communication between two subnet masks

this may be a silly question. i hav开发者_如何学编程e created a subnet on my network of 10.55.0.0/21. the network already had a subnet of 10.55.1.0/24.

My question is why can a /21 address communicate with a /24 address and vice versa?

regards,

DPERROTT

Your /21 network includes the /24 network. If you want them to be separate and want to route between them, create non-overlapping subnets, say make the new one 10.55.2/24.