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# This topology (SimpleRelayWithCongestion) is designed for testing simple 

# network congestion on a InteriorRouter. You can change its behaviour by 

# defining multiple variables for EFCP, RMT and FA. Several implications needs 

# to be taken into account when defining these variables and their mutual relations.

# For Flow Allocator it is mainly the createRequestTimeout. It specifies the 

# upper limit in which it expects response for createFlow request. So if you want 

# to avoid re-sending createFlow request, set it high enough to accomodate for 

# recursive Flow creation. It depends heavily on chosen topology.

# Default value is 10s. You can change it in .ini.

#

# Example:

# **.fa.createRequestTimeout = 12s

#

# For EFCP it is

# initialSenderCredit (default 10)

# rcvCredit (default 10)

# closedWindowQLen (default 4)

# mpl (default 50s)

# rtt (default 2s)

# initialSenderCredit     specifies the initial credit on the sender direction. 

#                     Setting this variable high (might) cause the 

#                     InteriorRouter get congested. Setting it too low will on 

#                     the other hand prevent the initial overload. After first 

#                     exchange of FlowControlPDU, the initialSenderCredit looses 

#                     its importance.

# rcvCredit           is the value that is send (in form of RcvRightWindowEdge) 

#                     in mentioned FlowControlPDU.

# closedWindowQLen        takes place when SndRightWindowEdge permits from sending 

#                     another PDU, so DTP starts to put them on closedWindowQ. 

#                     When lenght of this queue reaches closedWindowQLen, 

#                     DTP signals Push-Back to upper flow.

# mpl                     is maximum PDU lifetime and is used for computation few 

#                     inner timers. This variable is fixed throughout simulation run.

# rtt                     is initial value for round-trip time. RTT is then gradually 

#                     updated through RTTEstimator policy. Set it high enough, 

#                     so the first DataTransferPDU - Ack exchange have chance 

#                     to updated it before retransmission timer expiration.

#

# In RMT you can set defaultThreshQLength, defaultMaxQLength and maxQPolicyName.

# defaultThreshQLength    sets initial threshold length of dynamically initiated RMT 

#                     queues (10 by default).

# defaultMaxQLength   sets initial maximum length of dynamically initiated RMT 

#                     queues (20 by default, defaultMaxQLength >= defaultThreshQLength). 

# maxQPolicyName      specifies the RMT MaxQueue policy to be used in the scenario. 

#                     This policy is invoked by a queue each time number of 

#                     queued PDUs exceeds the defaultThreshQLength. The sample 

#                     MaxQueue policy used for invocation of congestion notifications 

#                     is called "UpstreamNotifier".

#

# CongestionPing:

# We are trying to congest InteriorRouter so the connection between InteriorRouter 

# and Host2 has bigger latency, queues from InteriorRouter to Host2 are shorter, etc.

#

# Used AE: AEPing - behave in same sense as ICMP Echo Request/reply

# **.host1.applicationProcess1.applicationEntity.iae.dstApName = "App2"

# **.host1.applicationProcess1.applicationEntity.iae.dstAeName = "Ping"

# **.host1.applicationProcess1.applicationEntity.iae.startAt = 10s -> start of Application entity (not start of sending PINGs)

# **.host1.applicationProcess1.applicationEntity.iae.pingAt =  60s -> AE starts sending PINGs

# **.host1.applicationProcess1.applicationEntity.iae.rate = 50 -> number of PINGs that will be sent

# **.host1.applicationProcess1.applicationEntity.iae.stopAt = 250s -> time of deallocation

# **.interiorRouter.relayIpc.relayAndMux.defaultMaxQLength = 5 -> shortened output queue towards Host2

# **.interiorRouter.relayIpc.relayAndMux.defaultThreshQLength = 3 -> lowered threshold

# **.efcp.rtt = 25s -> high enough

# **.host1.ipcProcess1.efcp.efcp.initialSenderCredit = 50 -> Host1 can send up to 50 PDUs before getting Ack or FlowControl update

# **.interiorRouter.ipcProcess1.efcp.efcp.initialSenderCredit = 3 -> But IPC towards Host2 on InteriorRouter in the lower DIF can send only up to 3 PDUs before getting Ack or FlowControl update

# **.interiorRouter.ipcProcess1.efcp.efcp.maxClosedWinQueLen = 4 -> after reaching 4 PDUs on closedWindowQ this IPC emits Push-Back

# **.host2.ipcProcess0.efcp.efcp.rcvCredit = 3 -> thanks to this, the sender credit on Interior router in ipcProcess1 stays same as initialSenderCredit even after FlowControl update.

