backhaul on MGCP

[pravkuma]

Do anyone knows what is the purpose of configuring backhaul on MGCP..

I understand when MGCP-PRI backhaul interface is configured , q921 will be terminated on the MGCP gateway and q931 signal will be sent to CCM .

But what i don't get is whats the additional advantage we get by configuring PRI-backhaul and why should i bother configuring this ?

Thanks..

[thisisshanky]

With traditional h323 gateways, the gateways need to be intelligent enough to termination call signalling, perform dialplan/routing decisions, perform digit manipulation etc. With MGCP backhaul all these functions mentioned above can be moved to a central agent called call agent in general. Callmanager is the callagent in the Cisco world. This removes the administrative nightmare of configuring translation rules, dial peers etc on a h323 gateway and have it configured at one place (in the call agent). To conclude, there is less overhead on the end gateways if using MGCP as the protocol with backhaul.

HTH

Sankar

PS: please remember to rate posts!

[pravkuma]

Sankar,

Thanks for the response. Your response explains the difference between the MGCP gateway and h323 gateway but doesn't answer my question on the advantage of MGCP backhaul.

I could connect to the PSTN world using T1-PRI terminated on the MGCP gateway without configuring MGCP backhaul and still get all the advantages highlited in your mail.

What i'm looking for is any specific advantage would i get my configuring MGCP backhaul !

Or am i confused with this MGCP backhaul concept completely !!

Thanks

[mchandak]

the advantage of using MGCP Backhaul is that you have CallManager make the routing decisions as MGCP works as a master/slave protocol. You dont have to configure call routing on both Gateway and CM. It only needs to be configured on CM.

Hopefully this clears the doubt.

EDIT: The Primary Advantage is, reduction of Administrative Overhead

[pravkuma]

What if i don't configure MGCP backhaul ,i mean, if a T1-PRI terminating on MGCP gateway configured without backhaul related configs (i.e without isdn bind-l3 command ) even in this scenario Callagent/CM makes the routing decisions right?

[mchandak]

MGCP cannot work as a mater protocol and therefore cannot handle L3 msgs. Backhaul has to be sent to CallManager. MGCP PRI would not funtion without doing a backual to CCM

[jorruiz]

I realize this post is 4 years old, but I was digging for the answer to this exact same question today, and I don't feel like anybody on this post answered it sufficiently.  They kept giving the advantages of MGCP over H.323 gateways, but not the specifics of what PRI Backhauling allows.  What I tracked down was that with PRI backhauling, you are separating the L2 and L3 messages of the PRI, and backhauling can PRESERVE CALLS if a Callmanager fails.  The gateway can reregister to a backup UCM while the call is still in progress because the L2 portion is still up.  So as far as I can tell it's call preservation that is the answer to this question, not centralized administration.  Correct me if I'm wrong.

[Kiran Kumbhar]

MGCP PRI backhaul is a method for transporting complete IP telephony signaling information from an ISDN PRI interface in an MGCP gateway to Cisco Unified Communications Manager using a highly reliable TCP connection.

It Terminates all ISDN PRI Layer 2. It Manages all Layer 3 signalling information to in packets to Cisco Unified Communication Manager through IP tunnel over TCP connection.

One reason i may provide to configure it is In the event of a Cisco Unified Communications Manager switchover, the secondary Cisco Unified Communications Manager server performs the MGCP PRI backhaul functions. During the switchover, all active ISDN PRI calls are preserved, and the affected MGCP gateway is registered with the new Cisco Unified Communications Manager server through a Restart-in-Progress (RSIP) message

[dimidimi]

What MGCP backhaul does is to forward the information/data it receives from the T1/E1 line to the Call Manager, while MGCP or other gateways forward the information but they process the T1/E1 information locally.

Meaning that if you would like to see that same information from analog perspective, without the backhaul you would have to go to the gateway itself and download the logs from there. In other words - that is the only advantadge that I can think of.

I hope this answers this 10 year-old question in a simplified manner.

Cheers,

Dimitar

[Edward3]

When MGCP backhaul interface is configured, Q921 (Layer 2 of ISDN PRI
Circuit) is terminated on the MGCP gateway (endpoint) whereas the Q931 (Layer 3 of
ISDN PRI circuit) signal is sent to CUCM. This reduces the administrative effort of
configuring the call-routing intelligence at one place i.e. in the call agent or CUCM.