From: Guoxing Jiang (jianggx@xxxxxxxxxxxxxxxxxxx)
Date: Sat Oct 28 2000 - 04:03:01 GMT-3
Hello,
I just borrowed two 1750-4Vs, and did some pratices according the
examples that found in CCO. But I met some puzzled things when I did
the example--VoIP with PPP over Low Bandwidth leased Line and RTP Priority
(http://www.cisco.com/warp/customer/793/voip/voip_ppp_lowbw_rtp_prio.html).
First I set the clock rate at 64000. everthing seems ok. But when I
lowered the clock rate to 28800. the voice became worse,jetter,
something lost. But if I don't using multilink(remove the serial
interface from the multilink interface), the voice is ok and
acceptable. Later I found every frame be splited into 40 bytes long
packets when using multilink. Maybe it make the voice worse, so I add
"no ppp multilink fragmentation" under the multilink interface. It is
ok, but if I need to add this command, what's the aim of using
multilink ppp with interleaving?? I think the fragmentation is the
core of "multilink with interleave", am I right?
I want to control the split packet size, but I can't find how to change
the default 40 bytes length.
Another strange things, when I using multilink, if I using extended
ping and set the packet size above 500, it am always failed. but it is
ok, if the packet size less than 500. why?????
Final question, can I simulated payload using long ping when the call
is active? It's really affected the voice quality, and I tried to
config RSVP and the multiling with interleaving, just like I said
above, it didn't resolve the problem, maybe more worse.
My equipments is two 1750-4v, two 2 vic-2fxs, three phones.
my configuration:
r7#show running-config
Building configuration...
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname r7
!
!
memory-size iomem 25
ip subnet-zero
no ip domain-lookup
!
!
voice-port 2/0
!
voice-port 2/1
!
dial-peer voice 1 voip
destination-pattern 888..
dtmf-relay cisco-rtp
ip precedence 5
session target ipv4:8.8.8.8
!
dial-peer voice 2 pots
destination-pattern 77701
port 2/0
!
process-max-time 200
!
interface Loopback1
ip address 7.7.7.7 255.255.255.0
no ip directed-broadcast
!
interface Multilink1
ip unnumbered Loopback1
no ip directed-broadcast
ip rtp priority 16384 16383 24
ip rtp header-compression iphc-format
ip tcp header-compression iphc-format
no ip mroute-cache
fair-queue 64 16 0
no cdp enable
ppp multilink
ppp multilink fragment-delay 10
ppp multilink interleave
multilink-group 1
!
interface Serial0
bandwidth 28
no ip address
no ip directed-broadcast
encapsulation ppp
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
!
interface FastEthernet0
no ip address
no ip directed-broadcast
shutdown
!
ip classless
no ip http server
!
!
line con 0
transport input none
line aux 0
line vty 0 4
login
!
!
end
r7#
r8#show run
Building configuration...
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname r8
!
!
memory-size iomem 25
ip subnet-zero
no ip domain-lookup
!
voice-port 2/0
!
voice-port 2/1
!
dial-peer voice 1 voip
destination-pattern 777..
dtmf-relay cisco-rtp
ip precedence 5
session target ipv4:7.7.7.7
!
dial-peer voice 2 pots
destination-pattern 88801
port 2/0
!
dial-peer voice 3 pots
destination-pattern 88802
port 2/1
!
process-max-time 200
!
interface Loopback1
ip address 8.8.8.8 255.255.255.0
no ip directed-broadcast
!
interface Multilink1
ip unnumbered Loopback1
no ip directed-broadcast
ip rtp priority 16384 16383 24
ip rtp header-compression iphc-format
ip tcp header-compression iphc-format
no ip mroute-cache
fair-queue 64 16 0
no cdp enable
ppp multilink
ppp multilink fragment-delay 10
ppp multilink interleave
multilink-group 1
!
interface Serial0
bandwidth 28
no ip address
no ip directed-broadcast
encapsulation ppp
no fair-queue
clockrate 28800
ppp multilink
multilink-group 1
!
interface FastEthernet0
no ip address
no ip directed-broadcast
shutdown
!
ip classless
no ip http server
!
!
line con 0
transport input none
line aux 0
line vty 0 4
login
!
!
end
r8#
r8#ping
Protocol [ip]:
Target IP address: 7.7.7.7
Repeat count [5]:
Datagram size [100]: 500
Timeout in seconds [2]:
Extended commands [n]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 500-byte ICMP Echos to 7.7.7.7, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 176/179/180 ms
r8#
r8#ping
Protocol [ip]:
Target IP address: 7.7.7.7
Repeat count [5]:
Datagram size [100]: 600
Timeout in seconds [2]: 4
Extended commands [n]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 600-byte ICMP Echos to 7.7.7.7, timeout is 4 seconds:
.....
Success rate is 0 percent (0/5)
r8#
Best regards,
Guoxing Jiang mailto:jianggx@transcentury.com.cn
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