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| ds_ht.c | 9 years ago | |
| ds_ht.h | 10 years ago | |
README
DISPATCHER Module
Daniel-Constantin Mierla
<miconda@gmail.com>
Edited by
Daniel-Constantin Mierla
<miconda@gmail.com>
Edited by
Carsten Bock
ng-voice GmbH
Edited by
Olle E. Johansson
Edvina AB
Edited by
Alessandro Arrichiello
Hewlett Packard
Copyright © 2004 FhG FOKUS
Copyright © 2005 Voice Sistem
Copyright © 2010 Daniel-Constantin Mierla (asipto.com)
Copyright © 2014 Olle E. Johansson, Edvina AB
Copyright © 2015 Alessandro Arrichiello, Hewlett Packard
__________________________________________________________________
Table of Contents
1. Admin Guide
1. Overview
2. Dependencies
2.1. Kamailio modules
2.2. External libraries or applications
3. Parameters
3.1. list_file (string)
3.2. db_url (string)
3.3. table_name (string)
3.4. setid_col (string)
3.5. destination_col (string)
3.6. flags_col (string)
3.7. priority_col (string)
3.8. force_dst (int)
3.9. flags (int)
3.10. use_default (int)
3.11. dst_avp (str)
3.12. grp_avp (str)
3.13. cnt_avp (str)
3.14. dstid_avp (str)
3.15. attrs_avp (str)
3.16. sock_avp (str)
3.17. hash_pvar (str)
3.18. setid_pvname (str)
3.19. attrs_pvname (str)
3.20. ds_ping_method (string)
3.21. ds_ping_from (string)
3.22. ds_ping_interval (int)
3.23. ds_probing_threshold (int)
3.24. ds_inactive_threshold (int)
3.25. ds_ping_reply_codes (string)
3.26. ds_probing_mode (int)
3.27. ds_hash_size (int)
3.28. ds_hash_expire (int)
3.29. ds_hash_initexpire (int)
3.30. ds_hash_check_interval (int)
3.31. outbound_proxy (str)
3.32. ds_default_socket (str)
3.33. ds_timer_mode (int)
4. Functions
4.1. ds_select_dst(set, alg[, limit])
4.2. ds_select_domain(set, alg[, limit])
4.3. ds_next_dst()
4.4. ds_next_domain()
4.5. ds_mark_dst([state])
4.6. ds_list_exist(groupid)
4.7. ds_is_from_list([groupid [, mode [, uri] ] ])
4.8. ds_load_update()
4.9. ds_load_unset()
5. MI Commands
5.1. ds_set_state
5.2. ds_list
5.3. ds_reload
6. RPC Commands
6.1. dispatcher.set_state
6.2. dispatcher.list
6.3. dispatcher.reload
6.4. dispatcher.ping_active
7. Installation and Running
7.1. Destination List File
7.1.1. Special Attributes
7.1.2. File Format
7.2. Kamailio config file
8. Event routes
8.1. dispatcher:dst-down
8.2. dispatcher:dst-up
2. Frequently Asked Questions
List of Examples
1.1. Set the “list_file” parameter
1.2. Set “db_url” parameter
1.3. Set “table_name” parameter
1.4. Set “setid_col” parameter
1.5. Set “destination_col” parameter
1.6. Set “flags_col” parameter
1.7. Set “priority_col” parameter
1.8. Set the “force_dst” parameter
1.9. Set the “flags” parameter
1.10. Set the “use_default” parameter
1.11. Set the “dst_avp” parameter
1.12. Set the “grp_avp” parameter
1.13. Set the “cnt_avp” parameter
1.14. Set the “dstid_avp” parameter
1.15. Set the “attrs_avp” parameter
1.16. Set the “sock_avp” parameter
1.17. Use $avp(i:273) for hashing:
1.18. Use combination of PVs for hashing:
1.19. Set the “setid_pvname” parameter
1.20. Set the “attrs_pvname” parameter
1.21. Set the “ds_ping_method” parameter
1.22. Set the “ds_ping_from” parameter
1.23. Set the “ds_ping_interval” parameter
1.24. Set the “ds_probing_threshold” parameter
1.25. Set the “ds_inactive_threshold” parameter
1.26. Set the “ds_ping_reply_codes” parameter
1.27. Set the “ds_probing_mode” parameter
1.28. Set the “ds_hash_size” parameter
1.29. Set the “ds_hash_expire” parameter
1.30. Set the “ds_hash_initexpire” parameter
1.31. Set the “ds_hash_check_interval” parameter
1.32. Set the “outbound_proxy” parameter
1.33. Set the “ds_default_socket” parameter
1.34. Set the “ds_timer_mode” parameter
1.35. ds_select_dst usage
1.36. ds_mark_dst usage
1.37. ds_list_exist usage
1.38. ds_is_from_list usage
1.39. ds_load_unset usage
1.40. dispatcher list file
1.41. Kamailio config script - sample dispatcher usage
Chapter 1. Admin Guide
Table of Contents
1. Overview
2. Dependencies
2.1. Kamailio modules
2.2. External libraries or applications
3. Parameters
3.1. list_file (string)
3.2. db_url (string)
3.3. table_name (string)
3.4. setid_col (string)
3.5. destination_col (string)
3.6. flags_col (string)
3.7. priority_col (string)
3.8. force_dst (int)
3.9. flags (int)
3.10. use_default (int)
3.11. dst_avp (str)
3.12. grp_avp (str)
3.13. cnt_avp (str)
3.14. dstid_avp (str)
3.15. attrs_avp (str)
3.16. sock_avp (str)
3.17. hash_pvar (str)
3.18. setid_pvname (str)
3.19. attrs_pvname (str)
3.20. ds_ping_method (string)
3.21. ds_ping_from (string)
3.22. ds_ping_interval (int)
3.23. ds_probing_threshold (int)
3.24. ds_inactive_threshold (int)
3.25. ds_ping_reply_codes (string)
3.26. ds_probing_mode (int)
3.27. ds_hash_size (int)
3.28. ds_hash_expire (int)
3.29. ds_hash_initexpire (int)
