Before revision:  Previous work has mostly focused on computation of expectations . We conclude with a discussion of future work, including assessment of enqueueing policies that may have smaller age of information in some cases .
After revision:  Previous work has mostly focused on computation of expectations in very particular cases. We argue that using bufferless or very small buffer systems is best and support this by simulation. We also pose some open problems including assessment of enqueueing policies that may have smaller age of information in some cases .