Branch office PSTN call routing

[BALAMURUGAN SINGARAM]

Customer had HQ and Branch office with 512 MPLS line, in HQ alone they had E1 trunk, in branch office for calling PSTN the call should travel via MPLS to HQ, and the branch PSTN call terminated in HQ only,   is it a good design or better we need to add ISDN line in branch level to terminate the PSTN call.

[Marwan ALshawi · Accepted solution]

in terms of good design it is not

because this design has imitations as bellow

1- single point of failure, if the MPLS link is down the branch will be not accessible via PSTN and they will lose PSTN access too

2- the MPLS link will be like a bottleneck for this branch because PSTN calls and onnet calls will go over the PSTN link

however if this is due to customer needs/budget then you can do it like this but make sure to mention the recommendations to have local PSTN

HTH

if helpful Rate

[rad_baver · Accepted solution]

Balamurugan:

I agree with marwanshawi regarding the single point of failure and the bottleneck but where I work all the customers have your proposed scenario:

- HQ with a big internet pipe and big E1/SIP trunks and the remotes with main link and backup link. This design is more cost effective as you can negotiate good pricings in HQ buying in bulk.

Regarding bottleneck, try to use a codec like g729 and test RTP header compression if you are concerned.

Rad Baver

[BALAMURUGAN SINGARAM]

Thanks for the reply, branch to branch they are using 512 KBPS with VPN tunnel, g729 codec is used in between HQ and branch, the issuse is voice quality between the branche and HQ, the ping round trip delay is more than 250 MS [ no packet drops ], QOS is applied in switch and CUCM level, could you please light me do we can fine tune more on WAN interface level.

1) do it possible to use header compression on MPLS cloud

2) do it possible to enable "RSVP" in MPLS link.

Could you please light me on how to enable RSVP & Header compression on MPLS link.

[Marwan ALshawi]

in this case you need to speak with your service provider so the can tell you what class of service they support and you can put voice traffic into the priority Queue in your WAN link and into the SP cloud

but this is somthing you pay your service provider for

HTH

[rad_baver]

Balamurugan:

1) I think it is possible. My R&S skills are oxidized but you can have MPLS VPN configured and use frame-relay as a serial encapsulation where you will be able to configure RTP header compression.

2) RSVP over MPLS: yes. But as Marwashawi said, I prefer to work with the LLQ QOS for voice traffic. For that you will need to agree that with your service provider.

Rad Baver

BALAMURUGAN SINGARAM escribió:
Thanks for the reply, branch to branch they are using 512 KBPS with VPN tunnel, g729 codec is used in between HQ and branch, the issuse is voice quality between the branche and HQ, the ping round trip delay is more than 250 MS [ no packet drops ], QOS is applied in switch and CUCM level, could you please light me do we can fine tune more on WAN interface level.
1) do it possible to use header compression on MPLS cloud
2) do it possible to enable "RSVP" in MPLS link.
Could you please light me on how to enable RSVP & Header compression on MPLS link.

[Marwan ALshawi]

see the bellow link i think is it is the best ever document of QoS to understand and configure QoS

http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/VPNQoS.html

HTH