3.30. ds_hash_check_interval (int)
3.31. outbound_proxy (str)
3.32. ds_default_socket (str)
3.33. ds_timer_mode (int)
4. Functions
4.1. ds_select_dst(set, alg[, limit])
4.2. ds_select_domain(set, alg[, limit])
4.3. ds_next_dst()
4.4. ds_next_domain()
4.5. ds_mark_dst([state])
4.6. ds_list_exist(groupid)
4.7. ds_is_from_list([groupid [, mode [, uri] ] ])
4.8. ds_load_update()
4.9. ds_load_unset()
5. MI Commands
5.1. ds_set_state
5.2. ds_list
5.3. ds_reload
6. RPC Commands
6.1. dispatcher.set_state
6.2. dispatcher.list
6.3. dispatcher.reload
6.4. dispatcher.ping_active
7. Installation and Running
7.1. Destination List File
7.1.1. Special Attributes
7.1.2. File Format
7.2. Kamailio config file
8. Event routes
8.1. dispatcher:dst-down
8.2. dispatcher:dst-up
1. Overview
This module offers SIP load balancer functionality and it can be used
as SIP traffic dispatcher. There are many load balancing and traffic
dispaching algorithms that you can choose from, for example:
round-robin, weight based load balancing, call load distribution, and
hashing over SIP message attributes.
The module can be used as a stateless load balancer; it does not depend
on any call state tracking module. It requires the TM module if you
enable auto-discovery of active/inactive gateways.
It is very lightweight, therefore suitable for handling heavy SIP
traffic. As the module has a small footprint and the ability to load
balancing rules from a plain text file, it is suitable for embedded
systems.
2. Dependencies
2.1. Kamailio modules
2.2. External libraries or applications
2.1. Kamailio modules
The following modules must be loaded before this module:
* TM - only if active recovery of failed hosts is required.
* database engine - only if you want to load balancing routes from
database instead of plain text file. .
2.2. External libraries or applications
The following libraries or applications must be installed before
running Kamailio with this module:
* none.
3. Parameters
3.1. list_file (string)
3.2. db_url (string)
3.3. table_name (string)
3.4. setid_col (string)
3.5. destination_col (string)
3.6. flags_col (string)
3.7. priority_col (string)
3.8. force_dst (int)
3.9. flags (int)
3.10. use_default (int)
3.11. dst_avp (str)
3.12. grp_avp (str)
3.13. cnt_avp (str)
3.14. dstid_avp (str)
3.15. attrs_avp (str)
3.16. sock_avp (str)
3.17. hash_pvar (str)
3.18. setid_pvname (str)
3.19. attrs_pvname (str)
3.20. ds_ping_method (string)
3.21. ds_ping_from (string)
3.22. ds_ping_interval (int)
3.23. ds_probing_threshold (int)
3.24. ds_inactive_threshold (int)
3.25. ds_ping_reply_codes (string)
3.26. ds_probing_mode (int)
3.27. ds_hash_size (int)
3.28. ds_hash_expire (int)
3.29. ds_hash_initexpire (int)
3.30. ds_hash_check_interval (int)
3.31. outbound_proxy (str)
3.32. ds_default_socket (str)
3.33. ds_timer_mode (int)
3.1. list_file (string)
Path to the file with destination sets.
Default value is “/etc/kamailio/dispatcher.list” or
“/usr/local/etc/kamailio/dispatcher.list”.
Example 1.1. Set the “list_file” parameter
...
modparam("dispatcher", "list_file", "/var/run/kamailio/dispatcher.list")
...
3.2. db_url (string)
If you want to load the sets of gateways from the database you must set
this parameter.
Default value is “NULL” (disable DB support).
Example 1.2. Set “db_url” parameter
...
modparam("dispatcher", "db_url", "mysql://user:passwb@localhost/database")
...
3.3. table_name (string)
If you want to load the sets of gateways from the database you must set
this parameter as the database name.
Default value is “dispatcher”.
Example 1.3. Set “table_name” parameter
...
modparam("dispatcher", "table_name", "my_dispatcher")
...
3.4. setid_col (string)
The column's name in the database storing the gateway's group id.
Default value is “setid”.
Example 1.4. Set “setid_col” parameter
...
modparam("dispatcher", "setid_col", "groupid")
...
3.5. destination_col (string)
The column's name in the database storing the destination sip URI.
Default value is “destination”.
Example 1.5. Set “destination_col” parameter
...
modparam("dispatcher", "destination_col", "uri")
...
3.6. flags_col (string)
The column's name in the database storing the flags for the destination
URI.
Default value is “flags”.
Example 1.6. Set “flags_col” parameter
...
modparam("dispatcher", "flags_col", "dstflags")
...
3.7. priority_col (string)
The column's name in the database storing the priority for destination
URI.
Default value is “priority”.
Example 1.7. Set “priority_col” parameter
...
modparam("dispatcher", "priority_col", "dstpriority")
...
3.8. force_dst (int)
If set to 1, force overwriting of destination address (outbound proxy)
when that is already set. If set to 0, will return error when the
destination address is already set.
