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Acme Packet Media (RTP) Troubleshooting

Who loves troubleshooting media issues? Not me. While some issues require a full packet capture, you can find out a number of things from a simple command. Like when you realize put a steering-pool in the wrong vlan…

I find myself using ‘show nat by-addr ‘ frequently. You do need to know the IP from the SDP c=line. A call must also be active when troubleshooting.

Basically this command gives you the VLAN info on the East / West sides from the call. It also provides the port used by the SDP (you can match this with your INVITE / 200OK ). It also displays the init_flow_guard, which in a normal scenario should be 4294967295.

The init_flow_guard is a timer that is set when the SBC receives a final 200OK of an INVITE transaction. If no media is sent, the timer begins to count down. As soon as the NAT table receives a single RTP packet, the ifg changes to 4294967295.

As always, mess around with it on your lab. See what you can discover on your network.
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sd1.# show nat by-addr 10.1.1.1

———————————
NAT table search address 801 :
Flow type: Fully qualified flow. Weight = 31
SA_flow_key : 10.1.1.1 SA_prefix : 32
DA_flow_key : 172.1.1.1 DA_prefix : 32
SP_flow_key : 0 SP_prefix : 0
DP_flow_key : 21136 DP_prefix : 15
VLAN_flow_key : 252
Protocol_flow_key : 17
Ingress_flow_key : 0
Ingress Slot : 0
Ingress Port : 0
NAT IP Flow Type : IPv4 to IPv4
XSA_data_entry : 72.X.X.X
XDA_data_entry : 216.X.X.X
XSP_data_entry : 24194
XDP_data_entry : 24120

Egress_data_entry : 1
Egress Slot : 1
Egress Port : 0
flow_action : 0X41
optional_data : 0
FPGA_handle : 0x00000000
assoc_FPGA_handle : 0x00000000
VLAN_data_entry : 193
host_table_index : 801
Switch ID : 0x00000002
average-rate : 0
weight : 0x1f
init_flow_guard : 4294967295
inact_flow_guard : 2
max_flow_guard : 86397
payload_type_2833 : 0
index_2833 : 0
pt_2833_egress : 0
qos_vq_enabled : 11
codec_type : 578155832
Call Recorder : 31304, Egress, Signal
HMU_handle : 578155832
sd1.ord1#