Difference between revisions of "Bandwidth estimates"
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| + | == Packet overhead == | ||
| + | Communication over an IP-network has some overhead for each data-packet. | ||
| + | |||
| + | |||
| + | |||
| + | |||
| + | '''TCP over Ethernet:''' | ||
| + | * Assuming no header compression (e.g. not PPP) | ||
| + | * Add 20 Bytes IPv4 header or 40 Bytes IPv6 header (no options) | ||
| + | * Add 20 Bytes TCP header | ||
| + | * Add 12 Bytes optional TCP timestamps | ||
| + | * Max TCP Payload data rates over ethernet are thus: | ||
| + | ** (1500-'''40''')/(38+1500) = 94.9285 % IPv4, minimal headers | ||
| + | ** (1500-'''52''')/(38+1500) = 94.1482 % IPv4, TCP timestamps | ||
| + | ** (1500-'''52''')/(42+1500) = 93.9040 % 802.1q, IPv4, TCP timestamps | ||
| + | ** (1500-'''60''')/(38+1500) = 93.6281 % IPv6, minimal headers | ||
| + | ** (1500-'''72''')/(38+1500) = 92.8479 % IPv6, TCP timestamps | ||
| + | ** (1500-'''72''')/(42+1500) = 92.6070 % 802.1q, IPv6, ICP timestamps | ||
| + | |||
| + | '''UDP over Ethernet:''' | ||
| + | * Add 20 Bytes IPv4 header or 40 Bytes IPv6 header (no options) | ||
| + | * Add 8 Bytes UDP header | ||
| + | * Max UDP Payload data rates over ethernet are thus: | ||
| + | ** (1500-28)/(38+1500) = 95.7087 % IPv4 | ||
| + | ** (1500-28)/(42+1500) = 95.4604 % 802.1q, IPv4 | ||
| + | ** (1500-48)/(38+1500) = 94.4083 % IPv6 | ||
| + | ** (1500-48)/(42+1500) = 94.1634 % 802.1q, IPv6 | ||
| + | |||
| + | |||
| + | ([http://sd.wareonearth.com/~phil/net/overhead/ Source]) | ||
| + | |||
| + | |||
== Audio codecs == | == Audio codecs == | ||
Bandwidth Requirements for Several Common VoIP Compression Algorithms | Bandwidth Requirements for Several Common VoIP Compression Algorithms | ||
Revision as of 21:57, 30 January 2007
Packet overhead
Communication over an IP-network has some overhead for each data-packet.
TCP over Ethernet:
- Assuming no header compression (e.g. not PPP)
- Add 20 Bytes IPv4 header or 40 Bytes IPv6 header (no options)
- Add 20 Bytes TCP header
- Add 12 Bytes optional TCP timestamps
- Max TCP Payload data rates over ethernet are thus:
- (1500-40)/(38+1500) = 94.9285 % IPv4, minimal headers
- (1500-52)/(38+1500) = 94.1482 % IPv4, TCP timestamps
- (1500-52)/(42+1500) = 93.9040 % 802.1q, IPv4, TCP timestamps
- (1500-60)/(38+1500) = 93.6281 % IPv6, minimal headers
- (1500-72)/(38+1500) = 92.8479 % IPv6, TCP timestamps
- (1500-72)/(42+1500) = 92.6070 % 802.1q, IPv6, ICP timestamps
UDP over Ethernet:
- Add 20 Bytes IPv4 header or 40 Bytes IPv6 header (no options)
- Add 8 Bytes UDP header
- Max UDP Payload data rates over ethernet are thus:
- (1500-28)/(38+1500) = 95.7087 % IPv4
- (1500-28)/(42+1500) = 95.4604 % 802.1q, IPv4
- (1500-48)/(38+1500) = 94.4083 % IPv6
- (1500-48)/(42+1500) = 94.1634 % 802.1q, IPv6
(Source)
Audio codecs
Bandwidth Requirements for Several Common VoIP Compression Algorithms
| Codec | Bit rate | NEB |
|---|---|---|
| G.711 | 64 Kbps | 87.2 Kbps |
| G.729 | 8 Kbps | 31.2 Kbps |
| G.723.1 | 6.4 Kbps | 21.9 Kbps |
| G.723.1 | 5.3 Kbps | 20.8 Kbps |
| G.726 | 32 Kbps | 55.2 Kbps |
| G.726 | 24 Kbps | 47.2 Kbps |
| G.728 | 16 Kbps | 31.5 Kbps |
| iLBC | 15 Kbps | 27.7 Kbps |
NEB = Nominal Ethernet Bandwidth (one direction)
- G711u/a - Requires 64+Kbps (inbound and outbound) continuous data stream for a quality call, plus the SIP signal. A 128Kbps connection has shown to be the minimal connection needed in our testing.
- G723 - Requires 6.4+Kbps (I and O) continuous data stream and also needs room for the SIP signal, 28.8Kbps connection has shown to be the minimal connection.
(Source)
