ATM QoS only works in upload direction and there are several types:
-UBR: Unspecified Bit Rate.
-VBR: Variable Bit Rate.
-CBR: Constant Bit Rate.
And the priority is CBR>VBR>UBR.
Different ATM QoS types need different parameters.
CBR/UBR services only can map to PCR parameters.
VBR services use PCR, SCR and MBS parameters.
The used parameters are as follows:
-PCR, Peak Cell Rate: maximum cell transfer rate.
-SCR, Sustainable Cell Rate: average allowable, long-term cell transfer rate.
-MBS, Maximum Burst Size: the cell numbers will be sent per second.
Take using Vigor2820 in triple-play service environment for example:
-PVC1 : INTERNET –>UBR, Internet service is not so sensitive, we can use UBR.
-PVC3: VOIP —> CBR, PCR=744, VoIP service is most sensitive, we can use CBR.
PCR 744 means 744 cells which is equal to 744*8*48/1024=279 kbits
1 cell = 53 bytes = (5+48) bytes ( header had 5 bytes)
-PVC4 : TR069 –> UBR, Management service is not so sensitive, we can use UBR.
-PVC5: VIDEO —> rt-VBR, PCR=744, SCR=372, MBS=1000, IPTV service is also sensitive but it is not usually in use, we can use VBR.
PCR 744 cells (744*8*48/1024) is equal to 279 kbits.
SCR 372 cells (372*8*48/1024) is equal to 139.5kbits.
PCR should > SCR.
Please follow the steps below to do the configurations.
1.Go to WAN>Multi-PVCs page.
2.1 Select PVC3 then configure VoIP service to use CBR.
2.2 The VoIP service here means the VoIP service of Vigor itself.
You can specify which SIP account to go via which Interface via VoIP>SIP accounts.
In this example, the SIP should go through PVC.
Note: if you have additional VoIP device (not the VoIP service Vigor provides) and want it to go through PVC to ISP, please create another PVC and map one LAN port to the PVC.
To configure PVC and LAN Port mapping, please refer to step 4.
2.3 Select ATM QoS tab then configure PCR to 744.
3. Select PVC4 then configure Management service to use UBR.
4.1 Configure PVC6 to use rtVBR in General page and map it to port 4 in Port-based Bridge page.
Then port 4 will be in bridge mode after the configuration and it can use to connect to a set top box/media client.
4.2 Select ATM QoS tab then configure PCR to 744, SCR to 372 and MBS to 1000.