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using IPSLA to test IP Multicast - NoConnection/Busy/Timeout

Hi,

I am trying to use IPSLA to generate a test feed between 2 cisco CE routers (hostnames R15 and R7) which are connected over a Layer 3 VPN MPLS network but i am getting some unexpected results with IPSLA yet with an ICMP ping to the multicast address it works ok.

R15#sh ip int brief
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            192.168.15.1    YES NVRAM  up                    up
FastEthernet0/1            172.30.30.137   YES NVRAM  up                    up
Loopback0                  172.30.30.15    YES NVRAM  up                    up

R7#sh ip int brief
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            unassigned      YES NVRAM  administratively down down
FastEthernet0/1            192.168.7.7     YES NVRAM  up                    up
Serial0/0/0:1              172.30.30.122   YES NVRAM  up                    up
Loopback1                  172.30.30.7     YES NVRAM  up                    up
Loopback7                  10.10.7.1       YES manual up                    up

R7 (test receiver) is configured with "ip igmp join-group 228.88.88.88" under its FastEthernet0/1 interface and also set as "ip sla monitor responder".

R7#sh run | inc igmp|sla
ip sla monitor responder
ip igmp join-group 228.88.88.88

R15 (test sender) is configured with an IPSLA UDP echo probe sending traffic to multicast address 228.88.88.88 as follows:

R15#sh run | b ip sla
ip sla 1
udp-echo 228.88.88.88 65500 source-ip 172.30.30.15
timeout 100
frequency 5
ip sla schedule 1 life forever start-time now

The IPSLA probe is reporting "No connection" and no successes:

R15#sh ip sla statistics 1

Round Trip Time (RTT) for       Index 1
        Latest RTT: NoConnection/Busy/Timeout
Latest operation start time: 15:19:44.332 CET Fri Jul 20 2012
Latest operation return code: No connection
Number of successes: 0
Number of failures: 56
Operation time to live: Forever

Yet when testing this with a standard ICMP ping it works ok and the remote router (R7) where the IGMP join is applied responds:

R15#ping 228.88.88.88 source 172.30.30.15

Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 228.88.88.88, timeout is 2 seconds:
Packet sent with a source address of 172.30.30.15

Reply to request 0 from 172.30.30.122, 8 ms
Reply to request 0 from 172.30.30.122, 8 ms

So i am trying to figure out why the IPSLA is failing but the ICMP ping fails......?


When applying debug ip packet & mpacket on R15 (test sender) i see the UDP echos being generated to destination address 228.88.88.88 but for some reason i see the destination UDP port as being 1967 and not 65500 as i had configured in my SLA probe:

Jul 20 13:38:04: IP: s=192.168.15.1 (local), d=228.88.88.88 (FastEthernet0/0), len 80, sending broad/multicast
Jul 20 13:38:04:     UDP src=58867, dst=1967
Jul 20 13:38:04: IP: s=172.30.30.137 (local), d=228.88.88.88 (FastEthernet0/1), len 80, sending broad/multicast
Jul 20 13:38:04:     UDP src=58867, dst=1967
Jul 20 13:38:04: IP: s=172.30.30.15 (local), d=228.88.88.88 (Loopback0), len 80, sending broad/multicast
Jul 20 13:38:04:     UDP src=58867, dst=1967


When applying debug ip packet & mpacket on R7 (test receiver) i do see the multicast packets inbound from R15 which are generated by the IPSLA probe:

R7#
Jul 20 13:27:04.365: IP(0): MAC sa=*HDLC* (Serial0/0/0:1)
Jul 20 13:27:04.365: IP(0): IP tos=0x0, len=80, id=0, ttl=252, prot=17
Jul 20 13:27:04.365: IP(0): s=172.30.30.137 (Serial0/0/0:1) d=228.88.88.88 (FastEthernet0/1) id=0, ttl=252, prot=17, len=80(80), mforward
Jul 20 13:27:04.365: IP(0): MAC sa=*HDLC* (Serial0/0/0:1)
Jul 20 13:27:04.365: IP(0): IP tos=0x0, len=80, id=0, ttl=251, prot=17
Jul 20 13:27:04.365: IP(0): s=172.30.30.15 (Serial0/0/0:1) d=228.88.88.88 (FastEthernet0/1) id=0, ttl=251, prot=17, len=80(80), mforward
Jul 20 13:27:09.369: IP(0): MAC sa=*HDLC* (Serial0/0/0:1)

Periodically on R7 (test receiver) i also see IP socket 65500 as open then shortly after closed which is the port configured in my IPSLA probe on R15 (test sender):

R7#sh ip sockets
Proto    Remote      Port      Local       Port  In Out Stat TTY OutputIF
17   --listen--          172.30.30.7      1985   0   0    1   0
17   --listen--          224.0.1.40        496   0   0   61 194
17 0.0.0.0             0 172.30.30.7      1967   0   0  211   0
17   --listen--          172.30.30.7       123   0   0    1   0

R7#sh ip sockets
Proto    Remote      Port      Local       Port  In Out Stat TTY OutputIF
17   --listen--          172.30.30.7      1985   0   0    1   0
17   --listen--          224.0.1.40        496   0   0   61 194
17 0.0.0.0             0 172.30.30.7      1967   0   0  211   0
17   --listen--          172.30.30.7       123   0   0    1   0
17 0.0.0.0             0 228.88.88.88    65500   0   0   41   0  <<<<


Can anyone give me an idea of why this IPSLA probe may report as No connection?

Thanks

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