Default value is “1”.
Example 1.8. Set the “force_dst” parameter
...
modparam("dispatcher", "force_dst", 1)
...
3.9. flags (int)
Various flags that affect dispatcher's behaviour. The flags are defined
as a bitmask on an integer value. If flag 1 is set only the username
part of the URI will be used when computing an URI based hash. If no
flags are set the username, hostname and port will be used. The port is
used only if different from 5060 (normal sip URI) or 5061 (in the sips:
case).
If flag 2 is set, then failover support is enabled. The functions
exported by the module will store the rest of addresses from the
destination set in the AVP, and use these AVPs to contact next address
if the current-tried destination fails.
Default value is “0”.
Example 1.9. Set the “flags” parameter
...
modparam("dispatcher", "flags", 3)
...
3.10. use_default (int)
If the parameter is set to 1, the last address in destination set is
used as a final option to send the request to. For example, it is
useful when wanting to send the call to an anouncement server saying:
"the gateways are full, try later".
Default value is “0”.
Example 1.10. Set the “use_default” parameter
...
modparam("dispatcher", "use_default", 1)
...
3.11. dst_avp (str)
The name of the avp which will hold the list with addresses, in the
order they have been selected by the chosen algorithm. If use_default
is 1, the value of last dst_avp_id is the last address in destination
set. The first dst_avp_id is the selected destinations. All the other
addresses from the destination set will be added in the avp list to be
able to implement serial forking.
Note
You must set this parameter if you want to do load balancing fail over.
Default value is “null” - don't add AVPs.
Example 1.11. Set the “dst_avp” parameter
...
modparam("dispatcher", "dst_avp", "$avp(dsdst)")
...
3.12. grp_avp (str)
The name of the avp storing the group id of the destination set. Good
to have it for later usage or checks.
Note
You must set this parameter if you want to do load balancing fail over.
Default value is “null” - don't add AVP.
Example 1.12. Set the “grp_avp” parameter
...
modparam("dispatcher", "grp_avp", "$avp(dsgrp)")
...
3.13. cnt_avp (str)
The name of the avp storing the number of destination addresses kept in
dst_avp AVPs.
Note
You must set this parameter if you want to do load balancing fail over.
Default value is “null” - don't add AVP.
Example 1.13. Set the “cnt_avp” parameter
...
modparam("dispatcher", "cnt_avp", "$avp(dscnt)")
...
3.14. dstid_avp (str)
The name of the avp storing the destination unique ID used for call
load based dispatching.
Note
You must set this parameter if you want to do load balancing on call
load (alg 10).
Default value is “null” - don't add AVP.
Example 1.14. Set the “dstid_avp” parameter
...
modparam("dispatcher", "dstid_avp", "$avp(dsdstid)")
...
3.15. attrs_avp (str)
The name of the avp storing destination's attributes value.
Note
Default value is “null” - don't add AVP.
Example 1.15. Set the “attrs_avp” parameter
...
modparam("dispatcher", "attrs_avp", "$avp(dsattrs)")
...
3.16. sock_avp (str)
The name of the avp which will hold the list with the sockets
associated to the addresses stored in dst_avp avp.
Note
If you want to do load balancing fail over, you have to set this
parameter to use the correct socket for each gateway.
Default value is “null” - don't add AVPs.
Example 1.16. Set the “sock_avp” parameter
...
modparam("dispatcher", "sock_avp", "$avp(dssocket)")
...
3.17. hash_pvar (str)
String with PVs used for the hashing algorithm 7.
Note
You must set this parameter if you want do hashing over custom message
parts.
Default value is “null” - disabled.
Example 1.17. Use $avp(i:273) for hashing:
...
modparam("dispatcher", "hash_pvar", "$avp(i:273)")
...
Example 1.18. Use combination of PVs for hashing:
...
modparam("dispatcher", "hash_pvar", "hash the $fU@$ci")
...
3.18. setid_pvname (str)
The name of the PV where to store the set ID (group ID) when calling
ds_is_from_list() with no parameter.
Default value is “null” - don't set PV.
Example 1.19. Set the “setid_pvname” parameter
...
modparam("dispatcher", "setid_pvname", "$var(setid)")
...
3.19. attrs_pvname (str)
The name of the PV where to store the attributes of matching address
when calling ds_is_from_list().
Default value is “null” - don't set PV.
Example 1.20. Set the “attrs_pvname” parameter
...
modparam("dispatcher", "attrs_pvname", "$var(attrs)")
...
3.20. ds_ping_method (string)
With this method you can define, with which method you want to probe
the gateways. Pinging gateways feature depends on ds_ping_interval
parameter.
Default value is “OPTIONS”.
Example 1.21. Set the “ds_ping_method” parameter
...
modparam("dispatcher", "ds_ping_method", "INFO")
...
3.21. ds_ping_from (string)
With this Method you can define the "From:"-Line for the request, sent
to the failed gateways. This method is only available, if compiled with
the probing of failed gateways enabled.
Default value is “sip:dispatcher@localhost”.
Example 1.22. Set the “ds_ping_from” parameter
...
modparam("dispatcher", "ds_ping_from", "sip:proxy@sip.somehost.com")
...
3.22. ds_ping_interval (int)
With this parameter you can define the interval for sending a request
to a gateway marked as inactive upon a failed request routing to it.
This parameter is only used, when the TM-Module is loaded. If set to
“0”, the pinging of inactive gateway is disabled.
Default value is “0”.
Example 1.23. Set the “ds_ping_interval” parameter
...
modparam("dispatcher", "ds_ping_interval", 30)
...
