I have a configuration that I'm desperately hoping that somebody can help me with.
I have a very large managed WAN from a telco where BGP is used as the sole routing algorithm. At the moment all sites have 2x connections a 10Mb/s primary link and a 2Mb/s backup link. There is currently no load sharing but I am being asked to make use of this 2Mb/s link to take the strain off the 10Mb/s link.
On each site we have a voice and a data VLAN. The voice traffic is about 1Mb/s and so would fit nicely on the 2Mb/s link.
Now I know that there are various options open to us to ensure that all inbound VOIP traffic is received on the 2Mb/s link, we are currently thinking of using MED to make the 2Mb/s link preferred for Voip.
My puzzle is how can I ensure that ALL outbound Voip traffic uses the 2Mb/s link. For various reasons the destination of VOIP traffic could be almost any IP address and so I am not able to use MED in a similar manner.
What I basically have to do here is to choose the outbound route based on the source subnet, rather than the destination, to ensure that all VOIP uses the 2Mb/s link and all data 10Mb/s link.
By doing this I will ensure that the traffic is completely symmetric.
Could somebody tell me what my options are for this kind of routing and point me to some links please?