往来

There is a lot of traffic in the streets.

I know him, but I'm not in frequent contact with him.

The two sisters are in close contact. / The two sisters see a lot of each other.

Courtesy demands reciprocity.

exchange of friendly visits; friendly exchange

trade contacts; commercial exchange

keep to oneself

discontinue one's (social) contacts

block all financial dealings (with)

resume diplomatic exchanges (with)

cut oneself off from all contacts (with)

foster the communication (between)