3.23. ds_probing_threshold (int)
If you want to set a gateway into inactive mode, there can be a
specific number of failed requests until it will change from "active"
to "inactive". It is using the state "trying", that allows selection of
gateway but indicates there was a failure previously with the gateway.
The number of attempts can be set with this parameter. This parameter
can be modified via ser config framework.
Default value is “1” (set inactive with first failure).
Example 1.24. Set the “ds_probing_threshold” parameter
...
modparam("dispatcher", "ds_probing_threshold", 10)
...
3.24. ds_inactive_threshold (int)
If you want to set a gateway into active mode (after being inactive),
there can be a specific number of successful requests until it will
change from "inactive" to "active". The number of attempts can be set
with this parameter. This parameter can be modified via ser config
framework.
Default value is “1” (set active with first success).
Example 1.25. Set the “ds_inactive_threshold” parameter
...
modparam("dispatcher", "ds_inactive_threshold", 10)
...
3.25. ds_ping_reply_codes (string)
This parameter defines the valid response codes, which are accepted as
a valid reply to the PING-Method. It is a list separated by colons,
whery you may define either a single code (e.g. "code=202" would accept
202 as an additional, valid response) or a class of responses, you want
to accept (e.g. "class=2" would accept everything from 200 to 299 as
valid response). This parameter can be modified via ser config
framework.
Please note that the response codes the module accepts as valid reply
to the PING-Method are not only the ones generated from the remote
servers, but also those that are generated locally. E.g.: setting
code=408 or class=400 will never set a backend down even if it is,
because internally the Kamailio transaction layer generates a 408 in
the case of no response from the remote server, and this internal code
408 is accepted as valid value.
Default value is “” (only 200 OK is accepted).
Example 1.26. Set the “ds_ping_reply_codes” parameter
...
modparam("dispatcher", "ds_ping_reply_codes", "class=2;code=403;code=488;class=
3")
...
3.26. ds_probing_mode (int)
Controls what gateways are tested to see if they are reachable.
* Value 0: If set to 0, only the gateways with state PROBING are
tested. After a gateway is probed, the PROBING state is cleared in
this mode.
* Value 1: If set to 1, all gateways are tested. If set to 1 and
there is a failure of keepalive to an active gateway, then it is
set to TRYING state.
* Value 2: if set to 2, only gateways in inactive state with probing
mode set are tested.
* Value 3: If set to 3, any gateway with state PROBING is continually
probed without modifying/removing the PROBING state. This allows
selected gateways to be probed continually, regardless of state
changes.
Default value is “0”.
Example 1.27. Set the “ds_probing_mode” parameter
...
modparam("dispatcher", "ds_probing_mode", 1)
...
3.27. ds_hash_size (int)
The value to be used as power of two to set the number of slots to hash
table storing data for call load dispatching (e.g., value 8 will create
a hash table with 256 slots). It must be greater than 0 to enable call
load dispatching feature (alg 10).
Default value is “0”.
Example 1.28. Set the “ds_hash_size” parameter
...
modparam("dispatcher", "ds_hash_size", 9)
...
3.28. ds_hash_expire (int)
Expiration time in seconds to remove the load on a destination if no
BYE was received meanwhile.
Default value is “7200”.
Example 1.29. Set the “ds_hash_expire” parameter
...
modparam("dispatcher", "ds_hash_expire", 3600)
...
3.29. ds_hash_initexpire (int)
Expiration time in seconds to remove the load on a destination if no
200 for INVITE was received meanwhile and state updated with
ds_load_update().
Default value is “7200”.
Example 1.30. Set the “ds_hash_initexpire” parameter
...
modparam("dispatcher", "ds_hash_initexpire", 60)
...
3.30. ds_hash_check_interval (int)
Time interval in seconds to scan internal hash table with call load
dispatching data for expired items.
Default value is “30”.
Example 1.31. Set the “ds_hash_check_interval” parameter
...
modparam("dispatcher", "ds_hash_check_interval", 60)
...
3.31. outbound_proxy (str)
SIP URI of outbound proxy to be used when sending pings.
By default no outbound proxy is defined.
Example 1.32. Set the “outbound_proxy” parameter
...
modparam("dispatcher", "outbound_proxy", "sip:outbound.example.com")
...
3.32. ds_default_socket (str)
Default socket to be used for sending pings and dispatching requests
when a gateway has no send socket configured.
By default no default socket is defined, the first configuration script
listen directive is used.
Example 1.33. Set the “ds_default_socket” parameter
...
modparam("dispatcher", "ds_default_socket", "udp:192.168.0.125:5060")
...
3.33. ds_timer_mode (int)
Specify the timer process to be used by the module for keepalives and
active dialogs tracking.
It can be set to:
* 0 - use main timer process.
* 1 - use secondary timer process.
On a server with a lot of traffic, using secondary timer can help with
performances, because the main timer can be overloaded by taking care
of transactions retransmissions and expirations of items in memory.
Default value is “0”.
Example 1.34. Set the “ds_timer_mode” parameter
...
modparam("dispatcher", "ds_timer_mode", 1)
...
4. Functions
4.1. ds_select_dst(set, alg[, limit])
4.2. ds_select_domain(set, alg[, limit])
4.3. ds_next_dst()
4.4. ds_next_domain()
4.5. ds_mark_dst([state])
4.6. ds_list_exist(groupid)
4.7. ds_is_from_list([groupid [, mode [, uri] ] ])
4.8. ds_load_update()
4.9. ds_load_unset()
4.1. ds_select_dst(set, alg[, limit])
The method selects a destination from addresses set. It returns true if
a new destination is set. The selected address is set to dst_uri field
(aka the outbound proxy address or the $du variable), not being visible
in the SIP request.
