Enhanced algorithms for consistent network updates

PPCU: Proportional per-packet consistent updates for Software Defined Networks

“…Why the number of switches involved in the update must be less: Algorithms that perform a Rules Update while preserving PPC either 1) need to update all the switches B in the network [7] [16] or 2) identify paths affected by S and update all the switches along those paths [1] [17] or 3) update only S and all the ingresses [18] [19], regardless of the number of elements in S and regardless of the number of rules to be updated.…”

“…22: end if 23: end if 24: end while 25: end procedure Algorithm at the control plane: This section first specifies the algorithm for the control plane, at the controller (Algorithm 1) and at each s i ∈ S (Algorithm 2) and later for the data plane, in Algorithm 3. The message exchanges below are the same as in [16] and [18]; the parameters in them and actions upon receiving them have been modified to suit PPCU.…”

“…We add to and evaluate using the parameters of interest identified for a PPC in [16]: 1) Overlap: Duration for which the old and new rules exist at each type of switch 2) Transition The purpose of the analysis is to understand what the above depend upon and to compare with a single update in E2PU (using rule updates in TCAMs) [16], which updates switches using 2PU with 3 rounds of message exchanges, and with the algorithm in [19]. We assume that [19] uses acknowledgements for each message sent.…”

“…r 1 must check if f p2 = 1 in the action (lines 5 and 6). 4) Case 4, s f receives "Commit OK" last: To solve this problem, illustrated in Figure 3, r 0 must set f p1 = 1 and check for f p1 = 1 in the action (lines 16,17). r 1 must check for f p1 = 0 in its match field , so that r 1 rules in subsequent affected switches do not match this packet and therefore always match r 0 .…”