Acme Packet SBC “SIP Monitoring and Trace” Configuration21 Jul 2013
Diagnosing a troubled
SIP call has a tendency to be a real pain. Whether it’s running
tcpdump, or collecting
debugs, having to sort through duplicate packets and attempting to merge different pcap files together does not provide a simple way to troubleshoot a single call while looking at both sides of the call in a single ladder diagram.
Fortunately the Acme Packet SBC now includes a free tool embedded in the code that once enabled, allows it turns the SBC into a
SIP capture device. The distinct advantage here is seeing
both sides of a call in a
single ladder diagram. Even better, extra (and very useful) information is included in between each step of the ladder diagram referencing internal “logic decisions” as they occur as traffic passes through the SBC. Finding a particular capture is easy using
Search Filters which allow you to specify just about any criteria.
Pop-up context provides tool tips and additional information about a call depending on what area you are hovering over. It is also possible to export a capture locally so it may be emailed and viewed by others rather than having a variety of users logging into the SBC’s web interface. Alternatively,
captures may be exported as ASCII text files with proper and readable formatting of the call information.
---Session Summary--- Startup Time: 2012-04-26 08:40:44.624 State: TERMINATED-200 Duration: 9 From URI: sipp <:sip:firstname.lastname@example.org:5060>;tag=25 To URI: sut <sip:email@example.com:5060>;tag=3453 Ingress Src Address: 172.16.34.10 Ingress Src Port: 5060 Ingress Dest Address: 172.16.34.226 Ingress Dest Port: 5060 Egress Source Address: 192.168.34.226 Egress Source Port: 5060 Egress Destination Address: 192.168.34.17 Egress Destination Port: 5060 Ingress Realm: Access Egress Realm: Core Ingress NetworkIf: s0p0 Egress NetworkIf: s1p0
There are three main parts to viewing a captured call. The first is the
Session Summary view which contains information such as source and destination IP addresses, URI’s, Realms, etc..
The second viewing pane is
SIP Message Details. This is the actual
ladder diagram and SBC events.
The third pane is for viewing
QoS statistics such as jitter, packet loss, delay, and MOS scores for the specified call.
In order to enable web browser viewing of SIP Monitoring and Trace the web server must be set to the
web-server-config state enabled inactivity-timeout 5 http-state enabled http-port 80 https-state enabled https-port 443 tls-profile
The next step is to create one or more
filters. In the following example there is a filter called hostedIpPbx and in the user portion of the filter any SIP messages containing the phone number digits 781801 will be captured.
sbc# config t sbc(configure)# session-router sbc(session-router)# filter-config sbc(filter-config)# select name: 1. Broadsoft 2. Cisco 3. Genesys selection: 1 sbc#(filter-config)# show name Broadsoft address 0.0.0.0 user 781801 <- Phone prefix NPA-NXX to capture
The next step is to enable sip-monitoring and identify which
monitoring filter should be used. Applying the filter here enabled the filter globally on the system. Usually filters are best applied to specific realms or session agents (under monitoring-filters) to capture only interesting traffic.
sbc(sip-minitoring)# show sip-monitoring state enabled monitoring-filters Broadsoft trigger-window 0
In this particular network there are IP phones behind a Cisco ASA firewall which NAT to the public internet and need to register to a BroadWorks SIP softswitch which is being “hidden” behind the SBC.
Below is the capture based on the filter above. Note the phone number starts with