group busy timer(MT2)

A timer used in multilink procedures. It is optional. At the receiving MLP, the expiration of this timer provides the means to determine that a “blocked” condition exists because buffers were exhausted before resequencing could be accomplished.; 多鏈路規程使用的一種定時器,使用與否設計者自選。多鏈路規程接收端使用該定時器 提供一種手段,當此定時器期滿時,用以確定在完成重新排序之前是否因耗盡緩沖器而存在 阻塞狀態。