Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

VPN MPLS overhead

Hi,

I have two questions:

a) Anybody know how can I calculate the overhead in VPN MPLS network ?

b) And about Voice over VPN MPLS, how much Kbps need I reserve to each voice channel ?

TIA

1 ACCEPTED SOLUTION

Accepted Solutions

Re: VPN MPLS overhead

Hi,

there is a minimum of two MPLS labels (i.e. 8 Bytes) per VPN IP packet in most cases.

To calculate the VoIP bandwidth per call you need to account for the additional 8 Bytes. F.e. Voice with G.729(a) 8 kbps voice data, 20 ms (=Bytes) per packet

PPP on the link (8 Bytes L2 overhead), 48 Bytes of overhead for MPLS and L3/4 (2 MPLS labels + IP/UDP/RTP):

76 Byte per voip packet, 50 packets per second

gives you 30.4 kbps per call.

A different L2 encapsulation results in different bandwidth requirements.

Regards, Martin

1 REPLY

Re: VPN MPLS overhead

Hi,

there is a minimum of two MPLS labels (i.e. 8 Bytes) per VPN IP packet in most cases.

To calculate the VoIP bandwidth per call you need to account for the additional 8 Bytes. F.e. Voice with G.729(a) 8 kbps voice data, 20 ms (=Bytes) per packet

PPP on the link (8 Bytes L2 overhead), 48 Bytes of overhead for MPLS and L3/4 (2 MPLS labels + IP/UDP/RTP):

76 Byte per voip packet, 50 packets per second

gives you 30.4 kbps per call.

A different L2 encapsulation results in different bandwidth requirements.

Regards, Martin

1249
Views
0
Helpful
1
Replies