1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
/*
* Copyright (c) 2006-2009 by the Protocol Engineering Lab, U of Delaware
* All rights reserved.
*
* Protocol Engineering Lab web page : http://pel.cis.udel.edu/
*
* Paul D. Amer <amer@@cis,udel,edu>
* Armando L. Caro Jr. <acaro@@cis,udel,edu>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the University nor of the Laboratory may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/* This extension combines MultipleFastRtx and HbAfterRto extensions.
*
* MultipleFastRtx extension implements the Caro Multiple Fast Retransmit
* Algorithm. Caro's Algorithm introduces a fastRtxRecover state variable
* per TSN in the send buffer. Any time a TSN is retransmitted, its
* fastRtxRecover is set to the highest TSN outstanding at the time of
* retransmit. That way, only missing reports triggered by TSNs beyond
* fastRtxRecover may trigger yet another fast retransmit.
*
* HbAfterRto extension sends a heartbeat immediately after timeout
* retransmission. The idea is to give the destinations a chance to get an
* RTT measurement after their RTO is backed off. The hope is to avoid
* unnecessarily large RTOs (especially on the alternate destinations).
*/
#ifndef lint
static const char rcsid[] =
"@(#) $Header: /cvsroot/nsnam/ns-2/sctp/sctp-mfrHbAfterRto.cc,v 1.3 2009/11/16 05:51:27 tom_henderson Exp $ (UD/PEL)";
#endif
#include "ip.h"
#include "sctp-mfrHbAfterRto.h"
#include "flags.h"
#include "random.h"
#include "template.h"
#include "sctpDebug.h"
#ifdef DMALLOC
#include "dmalloc.h"
#endif
#define MIN(x,y) (((x)<(y))?(x):(y))
#define MAX(x,y) (((x)>(y))?(x):(y))
static class MfrHbAfterRtoSctpClass : public TclClass
{
public:
MfrHbAfterRtoSctpClass() : TclClass("Agent/SCTP/MfrHbAfterRto") {}
TclObject* create(int, const char*const*)
{
return (new MfrHbAfterRtoSctpAgent());
}
} classSctpMfrHbAfterRto;
MfrHbAfterRtoSctpAgent::MfrHbAfterRtoSctpAgent() : MultipleFastRtxSctpAgent()
{
}
void MfrHbAfterRtoSctpAgent::delay_bind_init_all()
{
MultipleFastRtxSctpAgent::delay_bind_init_all();
}
int MfrHbAfterRtoSctpAgent::delay_bind_dispatch(const char *cpVarName,
const char *cpLocalName,
TclObject *opTracer)
{
return MultipleFastRtxSctpAgent::delay_bind_dispatch(cpVarName,
cpLocalName, opTracer);
}
void MfrHbAfterRtoSctpAgent::Timeout(SctpChunkType_E eChunkType,
SctpDest_S *spDest)
{
DBG_I(Timeout);
DBG_PL(Timeout, "eChunkType=%s spDest=%p"),
(eChunkType == SCTP_CHUNK_DATA) ? "DATA" : "HEARTBEAT",
spDest
DBG_PR;
double dCurrTime = Scheduler::instance().clock();
DBG_PL(Timeout, "dCurrTime=%f"), dCurrTime DBG_PR;
if(eChunkType == SCTP_CHUNK_DATA)
{
spDest->eRtxTimerIsRunning = FALSE;
/* section 7.2.3 of rfc2960 (w/ implementor's guide)
*/
if(spDest->iCwnd > 1 * (int) uiMaxDataSize)
{
spDest->iSsthresh = MAX(spDest->iCwnd/2,
iInitialCwnd * (int) uiMaxDataSize);
spDest->iCwnd = 1*uiMaxDataSize;
spDest->iPartialBytesAcked = 0; // reset
tiCwnd++; // trigger changes for trace to pick up
}
spDest->opCwndDegradeTimer->force_cancel();
/* Cancel any pending RTT measurement on this destination. Stephan
* Baucke suggested (2004-04-27) this action as a fix for the
* following simple scenario:
*
* - Host A sends packets 1, 2 and 3 to host B, and choses 3 for
* an RTT measurement
*
* - Host B receives all packets correctly and sends ACK1, ACK2,
* and ACK3.
*
* - ACK2 and ACK3 are lost on the return path
*
* - Eventually a timeout fires for packet 2, and A retransmits 2
*
* - Upon receipt of 2, B sends a cumulative ACK3 (since it has
* received 2 & 3 before)
*
* - Since packet 3 has never been retransmitted, the SCTP code
* actually accepts the ACK for an RTT measurement, although it
* was sent in reply to the retransmission of 2, which results
* in a much too high RTT estimate. Since this case tends to
* happen in case of longer link interruptions, the error is
* often amplified by subsequent timer backoffs.
*/
spDest->eRtoPending = FALSE; // cancel any pending RTT measurement
}
DBG_PL(Timeout, "was spDest->dRto=%f"), spDest->dRto DBG_PR;
spDest->dRto *= 2; // back off the timer
if(spDest->dRto > dMaxRto)
spDest->dRto = dMaxRto;
tdRto++; // trigger changes for trace to pick up
DBG_PL(Timeout, "now spDest->dRto=%f"), spDest->dRto DBG_PR;
spDest->iTimeoutCount++;
spDest->iErrorCount++; // @@@ window probe timeouts should not be counted
DBG_PL(Timeout, "now spDest->iErrorCount=%d"), spDest->iErrorCount DBG_PR;
if(spDest->eStatus == SCTP_DEST_STATUS_ACTIVE)
{
iAssocErrorCount++;
DBG_PL(Timeout, "now iAssocErrorCount=%d"), iAssocErrorCount DBG_PR;
// Path.Max.Retrans exceeded?
if(spDest->iErrorCount > (int) uiPathMaxRetrans)
{
spDest->eStatus = SCTP_DEST_STATUS_INACTIVE;
if(spDest == spNewTxDest)
{
spNewTxDest = GetNextDest(spDest);
DBG_PL(Timeout, "failing over from %p to %p"),
spDest, spNewTxDest DBG_PR;
}
}
if(iAssocErrorCount > (int) uiAssociationMaxRetrans)
{
/* abruptly close the association! (section 8.1)
*/
DBG_PL(Timeout, "abruptly closing the association!") DBG_PR;
Close();
DBG_X(Timeout);
return;
}
}
// trace it!
tiTimeoutCount++;
tiErrorCount++;
if(spDest->iErrorCount > (int) uiChangePrimaryThresh &&
spDest == spPrimaryDest)
{
spPrimaryDest = spNewTxDest;
DBG_PL(Timeout, "changing primary from %p to %p"),
spDest, spNewTxDest DBG_PR;
}
if(eChunkType == SCTP_CHUNK_DATA)
{
TimeoutRtx(spDest);
// BEGIN -- HbAfterRto changes to this function
/* If there is an active alternate destination, then send a HB
* immediately to the destination which timed out.
*/
if(GetNextDest(spDest) != spDest)
SendHeartbeat(spDest);
// END -- HbAfterRto changes to this function
}
else if(eChunkType == SCTP_CHUNK_HB)
{
if(uiHeartbeatInterval != 0)
SendHeartbeat(spDest);
}
DBG_X(Timeout);
}
|
