D-Link DFL-260 Product Manual - Page 170

RLB with VPN

Page 170 highlights

4.4. Route Load Balancing Chapter 4. Routing In this example, the details of the RLB scenario described above will be implemented. The assumption is made that the various IP address book objects needed have already been defined. The IP objects WAN1 and WAN2 represent the interfaces that connect to the two ISPs and the IP objects GW1 and GW2 represent the IP addresses of the gateway routers at the two ISPs. Step 1. Set up the routes in the main routing table Step 2. Create an RLB Instance object A Route Load Balancing Instance object is now created which uses the Destination algorithm will be selected to achieve stickiness so the server always sees the same source IP address (WAN1 or WAN2) from a single client. Command-Line Interface gw-world:/> add RouteBalancingInstance main Algorithm=Destination Web Interface 1. Go to Routing > Route Load Balancing > Instances > Add > Route Balancing Instance 2. The route balancing instance dialog will appear. Now select: • Routing Table: main • Algorithm: Destination • Click OK Step 3. Create IP rules to allow traffic to flow Finally, IP rules needed to be added to an IP rule set to allow traffic to flow. The detailed steps for this are not included here but the created rules would follow the pattern described above. RLB with VPN When using RLB with VPN, a number of issues need to be overcome. If we were to try and use RLB to balance traffic between two IPsec tunnels, the problem that arises is that the Remote Endpoint for any two IPsec tunnels in NetDefendOS must be different. The solutions to this issue are as follows: • Use two ISPs, with one tunnel connecting through one ISP and the other tunnel connecting through the other ISP. RLB can then be applied as normal with the two tunnels. In order to get the second tunnel to function in this case, you need to add a single host route in the main routing table that points to the secondary ISPs interface and with the secondary ISPs gateway. This solution has the advantage of providing redundancy should one ISP link fail. • Use VPN with one tunnel that is IPsec based and another tunnel that is uses a different protocol. If both tunnels must be, for example, IPsec connects, it is possible to wrap IPsec in a GRE tunnel (in other words, the IPsec tunnel is carried by a GRE tunnel). GRE is a simple tunneling protocol without encryption and therefore involves a minimum of extra overhead. See Section 3.3.5, "GRE Tunnels" for more about this topic. 170

  • 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
  • 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

In this example, the details of the RLB scenario described above will be implemented. The assumption is made
that the various IP address book objects needed have already been defined.
The IP objects
WAN1
and
WAN2
represent the interfaces that connect to the two ISPs and the IP objects
GW1
and
GW2
represent the IP addresses of the gateway routers at the two ISPs.
Step 1. Set up the routes in the
main
routing table
Step 2. Create an RLB Instance object
A Route Load Balancing Instance object is now created which uses the
Destination
algorithm will be selected to
achieve stickiness so the server always sees the same source IP address (
WAN1
or
WAN2
) from a single client.
Command-Line Interface
gw-world:/>
add RouteBalancingInstance main Algorithm=Destination
Web Interface
1.
Go to
Routing > Route Load Balancing > Instances > Add > Route Balancing Instance
2.
The route balancing instance dialog will appear. Now select:
Routing Table:
main
Algorithm:
Destination
Click
OK
Step 3. Create IP rules to allow traffic to flow
Finally, IP rules needed to be added to an IP rule set to allow traffic to flow. The detailed steps for this are not
included here but the created rules would follow the pattern described above.
RLB with VPN
When using RLB with VPN, a number of issues need to be overcome.
If we were to try and use RLB to balance traffic between two IPsec tunnels, the problem that arises
is that the
Remote Endpoint
for any two IPsec tunnels in NetDefendOS must be different. The
solutions to this issue are as follows:
Use two ISPs, with one tunnel connecting through one ISP and the other tunnel connecting
through the other ISP. RLB can then be applied as normal with the two tunnels.
In order to get the second tunnel to function in this case, you need to add a single host route in
the
main
routing table that points to the secondary ISPs interface and with the secondary ISPs
gateway.
This solution has the advantage of providing redundancy should one ISP link fail.
Use VPN with one tunnel that is IPsec based and another tunnel that is uses a different protocol.
If both tunnels must be, for example, IPsec connects, it is possible to wrap IPsec in a GRE
tunnel (in other words, the IPsec tunnel is carried by a GRE tunnel). GRE is a simple tunneling
protocol
without
encryption
and
therefore
involves
a
minimum
of
extra
overhead.
See
Section 3.3.5, “GRE Tunnels”
for more about this topic.
4.4. Route Load Balancing
Chapter 4. Routing
170