If the bit 2 in 'flags' parameter is set, the rest of the addresses
from the destination set is stored in AVP list (limited with an
optional 'limit' parameter). You can use 'ds_next_dst()' to use next
address in order to achieve serial forking to all possible
destinations.
Meaning of the parameters is as follows:
* set - the id of the set from where to pick up destination address.
It is the first column in destination list file. The parameter can
be an integer or a variable holding an integer.
* alg - the algorithm used to select the destination address. The
parameter can be an integer or a variable holding an interger.
+ “0” - hash over callid
+ “1” - hash over from URI.
+ “2” - hash over to URI.
+ “3” - hash over request-URI.
+ “4” - round-robin (next destination).
+ “5” - hash over authorization-username (Proxy-Authorization or
"normal" authorization). If no username is found, round robin
is used.
+ “6” - random destination (using rand()).
+ “7” - hash over the content of PVs string. Note: This works
only when the parameter hash_pvar is set.
+ “8” - select destination sorted by priority attribute value
(serial forking ordered by priority).
+ “9” - use weight based load distribution. You have to set the
attribute 'weight' per each address in destination set.
+ “10” - use call load distribution. You have to set the
attribute 'duid' (as an unique string id) per each address in
destination set. Also, you must set parameters 'dstid_avp' and
'ds_hash_size'.
The algorithm can be used even with stateless proxy mode,
there is no SIP dialog tracking depending on other modules,
just an internal lightweight call tracking by Call-Id, thus is
fast and suitable even for embedded systems.
The first destination selected by this algorithm is the one
that has the least number of calls associated. The rest of the
destination list is taken in order of the entries in set -
anyhow, until a re-route to next destination happens, the load
on each address can change.
This algorithm can be used only for dispatching INVITE
requests as it is the only SIP method creating a SIP call.
+ “11” - use relative weight based load distribution. You have
to set the attribute 'rweight' per each address in destination
set. Active host usage probability is rweight/(SUM of all
active host rweights in destination group).
The major difference from the weight distribution is the
probability recalculation according to rweight value in case
of host enabling/disabling
For example, 100 calls in 3-hosts group with rweight params
1/2/1 will be distributed as 25/50/25. After third host
failing distribution will be changed to 33/67/0.
+ “X” - if the algorithm is not implemented, the first entry in
set is chosen.
* limit - the maximum number of items to be stored in AVP list for
further failovers (the first selected destination and default
destination are the first to be put in the list)
If the bit 2 in 'flags' is set, the rest of the addresses from the
destination set is stored in AVP list. You can use 'ds_next_dst()' to
use next address to achieve serial forking to all possible
destinations.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.35. ds_select_dst usage
...
ds_select_dst("1", "0");
...
$var(a) = 4;
ds_select_dst("1", "$var(a)");
...
ds_select_dst("1", "4", "3");
...
4.2. ds_select_domain(set, alg[, limit])
The method selects a destination from addresses set and rewrites the
host and port from R-URI. The parameters have same meaning as for
ds_select_dst().
If the bit 2 in 'flags' is set, the rest of the addresses from the
destination set is stored in AVP list (limited with an optional 'limit'
parameter). You can use 'ds_next_domain()' to use next address to
achieve serial forking to all possible destinations.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
4.3. ds_next_dst()
Takes the next destination address from the AVPs with id 'dst_avp_id'
and sets the dst_uri (outbound proxy address).
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
4.4. ds_next_domain()
Takes the next destination address from the AVPs with id 'dst_avp_id'
and sets the domain part of the request URI.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
4.5. ds_mark_dst([state])
Mark the last used address from destination set as inactive ("i"/"I"),
active ("a"/"A"), disabled ("d"/"D") or trying ("t"/"T"). Apart of
disabled state, a destination can be set in probing mode by adding
("p"/"P") flag. With this function, an automatic detection of failed
gateways can be implemented. When an address is marked as inactive or
disabled, it will be ignored by 'ds_select_dst' and 'ds_select_domain'.
The parameter state is optional, when it is missing, then the
destination will be marked inactive (i.e., same as 'i').
Possible values for state parameter:
* "a" or "A" - the last destination should be set to active and the
error-counter should set to "0".
* "i" or "I" - the last destination should be set to inactive and
will be ignored in future requests.
* "t" or "T" - the last destination should be set to temporary trying
state and failure counter is incremented. When the failure counter
reaches the threshold, the destination will be set inactive.
* "p" and "P" - this has to be used in addition to one of the
previous flags - the last destination will be set to probing. This
mean the destination will be pinged with SIP OPTIONS requests from
time to time to detect if it is up or down.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.36. ds_mark_dst usage
...
failure_route[tryagain] {
...
if(t_check_status("500"))
ds_mark_dst("ip"); # set to inactive and probing
...
}
...
4.6. ds_list_exist(groupid)
Check if a specific group is defined in dispatcher list or database.
* groupid - A group ID to check.
This function can be used from ANY_ROUTE.
Example 1.37. ds_list_exist usage
...
if(ds_list_exist("10")) {
...
}
...
4.7. ds_is_from_list([groupid [, mode [, uri] ] ])
This function returns true, if there is a match of source address or
uri with an address in the given group of the dispatcher-list;
otherwise false.
Description of parameters:
* groupid (optional) - if not given or its value is -1, the matching
will be done over all addresses in all dispacher groups. Otherwise
the matching will be done only against the addresses in the
specific group id. The parameter can be an integer or a variable
holding an integer value.
