On Tue, 08 Jul 2008 20:47:24 +0100, Jono wrote:
> On each building is a Motorola "Square-ial" supplying a microwave link
> for the two sites' single LAN.
>
> Q1. Is this likely to be a duplex link?
'iperf' will tell you. Run a duplex test [-d] then a tradeoff test [-r]
and if there's a massive difference between the two, then it's probably
not full duplex.
Also, running it in UDP mode will tell you the jitter and loss for the
bandwidth and packet size you give it. For example on my switched fast
ethernet LAN, I started iperf in UDP server mode with a packet length of
160 bytes, roughly what you'd see with SIP in G.711:
hostA# iperf -s -u -l 160
Then on another machine, UDP mode, 100kbps, 160 byte packets, for 60
seconds:
hostB# iperf -u -c hostA -b 100k -d -l 160 -t 60
Client connecting to 192.168.1.28, UDP port 5001
Sending 160 byte datagrams
UDP buffer size: 120 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.1.3 port 51712 connected with 192.168.1.28 port 5001
[ 4] local 192.168.1.3 port 5001 connected with 192.168.1.28 port 34038
[ 3] 0.0-60.0 sec 733 KBytes 100 Kbits/sec
[ 3] Sent 4689 datagrams
[ 4] 0.0-60.0 sec 733 KBytes 100 Kbits/sec 0.003 ms 0/ 4689 (0%)
[ 3] Server Report:
[ 3] 0.0-60.0 sec 733 KBytes 100 Kbits/sec 0.002 ms 0/ 4689 (0%)
So jitter and packet loss are almost non-existent, and as a result VoIP
is excellent. Wirelessly:
Client connecting to 192.168.1.33, UDP port 5001
Sending 160 byte datagrams
UDP buffer size: 120 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.1.3 port 50076 connected with 192.168.1.33 port 5001
[ 4] local 192.168.1.3 port 5001 connected with 192.168.1.33 port 54587
[ 3] 0.0-60.0 sec 733 KBytes 100 Kbits/sec
[ 3] Sent 4689 datagrams
[ 4] 0.0-60.0 sec 733 KBytes 100 Kbits/sec 1.573 ms 0/ 4689 (0%)
[ 3] Server Report:
[ 3] 0.0-60.0 sec 732 KBytes 99.9 Kbits/sec 1.406 ms 4/ 4689
(0.085%)
A bit of packet loss and much more jitter, but VoIP is still spotless.
Finally, over a DSL-DSL VPN:
------------------------------------------------------------
Client connecting to 192.168.253.9, UDP port 5001
Sending 160 byte datagrams
UDP buffer size: 120 KByte (default)
------------------------------------------------------------
[ 4] local 172.29.25.1 port 58212 connected with 192.168.253.9 port 5001
[ 3] local 172.29.25.1 port 5001 connected with 192.168.253.9 port 59885
[ 4] 0.0-60.0 sec 733 KBytes 100 Kbits/sec
[ 4] Sent 4689 datagrams
[ 3] 0.0-60.0 sec 733 KBytes 100 Kbits/sec 0.950 ms 0/ 4689 (0%)
[ 4] Server Report:
[ 4] 0.0-60.0 sec 733 KBytes 100 Kbits/sec 0.847 ms 0/ 4689 (0%)
So over the WAN looks better than wirelessly.
> Q2. If Q1 is yes, anyone got any suggestions for getting a phone
> connected in site 2 to site 1's analogue PBX?
Even if it's not full duplex, then for light use it should be OK.
> Can Grandstreams be connected back-to-back like the SPAs?
Anything that will let you dial by IP [and let you put that number on a
speed dial or sofkey] without registration will do.
--
<http://ale.cx/> (AIM:troffasky) ()
23:01:02 up 7 days, 9:28, 3 users, load average: 0.25, 0.12, 0.10
Convergence, n: The act of using separate DSL circuits for voice and data
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