IOS SIP-Options Ping

[Oswaldo Torres]

The Out-of-dialog (OOD) Options Ping feature provides a keepalive mechanism at the SIP level between any number of destinations. A generic heartbeat mechanism allows Cisco Unified Border Element to monitor the status of SIP servers or endpoints and provide the option of busying-out a dial-peer upon total heartbeat failure. When a monitored endpoint heartbeat fails, the dial-peer is busied out.

I have this configuration in my Router

dial-peer voice 5002 voip
 description DIAL-PEER DE SALIDA HACIA SONUS
 destination-pattern 00.T
 session protocol sipv2
 session target ipv4:172.25.1.233
 session transport udp
 voice-class sip early-offer forced
 voice-class sip options-keepalive up-interval 20 down-interval 40 retry 6
 voice-class sip bind control source-interface Loopback0
 voice-class sip bind media source-interface Loopback0
 dtmf-relay rtp-nte
 codec g711alaw
 no vad
!

I have this version

C2900 Software (C2900-UNIVERSALK9-M), Version 15.4(3)M1

As you can see in this figure

The Router send a SIP-Option every 20 seconds (up-interval = 20).

This is a operational behavior.

What happen, when the remote peer is unreacheable...

After the packets No. 257 and 258, I apply an ACL to block the communications between 177.1.254.1 and 172.25.1.233.

As you can see, the interval between the packets No. 257 and 759 are 20 seconds (up interval), but after this we have 6 attempts (retry =6) to reach the IP 172.25.1.233.

When the router attempt six times (retry =6 )and we don't have response. On the router we have the following:

R_ISOL_HQ_7.06_36#
Jun 19 20:30:08.820: %SIP-5-DIALPEER_STATUS: VoIP dial-Peer <5002> is Busied out
R_ISOL_HQ_7.06_36#
R_ISOL_HQ_7.06_36#sh dial-peer voice sum
dial-peer hunt 0
             AD                                    PRE PASS                OUT
TAG    TYPE  MIN  OPER PREFIX    DEST-PATTERN      FER THRU SESS-TARGET    STAT PORT    KEEPALIVE
5001   voip  up   up                                0  syst                     
5002   voip  up   up             00.T               0  syst ipv4:172.25.1.233             busyout   
5003   voip  up   up             00.T               0  syst ipv4:172.25.101.233           active    
6001   voip  up   up             6....              0  syst ipv4:177.56.25.10   
6002   voip  up   up                                0  syst ipv4:172.25.1.233   
R_ISOL_HQ_7.06_36#

As you can see the dial-peer is busyout.

Meanwhile the peer is not reachable, we have the next

The Router send a SIP-Option every 40 seconds (down-interval = 40).

What happen, when the remote peer is back reachable...

After the packet No. 934, I remove the ACL that block the communications between 177.1.254.1 and 172.25.1.233.

As you can see, the interval between the packets No. 24539 and 25779 are aprox. 40 seconds (down interval), but after this we have 6 attempts (retry 6) (25848 to 26939) to reach the IP 172.25.1.233, and all of this attempts have a response.

After the packet 26939, on the router we have the following:

R_ISOL_HQ_7.06_36#
Jun 19 20:45:55.388: %SIP-5-DIALPEER_STATUS: VoIP dial-Peer <5002> is Up
R_ISOL_HQ_7.06_36#
R_ISOL_HQ_7.06_36#sh dial-peer voice sum
dial-peer hunt 0
             AD                                    PRE PASS                OUT
TAG    TYPE  MIN  OPER PREFIX    DEST-PATTERN      FER THRU SESS-TARGET    STAT PORT    KEEPALIVE
5001   voip  up   up                                0  syst                     
5002   voip  up   up             00.T               0  syst ipv4:172.25.1.233             active    
5003   voip  up   up             00.T               0  syst ipv4:172.25.101.233           active    
6001   voip  up   up             6....              0  syst ipv4:177.56.25.10   
6002   voip  up   up                                0  syst ipv4:172.25.1.233   
R_ISOL_HQ_7.06_36#

As you can see the dial-peer is active.

[indian567]

I'd like just to add that the router waits 500ms for a response. So even though the response comes, but if it's late, the dial-peer is busied-out. This timer can be modified by:

conf t

sip-ua

timers options xxx

[Benjamin Krueger]

Thanks Oswaldo for your post.

I have a question about dial-peer and option ping or maybe I will try understand some mechanics.

The setting is a little bit different then yours:

What happened when we have only one dial-peer with following router setup (the other configuration should be similar to your configuration):

...
voice class server-group 1
ipv4 192.168.0.2 preference 1
ipv4 192.168.0.3 preference 2
ipv4 172.16.0.2 preference 3
…
dial-peer voice 5002 voip
session server-group 1
voice-class sip options-keepalive up-interval 20 down-interval 40 retry 6
…
So dial-peer 5002 voip is like I said the only dial-peer for voip traffic. Did the OOD options ping also working? Did the router notice that preference 1 (192.168.0.2) for example is not available and try directly to contact preference 2? Or would it not working, because he had multiple options for that dial-peer and would never “shut down” one of the participants?

Best regards
Benjamin

[HARIS_HUSSAIN]

In the documentation i can see below behavior for DNS with Multiple Addresses.

 If a SIP server is configured as a DNS hostname, OOD Options pings are sent to all the returned addresses until a response is received.

But the Pre-requistes for OOD to work is specified as below

The following are required for OOD Options ping to function. If any are missing, the Out-of-dialog (OOD) Options ping will not be sent and the dial peer is reset to the default active state.

–Dial-peer should be in active state

–Session protocol must be configured for SIP

–Configure Session target or outbound proxy must be configured. If both are configured, outbound proxy has preference over session target.

http://www.cisco.com/c/en/us/td/docs/ios/voice/cube/configuration/guide/vb_book/vb_book/vb_9321.html

So Based on above criteria it seems that OOD is not supported with session group command !! 

Still Need to confirm the same via field test on Voice Router!!

Thanks

Haris

[Benjamin Krueger]

Hello Haris!

I think your correct, that the old keep alive function for a single dial-peer is not supported and working, but a new function with server-group and keepalive group  will support my issue or question.

Destination Server Group (From 15.4(1)T onwards)

...The destinations of a server-group are then used for outgoing call setup when a SIP dial-peer with server-group is selected as an outbound dial-peer.
New OOD Options Ping Keepalive Group supports a SIP dial-peer with a server group as a session target. Separate Options Ping Keepalive connections are established on each remote target of a server group. A dial-peer is put to BUSYOUT state if all Option Ping keepalive connections of a server group are timeout.
Server group is not supported by OOD Options Keepalive (with separate OOD Options Keepalive connection on per dial-peer) method.

You can find complete guide and syntax under the following link: 
http://www.cisco.com/c/en/us/support/docs/voice/dial-plan/200103-Configure-and-Troubleshoot-Multiple-Patt.html#anc29

Best regards
Ben