* mode - (optional) - a bitmask to specify how the matching should be
done. If is 0, all ip, port and proto are matched. If bit one is
set, then port is ignored. If bit two is set, then protocol is
ignored. The parameter can be an integer or a variable holding an
integer value. It must be provided if the uri parameter is
provided.
* uri (optional) - if is empty or missing, the matching is done
against source IP, port and protocol. Otherwise the value has to be
a valid SIP URI, used to match against addresses in the dispatcher
list. Only IP, port and protocol are matches, any additional
parameters are ignored. The parameter can be a static or dynamic
(with variables) string. The domain part of the URI can be an IP
address or a hostname.
Upon a match, the variable specified by 'setid_pvname' parameter will
be set to groupid of matching address and the attributes will be set in
variable specified by 'attrs_pvname'.
Note that for backward compatibility mode, when no parameter is given
or only groupid is given, the matching is done only for IP address and
port (protocol is ignored).
This function can be used from ANY_ROUTE.
Example 1.38. ds_is_from_list usage
...
if(ds_is_from_list()) {
...
}
if(ds_is_from_list("10")) {
...
}
if(ds_is_from_list("10", "3")) {
...
}
if(ds_is_from_list("10", "3", "sip:127.0.0.1:5080")) {
...
}
...
4.8. ds_load_update()
Updates the load state:
* if it is a BYE or CANCEL - remove the load from destination address
used to forward the INVITE
* if it is a reply to INVITE - set internal state to confirmed for
call load structure when reply code is 2xx.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
BRANCH_ROUTE and ONREPLY_ROUTE.
4.9. ds_load_unset()
Remove the call load for the destination that routed the call.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
BRANCH_ROUTE and ONREPLY_ROUTE.
Example 1.39. ds_load_unset usage
...
route {
...
if(is_method("BYE|CANCEL"))
ds_load_update();
...
ds_select_dst("1", "10");
...
}
onreply_route {
...
if(is_method("INVITE")
{
if(status=~"2[0-9][0-9]")
ds_load_update();
else if(status=~"[3-7][0-9][0-9]")
ds_load_unset();
}
...
}
...
5. MI Commands
5.1. ds_set_state
5.2. ds_list
5.3. ds_reload
5.1. ds_set_state
Sets the status for a destination address (can be use to mark the
destination as active or inactive).
Name: ds_set_state
Parameters:
* _state_ : state of the destination address
+ “a”: active
+ “i”: inactive
+ “t”: trying
+ “d”: disabled
The states “a”, “i” or “t” can be followed by “p” to set probing
mode (e.g. 'ap', 'ip' or 'tp').
* _group_: destination group id
* _address_: address of the destination in the _group_
MI FIFO Command Format:
:ds_set_state:_reply_fifo_file_
_state_
_group_
_address_
_empty_line_
5.2. ds_list
It lists the groups and included destinations.
Name: ds_list
Parameters: none
MI FIFO Command Format:
:ds_list:_reply_fifo_file_
_empty_line_
5.3. ds_reload
It reloads the groups and included destinations. For algorithm 10 (call
load distribution), old internal list of active calls is destroyed
(because it is bould to the previous list of gateways), meaning that
the module is starting to count active calls again from 0.
Name: ds_reload
Parameters: none
MI DATAGRAM Command Format:
":ds_reload:\n."
6. RPC Commands
6.1. dispatcher.set_state
6.2. dispatcher.list
6.3. dispatcher.reload
6.4. dispatcher.ping_active
6.1. dispatcher.set_state
Sets the state for a destination address (can be use to mark the
destination as active or inactive).
Name: dispatcher.set_state
Parameters:
* _state_ : state of the destination address
+ “a”: active
+ “i”: inactive
+ “t”: trying
+ “d”: disabled
The states “a”, “i” or “t” can be followed by “p” to set probing
mode (e.g. 'ap', 'ip' or 'tp').
* _group_: destination group id
* _address_: address of the destination in the _group_
Example:
...
# prototype: kamcmd dispatcher.set_state _state_ _group_ _address_
kamcmd dispatcher.set_state ip 2 sip:127.0.0.1:5080
...
6.2. dispatcher.list
Lists the groups and included destinations.
Name: dispatcher.list
Parameters: none
Example:
kamcmd dispatcher.list
6.3. dispatcher.reload
Reloads the groups and included destinations. The command is disabled
for call load based dispatching (algorithm 10) since removal of
destinations may leave the list of active calls with broken references.
Name: dispatcher.reload
Parameters: none
Example
kamcmd dispatcher.reload
6.4. dispatcher.ping_active
Sets the global state for sending keepalive requests to destinations.
Name: dispatcher.ping_active
Parameters:
* _state_ : state of sending keepalives
+ “0”: inactive (don't send)
+ “1”: active (send)
If the state parameter is missing, the current state is returned. When
state is changed, new and old values of the state are returned. Default
value for state is 1.
Example:
...
# prototype: kamcmd dispatcher.ping_active _state_
kamcmd dispatcher.ping_active 0
...
7. Installation and Running
7.1. Destination List File
7.1.1. Special Attributes
7.1.2. File Format
7.2. Kamailio config file
7.1. Destination List File
Each destination point must be on one line. First token is the set id
(an integer value), followed by destination address (s string value in
SIP URI format).
Optionally, these fields can be followed by:
* flags (listed by index - can be bitwise mask of values): 0 (value
1) - inactive destination; 1 (value 2) - temporary trying
destination (in the way to become inactive if it does not reply to
keepalives - there is a module parameter to set the threshold of
failures); 2 (value 4) - admin disabled destination; 3 (value 8) -
probing destination (sending keep alives);
* priority: sets the priority in destination list (based on it is
done the initial ordering inside the set)
* attributes: extra fields in form of name1=value1;...;nameN=valueN.
