_port **portp);
  87
  88 /* State of an STP port.
  89  *
  90  * A port is in exactly one state at any given time, but distinct bits are used
  91  * for states to allow testing for more than one state with a bit mask.
  92  *
  93  * The STP_DISABLED state means that the port is disabled by management.
  94  * In our implementation, this state means that the port does not
  95  * participate in the spanning tree, but it still forwards traffic as if
  96  * it were in the STP_FORWARDING state.  This may be different from
  97  * other implementations.
  98  *
  99  * The following diagram describes the various states and what they are
 100  * allowed to do in OVS:
 101  *
 102  *                     FWD  LRN  TX_BPDU RX_BPDU FWD_BPDU
 103  *                     ---  ---  ------- ------- --------
 104  *        Disabled      Y    -      -       -        Y
 105  *        Blocking      -    -      -       Y        -
 106  *        Listening     -    -      Y       Y        Y
 107  *        Learning      -    Y      Y       Y        Y
 108  *        Forwarding    Y    Y      Y       Y        Y
 109  *
 110  *
 111  * FWD:              the port should forward any incoming non-stp-BPDU
 112  *                   packets.
 113  *
 114  * LRN:              the port should conduct MAC learning on packets received.
 115  *
 116  * TX_BPDU/RX_BPDU:  the port could generate/consume bpdus.
 117  *
 118  * FWD_BPDU:         the port should should always forward the BPDUS,
 119  *                   whether they are generated by the port or received
 120  *                   as incoming packets.
 121  *
 122  * Once again, note that the disabled state forwards traffic, which is
 123  * likely different than the spec would indicate.
 124  */
 125 enum stp_state {
 126     STP_DISABLED = 1 << 0,       /* 8.4.5: See note above. */
 127     STP_LISTENING = 1 << 1,      /* 8.4.2: Not learning or relaying frames. */
 128     STP_LEARNING = 1 << 2,       /* 8.4.3: Learning but not relaying frames. */
 129     STP_FORWARDING = 1 << 3,     /* 8.4.4: Learning and relaying frames. */
 130     STP_BLOCKING = 1 << 4        /* 8.4.1: Initial boot state. */
 131 };
 132 const char *stp_state_name(enum stp_state);
 133 bool stp_forward_in_state(enum stp_state);
 134 bool stp_learn_in_state(enum stp_state);
 135 bool stp_should_forward_bpdu(enum stp_state);
 136
 137 /* Role of an STP port. */
 138 enum stp_role {
 139     STP_ROLE_ROOT,               /* Path to root bridge. */
 140     STP_ROLE_DESIGNATED,         /* Path to LAN segments. */
 141     STP_ROLE_ALTERNATE,          /* Backup path to root bridge. */
 142     STP_ROLE_DISABLED            /* Port does not participate in STP. */
 143 };
 144 const char *stp_role_name(enum stp_role);
 145
 146 void stp_received_bpdu(struct stp_port *, const void *bpdu, size_t bpdu_size);
 147
 148 struct stp *stp_port_get_stp(struct stp_port *);
 149 void stp_port_set_aux(struct stp_port *, void *);
 150 void *stp_port_get_aux(struct stp_port *);
 151 int stp_port_no(const struct stp_port *);
 152 int stp_port_get_id(const struct stp_port *);
 153 enum stp_state stp_port_get_state(const struct stp_port *);
 154 enum stp_role stp_port_get_role(const struct stp_port *);
 155 void stp_port_get_counts(const struct stp_port *,
 156                          int *tx_count, int *rx_count, int *error_count);
 157 void stp_port_enable(struct stp_port *);
 158 void stp_port_disable(struct stp_port *);
 159 void stp_port_set_priority(struct stp_port *, uint8_t new_priority);
 160 uint16_t stp_convert_speed_to_cost(unsigned int speed);
 161 void stp_port_set_path_cost(struct stp_port *, uint16_t path_cost);
 162 void stp_port_set_speed(struct stp_port *, unsigned int speed);
 163 void stp_port_enable_change_detection(struct stp_port *);
 164 void stp_port_disable_change_detection(struct stp_port *);
 165
 166 #endif /* stp.h */