I am wondering if a routing/forwarding table update at a switching node (e.x., a switch or layer-3 router) can cause momentary packet drop or increased delay for a data stream that will traverse this switching node. For example, given the following topology:
Sender -- S1 -- S2----S4 -- Receiver \ / --- S3--
There is a constant data stream (e.x. TCP stream) flowing from the sender to the receiver. The routing/forwarding entry at S1 instructs S1 to forward the sender's packet to S2. Therefore, the path is sender->s1->s2->s4->receiver. However, let's say at one moment a routing table update command is issued at S1, telling S1 to now forward the sender's packet to S3 (so the new path will be sender->s1->s3->s4->receiver). Will this routing table update at that moment causes S1 or the network to drop some packets or delay the transmission? If so, how long will that roughly take?
My thought is that when the routing entry is overwritten, maybe that entry is locked from being read before the update is completed. Therefore, arriving packets may be waiting in the queue, which causes some delay. Also, if the queue is full, maybe the arriving packets will be dropped.
Thank you in advance!