7.1.1. Special Attributes
There are some predefined names:
* 'duid' - used for call load dispatching. It must be an unique value
to identify a destination (gateway address). Practically the load
within the group is associated with this value.
* 'maxload' - used for call load dispatching. It must be a positive
integer, defining the upper limit of active calls per destination.
When the limit is reached, then the gateway is no longer selected
for new calls until an exiting call via that gateway is terminated.
If set to 0, then no active call limit is used.
* 'weight' - used for weight based load distribution. It must be set
to a positive integer value beteen 0 and 100. The value represents
the percent of calls to be sent to that gateways.
* 'rweight' - used for relative weight based load distribution. It
must be set to a positive integer value between 1 and 100
(otherwise host will be excluded from relative weight distribution
type).
* 'socket' - used to set the sending socket for the gateway. It is
used for sending the SIP traffic as well as OPTIONS keepalives.
7.1.2. File Format
Line format is:
...
setid(int) destination(sip uri) flags(int,opt) priority(int,opt) attrs(str,opt)
...
Full line example:
...
1 sip:127.0.0.1:5080 0 0 duid=abc;socket=udp:192.168.0.125:5060;my=xyz
...
For database, each element of a line resides in a different column.
Next is a dispatcher.list file example:
Example 1.40. dispatcher list file
...
# $Id$
# dispatcher destination sets
#
# line format
# setit(int) destination(sip uri) flags(int,opt) priority(int,opt) attributes(st
r,opt)
# proxies
2 sip:127.0.0.1:5080
2 sip:127.0.0.1:5082
# gateways
1 sip:127.0.0.1:7070
1 sip:127.0.0.1:7072
1 sip:127.0.0.1:7074
...
7.2. Kamailio config file
Next listing shows a sample config for using the dispatcher module.
Example 1.41. Kamailio config script - sample dispatcher usage
...
#!KAMAILIO
#
# sample config file for dispatcher module
# - load balancing of VoIP calls with round robin
# - no TPC listening
# - don't dispatch REGISTER and presence requests
#
# Kamailio SIP Server
# - web: http://www.kamailio.org
# - git: http://github.com/kamailio/
#
# Direct your questions about this file to: sr-users@lists.sip-router.org
#
# Refer to the Core CookBook at http://www.kamailio.org/dokuwiki/doku.php
# for an explanation of possible statements, functions and parameters.
#
# Several features can be enabled using '#!define WITH_FEATURE' directives:
#
# *** To run in debug mode:
# - define WITH_DEBUG
#
#!ifndef DBURL
#!define DBURL "mysql://kamailio:kamailiorw@localhost/kamailio"
#!endif
# - flags
# FLT_ - per transaction (message) flags
# FLB_ - per branch flags
#!define FLT_ACC 1
#!define FLT_ACCMISSED 2
#!define FLT_ACCFAILED 3
####### Global Parameters #########
#!ifdef WITH_DEBUG
debug=4
log_stderror=yes
#!else
debug=2
log_stderror=no
#!endif
memdbg=5
memlog=5
log_facility=LOG_LOCAL0
fork=yes
children=4
/* comment the next line to enable TCP */
disable_tcp=yes
/* uncomment the next line to disable the auto discovery of local aliases
based on revers DNS on IPs (default on) */
auto_aliases=no
/* add local domain aliases */
# alias="mysipserver.com"
port=5060
/* uncomment and configure the following line if you want Kamailio to
bind on a specific interface/port/proto (default bind on all available) */
# listen=udp:127.0.0.1:5060
sip_warning=no
####### Modules Section ########
# set module path
mpath="/usr/local/lib/kamailio/modules/"
loadmodule "db_mysql.so"
loadmodule "mi_fifo.so"
loadmodule "kex.so"
loadmodule "tm.so"
loadmodule "tmx.so"
loadmodule "sl.so"
loadmodule "rr.so"
loadmodule "pv.so"
loadmodule "maxfwd.so"
loadmodule "textops.so"
loadmodule "siputils.so"
loadmodule "xlog.so"
loadmodule "sanity.so"
loadmodule "ctl.so"
loadmodule "mi_rpc.so"
loadmodule "acc.so"
loadmodule "dispatcher.so"
# ----------------- setting module-specific parameters ---------------
# ----- rr params -----
# add value to ;lr param to cope with most of the UAs
modparam("rr", "enable_full_lr", 1)
# do not append from tag to the RR (no need for this script)
modparam("rr", "append_fromtag", 0)
# ----- acc params -----
modparam("acc", "log_flag", FLT_ACC)
modparam("acc", "failed_transaction_flag", FLT_ACCFAILED)
modparam("acc", "log_extra",
"src_user=$fU;src_domain=$fd;dst_ouser=$tU;dst_user=$rU;dst_domain=$rd;s
rc_ip=$si")
# ----- tm params -----
modparam("tm", "fr_timer", 2000)
modparam("tm", "fr_inv_timer", 40000)
# ----- dispatcher params -----
modparam("dispatcher", "db_url", DBURL)
modparam("dispatcher", "table_name", "dispatcher")
modparam("dispatcher", "flags", 2)
modparam("dispatcher", "dst_avp", "$avp(AVP_DST)")
modparam("dispatcher", "grp_avp", "$avp(AVP_GRP)")
modparam("dispatcher", "cnt_avp", "$avp(AVP_CNT)")
modparam("dispatcher", "sock_avp", "$avp(AVP_SOCK)")
####### Routing Logic ########
# main request routing logic
request_route {
# per request initial checks
route(REQINIT);
