Engineering a Mixed Vendor Solution
Given the previous discussion, it should now be clear that a mixed vendor solution
should be approached with caution.There are circumstances where a mixed environment
may actually work, such as installing VoIP at a small branch office where
a single IP subnet is to be used for up to 20 users. In this case, any compliant Fast
Ethernet switch would work fine without the need for establishing VLANs, except
that you’d need to use the external power adapters for the IP phones themselves.
Another issue with mixed vendor solutions is that even on a flat network, a thirdparty
Fast Ethernet switch might not be configurable for port-based Quality of
Service (QoS) or for Type of Service (ToS) tagging that VoIP solutions sometimes
require for proper operations.There are some solutions where this is not an issue,
and yet others where it ends up as a complete catastrophe.
The main point to be made is that if you decide on a mixed vendor solution,
you inherently accept the risks of having something go wrong with the installation.
When this occurs, Cisco isn’t likely to be of much help to you troubleshooting
other vendor’s equipment and problems. Cisco isn’t being rude about it,
just realistic—they have no idea how well that vendor’s solution might or might
not be.