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Bad Multicast sound quality

 
 
Faustino Dina
Guest
Posts: n/a
 
      08-30-2004
Hi,

I'm doing some lab testing for multicasting across cisco routers. I have
two 3810 Cisco routers connected back-to-back by using the Aux port at
38400bps speed. Each Ethernet interface is connected to a different LAN
segment. PCs attached to both segments run Windows 2000/XP Phone Dialer. I
have tested three different configurations recommended by Cisco at Multicast
Quick-Start Configuration Guide
(http://www.cisco.com/warp/public/105/48.html): dense mode, sparse mode with
one RP, and auto-RP with one RP. On the three configuration I've got the
same result: The direct IP dialing PC to PC works with good voice quality,
but the quality of the voice tele-conference is too bad. It works, you can
recognize that somebody is talking on the other end of the line, but it is
impossible to recognize what is spoken. It is similar when you hear Internet
music by a very slow connections. I guess I'm losing packets. First I
suspect the 38400bps lik between routers. But it works great when calling
directly, without multicasting.
What can be wrong? Both routers run IOS 12.0. Any idea is welcomed.

Thanks in advance

--
Faustino Dina

The configuration of the routers is like the following:

Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service udp-small-servers
service tcp-small-servers
!
hostname BOTTOM
!
logging buffered 4096 debugging
no logging console
no logging monitor
enable secret ***
enable password ***
!
!
!
!
!
network-clock base-rate 56k
ip subnet-zero
!
ip multicast-routing
ip dvmrp route-limit 20000
!
!
!
process-max-time 200
!
interface Ethernet0
ip address 10.10.10.253 255.255.255.0
no ip directed-broadcast
ip pim sparse-dense-mode
no ip mroute-cache
!
interface Async1
ip address 192.168.10.2 255.255.255.0
ip directed-broadcast
ip pim sparse-dense-mode
encapsulation ppp
async dynamic routing
async mode dedicated
!
interface Switch0
no ip address
no ip directed-broadcast
encapsulation frame-relay
no ip mroute-cache
no fair-queue
!
no ip http server
no ip classless
ip route 0.0.0.0 0.0.0.0 Ethernet0
ip route 10.10.19.0 255.255.255.0 192.168.10.1
ip pim send-rp-announce Ethernet0 scope 16
ip pim send-rp-discovery scope 16
!
logging trap debugging
logging 10.10.10.67
snmp-server engineID local 000000090200003094FB7AF5
snmp-server community BOTTOM RO
!
line con 0
exec-timeout 0 0
transport input none
line aux 0
modem InOut
transport input all
speed 38400
speed 38400
line 2 3
line vty 0 4
password ****
login
!
!
voice-port 1/1
timeouts call-disconnect 0
!
voice-port 1/2
timeouts call-disconnect 0
!
voice-port 1/5
timeouts call-disconnect 0
timing hookflash-out 0
!
voice-port 1/6
timeouts call-disconnect 0
timing hookflash-out 0
!
!
end


 
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MC
Guest
Posts: n/a
 
      08-31-2004
Do not use the AUX port for this type of testing, The AUX port will cause
too many CPU interupts and not sure how will work trying to handle
multicast. Best to use a dedicated controller IO which will not interupt for
each packet of data as the AUX port will do. The AUX port which is an ASYNC
serial interface will gernerate an interupt for each byte of data.

Also you can enable fast switching of multicast packets using the ip
mroute-cache interface configuration command, fast switching of multicast
packets is off by default. This may help with performance.

Interrupts are generated any time a character is output from the console or
auxiliary ports of a router.

UARTs are slow compared to the processing speed of the router, so it is
unlikely, though possible, that console or auxiliary interrupts can cause a
high CPU utilization on the router, unless the router has a large number of
tty lines in use. However when using AUX ports as a dialbackup connection
can be OK I have seen a few circumstances where using the AUX ports
back-to-back like that can casue a lot of CPU overhead and if combined with
not processing the multicast traffic properly may cause problems.

The TTY Background process is a generic process used by all terminal lines
(console, aux, async, and so on). This itself should not cause and
performance problems of the router but since this process has a lower
priority compared to the other processes that need to be scheduled by the
Cisco IOS software may not be processing the packets through the AUX port as
it should.

Best to use an dedicated controller IO interface for this, weather SYNC or
ASYNC, Dedicated controllers do not have the same limitations as the AUX
port.

"Faustino Dina" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi,
>
> I'm doing some lab testing for multicasting across cisco routers. I have
> two 3810 Cisco routers connected back-to-back by using the Aux port at
> 38400bps speed. Each Ethernet interface is connected to a different LAN
> segment. PCs attached to both segments run Windows 2000/XP Phone Dialer. I
> have tested three different configurations recommended by Cisco at

Multicast
> Quick-Start Configuration Guide
> (http://www.cisco.com/warp/public/105/48.html): dense mode, sparse mode

with
> one RP, and auto-RP with one RP. On the three configuration I've got the
> same result: The direct IP dialing PC to PC works with good voice quality,
> but the quality of the voice tele-conference is too bad. It works, you can
> recognize that somebody is talking on the other end of the line, but it is
> impossible to recognize what is spoken. It is similar when you hear

Internet
> music by a very slow connections. I guess I'm losing packets. First I
> suspect the 38400bps lik between routers. But it works great when calling
> directly, without multicasting.
> What can be wrong? Both routers run IOS 12.0. Any idea is welcomed.
>
> Thanks in advance
>
> --
> Faustino Dina
>
> The configuration of the routers is like the following:
>
> Current configuration:
> !
> version 12.0
> service timestamps debug uptime
> service timestamps log uptime
> no service password-encryption
> service udp-small-servers
> service tcp-small-servers
> !
> hostname BOTTOM
> !
> logging buffered 4096 debugging
> no logging console
> no logging monitor
> enable secret ***
> enable password ***
> !
> !
> !
> !
> !
> network-clock base-rate 56k
> ip subnet-zero
> !
> ip multicast-routing
> ip dvmrp route-limit 20000
> !
> !
> !
> process-max-time 200
> !
> interface Ethernet0
> ip address 10.10.10.253 255.255.255.0
> no ip directed-broadcast
> ip pim sparse-dense-mode
> no ip mroute-cache
> !
> interface Async1
> ip address 192.168.10.2 255.255.255.0
> ip directed-broadcast
> ip pim sparse-dense-mode
> encapsulation ppp
> async dynamic routing
> async mode dedicated
> !
> interface Switch0
> no ip address
> no ip directed-broadcast
> encapsulation frame-relay
> no ip mroute-cache
> no fair-queue
> !
> no ip http server
> no ip classless
> ip route 0.0.0.0 0.0.0.0 Ethernet0
> ip route 10.10.19.0 255.255.255.0 192.168.10.1
> ip pim send-rp-announce Ethernet0 scope 16
> ip pim send-rp-discovery scope 16
> !
> logging trap debugging
> logging 10.10.10.67
> snmp-server engineID local 000000090200003094FB7AF5
> snmp-server community BOTTOM RO
> !
> line con 0
> exec-timeout 0 0
> transport input none
> line aux 0
> modem InOut
> transport input all
> speed 38400
> speed 38400
> line 2 3
> line vty 0 4
> password ****
> login
> !
> !
> voice-port 1/1
> timeouts call-disconnect 0
> !
> voice-port 1/2
> timeouts call-disconnect 0
> !
> voice-port 1/5
> timeouts call-disconnect 0
> timing hookflash-out 0
> !
> voice-port 1/6
> timeouts call-disconnect 0
> timing hookflash-out 0
> !
> !
> end
>
>



 
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