# handle requests within SIP dialogs
route(WITHINDLG);
### only initial requests (no To tag)
# CANCEL processing
if (is_method("CANCEL"))
{
if (t_check_trans())
t_relay();
exit;
}
# handle retransmissions
if(t_precheck_trans()) {
t_check_trans();
exit;
}
t_check_trans();
# record routing for dialog forming requests (in case they are routed)
# - remove preloaded route headers
remove_hf("Route");
if (is_method("INVITE|SUBSCRIBE"))
record_route();
# account only INVITEs
if (is_method("INVITE")) {
setflag(FLT_ACC); # do accounting
}
# handle presence related requests
route(PRESENCE);
# handle registrations
route(REGISTRAR);
if ($rU==$null) {
# request with no Username in RURI
sl_send_reply("484","Address Incomplete");
exit;
}
# dispatch destinations
route(DISPATCH);
}
route[RELAY] {
if (!t_relay()) {
sl_reply_error();
}
exit;
}
# Per SIP request initial checks
route[REQINIT] {
if (!mf_process_maxfwd_header("10")) {
sl_send_reply("483","Too Many Hops");
exit;
}
if(!sanity_check("1511", "7")) {
xlog("Malformed SIP message from $si:$sp\n");
exit;
}
}
# Handle requests within SIP dialogs
route[WITHINDLG] {
if (has_totag()) {
# sequential request withing a dialog should
# take the path determined by record-routing
if (loose_route()) {
if (is_method("BYE")) {
setflag(FLT_ACC); # do accounting ...
setflag(FLT_ACCFAILED); # ... even if the transa
ction fails
}
route(RELAY);
} else {
if (is_method("SUBSCRIBE") && uri == myself) {
# in-dialog subscribe requests
route(PRESENCE);
exit;
}
if ( is_method("ACK") ) {
if ( t_check_trans() ) {
# non loose-route, but stateful ACK;
# must be ACK after a 487 or e.g. 404 fr
om upstream server
t_relay();
exit;
} else {
# ACK without matching transaction ... i
gnore and discard.
exit;
}
}
sl_send_reply("404","Not here");
}
exit;
}
}
# Handle SIP registrations
route[REGISTRAR] {
if(!is_method("REGISTER"))
return;
sl_send_reply("404", "No registrar");
exit;
}
# Presence server route
route[PRESENCE] {
if(!is_method("PUBLISH|SUBSCRIBE"))
return;
sl_send_reply("404", "Not here");
exit;
}
# Dispatch requests
route[DISPATCH] {
# round robin dispatching on gateways group '1'
if(!ds_select_dst("1", "4")) {
send_reply("404", "No destination");
exit;
}
xlog("L_DBG", "--- SCRIPT: going to <$ru> via <$du>\n");
t_on_failure("RTF_DISPATCH");
route(RELAY);
exit;
}
# Try next destionations in failure route
failure_route[RTF_DISPATCH] {
if (t_is_canceled()) {
exit;
}
# next DST - only for 500 or local timeout
if (t_check_status("500")
or (t_branch_timeout() and !t_branch_replied())) {
if(ds_next_dst()) {
t_on_failure("RTF_DISPATCH");
route(RELAY);
exit;
}
}
}
...
8. Event routes
8.1. dispatcher:dst-down
8.2. dispatcher:dst-up
8.1. dispatcher:dst-down
When defined, the module calls event_route[dispatcher:ds-down] when a
destination goes down (becomes probing). A typical use case is to
update NMC equipment as to the status of a destination.
...
event_route[dispatcher:dst-down] {
xlog("L_ERR", "Destination down: $rm $ru ($du)\n");
}
...
8.2. dispatcher:dst-up
When defined, the module calls event_route[dispatcher:ds-up] when a
destination that was previously down (probing) comes up. A typical use
case is to update NMC equipment as to the status of a destination.
...
event_route[dispatcher:dst-up] {
xlog("L_ERR", "Destination up: $rm $ru\n");
}
...
Chapter 2. Frequently Asked Questions
2.1. Does dispatcher provide a fair distribution?
2.2. Is dispatcher dialog stateful?
2.3. Where can I find more about Kamailio?
2.4. Where can I post a question about this module?
2.5. How can I report a bug?
2.1.
Does dispatcher provide a fair distribution?
The algoritms doing hashing over parts of SIP message don't guarantee a
fair distribution. You should do some measurements to decide what
hashing algorithm fits better in your environment.
Other distribution algorithms such as round robin or call load
dispatching do a fair distribution in terms of delivered calls to
gateways.
2.2.
Is dispatcher dialog stateful?
No. Dispatcher is stateless, although some distribution algorithms are
designed to select same destination for subsequent requests of the same
dialog (e.g., hashing the call-id).
2.3.
Where can I find more about Kamailio?
Take a look at http://www.kamailio.org/.
2.4.
Where can I post a question about this module?
First at all check if your question was already answered on one of our
mailing lists:
* User Mailing List -
http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
* Developer Mailing List -
http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-dev
E-mails regarding any stable version should be sent to
<sr-users@lists.sip-router.org> and e-mail regarding development
versions or GIT snapshots should be send to
<sr-dev@lists.sip-router.org>.
If you want to keep the mail private, send it to
<sr-users@lists.sip-router.org>.
2.5.
How can I report a bug?
Please follow the guidelines provided at:
https://github.com/kamailio/kamailio/issues