SRST configuration for Jabber

[mm322]

Hello everyone,

trying to set up SRST for Jabber with ISR 4331 routers, but haven't managed so far to find documents where this is explained in details.

Some information was found here below, but except for some posts on the Community seems that no configuration example was found.

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cusrst/admin/sccp_sip_srst/configuration/guide/SCCP_and_SIP_SRST_Admin_Guide/srst_roadmap.html#qtm_lvm_p4b

Any suggestion on this?

Thanks

MM

[Roger Kallberg · Accepted solution]

It is AFAIK just the SIP SRST configuration that is needed for this. The below is from our in-house configuration template for voice gateways.

SIP SRST configuration

voice service voip
 allow-connections sip to sip
 sip
  registrar server
!
voice register global
 default mode
 system message SRST Failover
 max-dn 256 ;max-dn should be set to double amount of max-pool
 max-pool 128 ;set max-pool to the maximum that router model can support
 timezone 41
 phone-mode phone-only
!
voice register pool 1
 id network x.x.x.x mask y.y.y.y	;x.x.x.x,/y.y.y.y refer to network range assigned to entire site, not just the voice vlan
 translation-profile incoming SRST-IN
 dtmf-relay rtp-nte
 voice-class codec 1
 no vad
!
sip-ua
 registrar ipv4:[A.A.A.A] expires 3600

/**
[A.A.A.A] = LAN Interface IP Address (Voice Vlan)  

[Maren Mahoney]

The command "phone-mode phone-only" under voice register global is the one most folks miss when configuring SRST to support Jabber. -- Maren

[mm322]

Many thanks Roger and Maren,

I am awaiting this to be tested with the help of the customer (who is in charge with acls on their router).

Do you think SRST may be tested by using a Jabber for Windows (CSF) + editing the Windows file hosts in a way that CUCM nodes are no more reachable by the pc? Too simplistic idea?

[Roger Kallberg]

The simplest way I found to test SRST is to setup host routes in the L3 device that connects the site to the WAN to point all traffic destined to CMs to dev null. For instance this ip route <IP of CM> 255.255.255.255 Null0. This will block all traffic destined to CM and effectively put the devices into SRST mode.

[mm322]

Absolutely agreed Roger, unfortunately this is something out of my control and while am awaiting (for ever) the customer to be available on this, I would like to have already a sip device to test SRST.

Windows file hosts appears to be a possible easy trick, not sure though if it is going to work as it depends on Jabber mechanisms (which I don't know in deep details and may be a bit more complex).

[mm322]

In case ever useful to anyone: result of this particular testing is that Windows file hosts does not appear a workable option (Jabber will unregister from CUCM but won't register on the ISR).

Got Jabber successfully registered on SRST by properly setting Windows Firewall on the pc (i.e. blocking all applications - not only Jabber - from and to CUCM nodes).

[Maren Mahoney]

Thank you for sharing that! It really helps folks to run across this later. -- Maren

[Roger Kallberg]

Just a comment. It’s not very friendly to mark your own response as the solution to your question. That’s a sure way of not getting further attention from peers in the community.

[mm322]

I have removed the 'solution' label from my comment, my original intention was actually to highlight the potentially helpful comments to this post which IMHO would be: yours, Roger and Maren, about how the configuration should be on the ISR + mine about how easily testing SRST SIP with Jabber if you have no better way to get this done.

[Roger Kallberg]

It's fine to mark your own post as the solution as long as you also mark other posts as solution from those that you got help from.