[SR-Users] Dispatcher and round-robin ignoring priorities?

[Daniel-Constantin Mierla]

Hello,

priority is used to sort the destination addresses list at startup (at 
load time). It has impact on which will be the first time used address 
in round-robin selection.

You should be able to achieve what you want by chaining dispatching over 
two groups of addresses, first round-robin over the group with 'higher 
priority from your point of view', then do to the second if none from 
first group routes it.

Cheers,
Daniel

On 3/19/12 2:23 PM, Øyvind Kolbu wrote:
> Our PSTN provider has three servers. Two of them are located in our town,
> and we prefer them, and the last one much further away. We can use them
> interchangeably.
>
>  From our dispatcher file:
>
>      # 10: PSTN
>      10 sip:preferred1.example.com:7476 0 5
>      10 sip:preferred2.example.com:7476 0 5
>      10 sip:third.example.com:7476 0 4
>
> In our dispatch router we use 'ds_select_dst("10","4")'. Then the
> round-robin algorithm evenly distributes the load on all three of them,
> instead of round robin on the ones with priority 5 and fallbacking to
> priority 4. Is the unconditional round robin as excepted?
>
> When changing the selection algorithm to "8", «use first destination», the
> dispatcher module correctly uses first "preferred2", then "preferred1" and
> then lastly "third".
>
> Why «first destination» is not the first one listed in the dispatcher file
> has always puzzled me..
>
> # kamailio -V
> version: kamailio 3.2.1 (i386/linux) 31c991
> flags: STATS: Off, USE_IPV6, USE_TCP, USE_TLS, TLS_HOOKS, USE_RAW_SOCKS,
> DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC,
> DBG_QM_MALLOC, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE,
> USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES
> ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16,
> MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 4MB
> poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.
> id: 31c991
> compiled on 08:08:06 Dec  6 2011 with gcc 4.1.2
>

-- 
Daniel-Constantin Mierla
Kamailio Advanced Training, April 23-26, 2012, Berlin, Germany
http://www.asipto.com/index.php/kamailio-advanced-training/