# **.relayAndMux.maxQPolicyName = "UpstreamNotifier" -> Name of policy.

#

# Important Events:

# t=10s - created connection between Host1.ipcp1 - Host1.ipcp0

# t=10.000Xs - created connection between Host1.ipcp0 - interiorRouter.ipcp0, interiorRouter.ipcp0 - interiorRouter.relayIpc, interiorRouter.relayIpc - interiorRouter.ipcp1.

# t=15s - created connection between interiorRouter.ipcp1 - Host2.ipcp0.

# t=25s - created connection Host2.ipcp0 - Host2.ipcp1, Host2.ipcp1 - Host2.irm

# t=30s - created connection Host1.ipcp1 - Host1.irm

# t=60s - start of sending PINGs

# t=62s - interiorRouter.ipcp1 - senderCredit gets depleted (see SndRightWindowEdge -5 and NextSeqNumToSend -6)

# t=63s - interiorRouter.ipcp1 - first PDU is put on closedWindowQ

# t=66s - interiorRouter.ipcp1 - closedWindowQ is full - initiate PushBack (block upper flow),

#       -               .relayIpc - RMT shuts down port towards ipcp1 and it starts to fill

# t=70s - interiorRouter.ipcp1 - Ack is received -> there is space in closedWindowQ -> RMT port is unblocked and 1 PDU is released.

# t=70s - interiorRouter.ipcp1 - closedWindowQ is full - initiate PushBack (block upper flow) (this happens several times

# t=95s - interiorRouter.relayIpc - RMT port is full - SlowDown mechanism is invoked

#       -                         - RIBd sends CDAP message to Host1.ipcp1 to "SlowDown"

# t=95s - Host1.ipcp1 - RIBd receives CDAP message to "SlowDown" and ECNSlowDownPolicy in DTCP is initiated.

#

#

# CongestionStream

# Used AE: AEStream - Sends messages to the other side. Unlike AEPing, it does not send response back.

# Important Events:

# t=10s - created connection between Host1.ipcp1 - Host1.ipcp0

# t=10.000Xs - created connection between Host1.ipcp0 - interiorRouter.ipcp0, interiorRouter.ipcp0 - interiorRouter.relayIpc, interiorRouter.relayIpc - interiorRouter.ipcp1.

# t=15s - created connection between interiorRouter.ipcp1 - Host2.ipcp0.

# t=25s - created connection Host2.ipcp0 - Host2.ipcp1, Host2.ipcp1 - Host2.irm

# t=30s - created connection Host1.ipcp1 - Host1.irm

#

# t=60s - start of sending PINGs

# t=62s - interiorRouter.ipcp1 - senderCredit gets depleted (see SndRightWindowEdge -5 and NextSeqNumToSend -6)

# t=63s - interiorRouter.ipcp1 - first PDU is put on closedWindowQ

# t=66s - interiorRouter.ipcp1 - closedWindowQ is full - initiate PushBack (block upper flow),

#       -               .relayIpc - RMT shuts down port towards ipcp1 and it starts to fill

# t=70s - interiorRouter.ipcp1 - Ack is received -> there is space in closedWindowQ -> RMT port is unblocked and 1 PDU is released.

# t=70s - interiorRouter.ipcp1 - closedWindowQ is full - initiate PushBack (block upper flow),

# t=84s - interiorRouter.relayIpc - RMT port is full - SlowDown mechanism is invoked

#       -                         - RIBd sends CDAP message to Host1.ipcp1 to "SlowDown"

# t=84s - Host1.ipcp1 - RIBd receives CDAP message to "SlowDown" and ECNSlowDownPolicy in DTCP is initiated.