Download  Print this page

Flow Masks; Layer 3-switched Packet Rewrite - Cisco 6500 Series Software Configuration Manual

Hide thumbs
   
1
2
Table of Contents
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
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570

Advertisement

Chapter 20
Configuring IPX Unicast Layer 3 Switching on Supervisor Engine 1
The state and identity of the flow are maintained while packet traffic is active; when traffic for a flow
ceases, the entry ages out. You can configure the aging time for IPX MLS entries kept in the MLS cache.
If an entry is not used for the specified period of time, the entry ages out and statistics for that flow can
be exported to a flow collector application.
The maximum MLS cache size is 128K entries. However, an MLS cache larger than 32K entries
increases the probability that a flow will not be switched by the PFC and will get forwarded to the MSFC.

Flow Masks

The PFC uses flow mask modes to determine how IPX MLS entries are created. The flow mask mode is
based on the access lists configured on the IPX MLS router interfaces.
These sections describe how the flow mask modes work:
Flow Mask Modes
The PFC supports only one flow mask (the most specific one). When the PFC flow mask changes, the
entire MLS cache is purged. When the PFC exports cached entries, flow records are created based on the
current flow mask mode. Depending on the current mode, some fields in the flow record might not have
values. Unsupported fields are filled with a dash (-).
The flow mask modes for IPX MLS are as follows:
Flow Mask Mode and show mls entry Command Output
The flow mask mode impacts the screen output of the show mls ipx command. In destination mode, the
destination IPX address of the switched flows are displayed, along with the packet rewrite information:
rewritten destination MAC, rewritten VLAN, and egress interface.

Layer 3-Switched Packet Rewrite

When a packet is Layer 3 switched from a source host to a destination host, the PFC performs a packet
rewrite, based on information learned from the MSFC and stored in the MLS cache.
If Host A and Host B are on different VLANs and Host A sends a packet to the MSFC to be routed to
Host B, the PFC recognizes that the packet was sent to the MAC address of the MSFC. The PFC checks
the MLS cache and finds the entry matching the flow in question.
78-14099-04
Flow Mask Modes, page 20-3
Flow Mask Mode and show mls entry Command Output, page 20-3
destination mode—The least-specific flow mask mode. The PFC maintains one IPX MLS entry for
each destination IPX address (network and node). All flows to a given destination IPX address use
this IPX MLS entry. This mode is used if there are no access lists configured based on source IPX
addresses on any of the IPX MLS router interfaces.
destination-source mode—The PFC maintains one MLS entry for each destination (network and
node) and source (network only) IPX address pair. All flows between a given source and destination
use this MLS entry regardless of the IPX sockets. This mode is used if there is an access list on any
of the IPX MLS interfaces that filters on source network.
Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
Understanding How IPX MLS Works
20-3

Advertisement

Table of Contents

   Related Manuals for Cisco 6500 Series

Comments to this Manuals

Symbols: 0
Latest comments: