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Checking references for intended status: Informational ---------------------------------------------------------------------------- -- Obsolete informational reference (is this intentional?): RFC 3315 (Obsoleted by RFC 8415) Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group T. Lemon 3 Internet-Draft Nominum, Inc. 4 Intended status: Informational T. Mrugalski 5 Expires: January 5, 2015 Internet Systems Consortium, Inc. 6 July 4, 2014 8 Customizing DHCP Configuration on the Basis of Network Topology 9 draft-ietf-dhc-topo-conf-02 11 Abstract 13 DHCP servers have evolved over the years to provide significant 14 functionality beyond that which is described in the DHCP base 15 specifications. One aspect of this functionality is support for 16 context-specific configuration information. This memo describes some 17 such features and makes recommendations as to how they can be used. 19 Status of This Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at http://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on January 5, 2015. 36 Copyright Notice 38 Copyright (c) 2014 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 3. Locality . . . . . . . . . . . . . . . . . . . . . . . . . . 3 56 4. Simple Subnetted Network . . . . . . . . . . . . . . . . . . 8 57 5. Relay agent running on a host . . . . . . . . . . . . . . . . 10 58 6. Cascade relays . . . . . . . . . . . . . . . . . . . . . . . 10 59 7. Regional Configuration Example . . . . . . . . . . . . . . . 11 60 8. Dynamic Lookup . . . . . . . . . . . . . . . . . . . . . . . 13 61 9. Multiple subnets on the same link . . . . . . . . . . . . . . 14 62 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 63 11. Security Considerations . . . . . . . . . . . . . . . . . . . 14 64 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 65 13. Informative References . . . . . . . . . . . . . . . . . . . 15 66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 68 1. Introduction 70 The DHCPv4 [RFC2131] and DHCPv6 [RFC3315] protocol specifications 71 describe how addresses can be allocated to clients based on network 72 topology information provided by the DHCP relay infrastructure. 73 Address allocation decisions are integral to the allocation of 74 addresses and prefixes in DHCP. 76 The DHCP protocol also describes mechanisms for provisioning devices 77 with additional configuration information; for example, DNS [RFC1034] 78 server addresses, default DNS search domains, and similar 79 information. 81 Although it was the intent of the authors of these specifications 82 that DHCP servers would provision devices with configuration 83 information appropriate to each device's location on the network, 84 this practice was never documented, much less described in detail. 86 Existing DHCP server implementations do in fact provide such 87 capabilities; the goal of this document is to describe those 88 capabilities for the benefit both of operators and of protocol 89 designers who may wish to use DHCP as a means for configuring their 90 own services, but may not be aware of the capabilities provided by 91 most modern DHCP servers. 93 2. Terminology 95 o Routable IP address: an IP address with a scope of use wider than 96 the local link. 98 o PE router: Provider Edge Router. The provider router closest to 99 the customer. 101 o CPE device: customer premise equipment device. Typically a router 102 belonging to the customer that connects directly to the provider 103 link. 105 o Shared subnet: a case where two or more subnets of the same 106 protocol family are available on the same link. 'Share subnet' 107 terminology is typically used in Unix environments. It is 108 typically called 'multinet' in Windows environment. The 109 administrative configuration inside a Microsoft DHCP server is 110 called 'DHCP Superscope'. 112 3. Locality 114 Figure 1 illustrates a simple hierarchy of network links with Link D 115 serving as a backbone to which the DHCP server is attached. 117 Figure 2 illustrates a more complex case. Although some of its 118 aspects are unlikely to be seen in an actual production networks, 119 they are beneficial for explaining finer aspects of the DHCP 120 protocols. Note that some nodes act as routers (which forward all 121 IPv6 traffic) and some are relay agents (i.e. run DHCPv6 specific 122 software that forwards only DHCPv6 traffic). 124 Link A Link B 125 |===+===========| |===========+======| 126 | | 127 | | 128 +---+---+ +---+---+ 129 | relay | | relay | 130 | A | | B | 131 +---+---+ +---+---+ 132 | | 133 | Link C | 134 |===+==========+=================+======| 135 | 136 | 137 +----+---+ +--------+ 138 | router | | DHCP | 139 | A | | Server | 140 +----+---+ +----+---+ 141 | | 142 | | 143 | Link D | 144 |==============+=================+======| 145 | 146 | 147 +----+---+ 148 | router | 149 | B | 150 +----+---+ 151 | 152 | 153 |===+==========+=================+======| 154 | Link E | 155 | | 156 +---+---+ +---+---+ 157 | relay | | relay | 158 | C | | D | 159 +---+---+ +---+---+ 160 | | 161 | | 162 |===+===========| |===========+======| 163 Link F Link G 165 Figure 1: A simple network 167 Link A Link B Link H 168 |===+==========| |=========+======| |======+======| 169 | | | 170 | | | 171 +---+---+ +---+---+ +---+---+ 172 | relay | | relay | | relay | 173 | A | | B | | G | 174 +---+---+ +---+---+ +---+---+ 175 | | | 176 | Link C | | Link J 177 |===+==========+==============+======| |======+======| 178 | | 179 | | 180 +----+---+ +--------+ +---+---+ 181 | router | | DHCP | | relay | 182 | A | | Server | | F | 183 +----+---+ +----+---+ +---+---+ 184 | | | 185 | | | 186 | Link D | | 187 |==============+=========+=======+=============+======| 188 | | 189 | | 190 +----+---+ +---+---+ 191 | router | | relay | 192 | B | | E | 193 +----+---+ +---+---+ 194 | | 195 | | 196 |===+==========+=========+=======+======| 197 | Link E | 198 | | 199 +---+---+ +---+---+ 200 | relay | | relay | 201 | C | | D | 202 +---+---+ +---+---+ 203 | | 204 | | 205 |===+===========| |===========+======| 206 Link F Link G 208 Figure 2: Complex network 210 This diagram allows us to represent a variety of different network 211 configurations and illustrate how existing DHCP servers can provide 212 configuration information customized to the particular location from 213 which a client is making its request. 215 It's important to understand the background of how DHCP works when 216 considering this diagram. DHCP clients are assumed not to have 217 routable IP addresses when they are attempting to obtain 218 configuration information. 220 The reason for making this assumption is that one of the functions of 221 DHCP is to bootstrap the DHCP client's IP address configuration; if 222 the client does not yet have an IP address configured, it cannot 223 route packets to an off-link DHCP server, therefore some kind of 224 relay mechanism is required. 226 The details of how packet delivery between clients and servers works 227 are different between DHCPv4 and DHCPv6, but the essence is the same: 228 whether or not the client actually has an IP configuration, it 229 generally communicates with the DHCP server by sending its requests 230 to a DHCP relay agent on the local link; this relay agent, which has 231 a routable IP address, then forwards the DHCP requests to the DHCP 232 server. In some cases in DHCPv4, when a DHCP client has a routable 233 IPv4 address, the message is unicast to the DHCP server rather than 234 going through a relay agent. In DHCPv6 that is also possible in case 235 where the server is configured with a Server Unicast option (see 236 Section 22.12 in [RFC3315]) and clients are able to take advantage of 237 it. In such case once the clients get their (presumably global) 238 addresses, they are able to contact server directly, bypassing 239 relays. It should be noted that such a mode is completely 240 controllable by administrators in DHCPv6. (They may simply choose to 241 not configure server unicast option, thus forcing clients to send 242 their messages always via relay agents). 244 In all cases, the DHCP server is able to obtain an IP address that it 245 knows is on-link for the link to which the DHCP client is connected: 246 either the DHCPv4 client's routable IPv4 address, or the relay 247 agent's IPv4 address on the link to which the client is connected. 248 So in every case the server is able to determine the client's point 249 of attachment and select appropriate subnet- or link-specific 250 configuration. 252 In the DHCPv6 protocol, there are two mechanisms defined in [RFC3315] 253 that allow server to distinguish which link the relay agent is 254 connected to. The first mechanism is a link-address field in the 255 RELAY-FORW and RELAY-REPL messages. Somewhat contrary to its name, 256 relay agents insert in the link-address field an address that is 257 typically global and can be used to uniquely identify the link on 258 which the client is located. In normal circumstances this is the 259 solution that is easiest to maintain. It requires, however, for the 260 relay agent to have an address with a scope larger than link-local 261 configured on its client-facing interface. If for whatever reason 262 that is not feasible (e.g. because the relay agent does not have a 263 global address configured on the client-facing interface), the relay 264 agent includes an Interface-Id option (see Section 22.18 of 265 [RFC3315]) that identifies the link clients are connected to. It is 266 up to administrator to make sure that the interface-id is unique 267 within his administrative domain. It should be noted that RELAY-FORW 268 and RELAY-REPL messages are exchanged between relays and servers 269 only. Clients are never exposed to those messages. Also, servers 270 never receive RELAY-REPL messages. Relay agents must be able to 271 process both RELAY-FORW (sending already relayed message further 272 towards the server, when there is more than one relay agent in a 273 chain) and RELAY-REPL (when sending back the response towards the 274 client, when there is more than one relay agent in a chain). 276 DHCPv6 also has support for more finely grained link identification, 277 using Lightweight DHCPv6 Relay Agents [RFC6221] (LDRA). In this 278 case, in addition to receiving an IPv6 address that is on-link for 279 the link to which the client is connected, the DHCPv6 server also 280 receives an Interface-Id option from the relay agent that can be used 281 to more precisely identify the client's location on the network. 283 What this means in practice is that the DHCP server in all cases has 284 sufficient information to pinpoint, at the very least, the layer 3 285 link to which the client is connected, and in some cases which layer 286 2 link the client is connected to, when the layer 3 link is 287 aggregated out of multiple layer 2 links. 289 In all cases, then, the DHCP server will have a link-identifying IP 290 address, and in some cases it may also have a link-specific 291 identifier (e.g. Interface-Id Option or Link Address Option defined 292 in Section 5 of [RFC6977]). It should be noted that there is no 293 guarantee that the link-specific identifier will be unique outside 294 the scope of the link-identifying IP address. 296 It is also possible for link-specific identifiers to be nested, so 297 that the actual identifier that identifies the link is an aggregate 298 of two or more link-specific identifiers sent by a set of LDRAs in a 299 chain; in general this functions exactly as if a single identifier 300 were received from a single LDRA, so we do not treat it specially in 301 the discussion below, but sites that use chained LDRA configurations 302 will need to be aware of this when configuring their DHCP servers. 304 So let's examine the implications of this in terms of how a DHCP 305 server can deliver targeted supplemental configuration information to 306 DHCP clients. 308 4. Simple Subnetted Network 310 Consider Figure 1 in the context of a simple subnetted network. In 311 this network, there are four leaf subnets: links A, B, F and G, on 312 which DHCP clients will be configured. Relays A, B, C and D in this 313 example are represented in the diagram as IP routers with an embedded 314 relay function, because this is a very typical configuration, but the 315 relay function can also be provided in a separate node on each link. 317 In a simple network like this, there may be no need for link-specific 318 configuration in DHCPv6, since local routing information is delivered 319 through router advertisements. However, in IPv4, it is very typical 320 to configure the default route using DHCP; in this case, the default 321 route will be different on each link. In order to accomplish this, 322 the DHCP server will need link-specific configuration for the default 323 route. 325 To illustrate, we will use an example from a hypothetical DHCP server 326 that uses a simple JSON notation for configuration. Although we know 327 of no DHCP server that uses this specific syntax, most modern DHCP 328 server provides similar functionality. 330 { 331 "prefixes": { 332 "192.0.2.0/26": { 333 "options": { 334 "routers": ["192.0.2.1"] 335 }, 336 "on-link": ["a"] 337 }, 338 "192.0.2.64/26": { 339 "options": { 340 "routers": ["192.0.2.65"] 341 }, 342 "on-link": ["b"] 343 }, 344 "192.0.2.128/26": { 345 "options": { 346 "routers": ["192.0.2.129"] 347 }, 348 "on-link": ["f"] 349 }, 350 "192.0.2.192/26": { 351 "options": { 352 "routers": ["192.0.2.193"] 353 }, 354 "on-link": ["g"] 355 } 356 } 357 } 359 Figure 3: Configuration example 361 In Figure 3, we see a configuration example for this scenario: a set 362 of prefixes, each of which has a set of options and a list of links 363 for which it is on-link. We have defined one option for each prefix: 364 a routers option. This option contains a list of values; each list 365 only has one value, and that value is the IP address of the router 366 specific to the prefix. 368 When the DHCP server receives a request, it searches the list of 369 prefixes for one that encloses the link-identifying IP address 370 provided by the client or relay agent. The DHCP server then examines 371 the options list associated with that prefix and returns those 372 options to the client. 374 So for example a client connected to link A in the example would have 375 a link-identifying IP address within the 192.0.2.0/26 prefix, so the 376 DHCP server would match it to that prefix. Based on the 377 configuration, the DHCP server would then return a routers option 378 containing a single IP address: 192.0.2.1. A client on link F would 379 have a link-identifying address in the 192.0.2.128/26 prefix, and 380 would receive a routers option containing the IP address 192.0.2.129. 382 5. Relay agent running on a host 384 Relay agent is a DHCP software that may be run on any IP node. 385 Although it is typically run on a router, this is by no means 386 required by the DHCP protocol. The relay agent is simply a service 387 that operates on a link, receiving link-local multicasts or 388 broadcasts and relaying them, using IP routing, to a DHCP server. As 389 long as the relay has an IP address on the link, and a default route 390 or more specific route through which it can reach a DHCP server, it 391 need not be a router, or even have multiple interfaces. 393 Relay agent can be run on a host connected to two links. That case 394 is presented in Figure 2. There is router B that is connected to 395 links D and E. At the same time there is also a host that is 396 connected to the same links. The relay agent software is running on 397 that host. That is uncommon, but legal configuration. 399 6. Cascade relays 401 Let's observe another case shown in Figure 2. Note that in typical 402 configuration, the clients connected to link G will send their 403 requests to relay D which will forward its packets directly to the 404 DHCP server. That is typical, but not the only possible 405 configuration. It is possible to configure relay agent D to forward 406 client messages to relay E which in turn will send it to the DHCP 407 server. This configuration is sometimes referred to as cascade relay 408 agents. 410 Note that the relaying mechanism works differently in DHCPv4 and in 411 DHCPv6. In DHCPv4 only the first relay is able to set the GIADDR 412 field in the DHCPv4 packet. Any following relays that receive that 413 packet will not change it as the server needs GIADDR information from 414 the first relay (i.e. the closest to the client). Server will send 415 the response back to the GIADDR address, which is the address of the 416 first relay agent that saw the client's message. That means that the 417 client messages travel on a different path than the server's 418 responses. A message from client connected to link G will travel via 419 relay D, relay E and to the server. A response message will be sent 420 from the server to relay D via router B, and relay D will send it to 421 the client on link G. 423 Relaying in DHCPv6 is more structured. Each relay agent encapsulates 424 a packet that is destined to the server and sends it towards the 425 server. Depending on the configuration that can be server's unicast 426 address, a multicast address or next relay agent address. The next 427 relay repeats the encapsulation process. Although the resulting 428 packet is more complex (may have up to 32 levels of encapsulation if 429 traveled through 32 relays), every relay may insert its own options 430 and it is clear which relay agent inserted which option. 432 7. Regional Configuration Example 434 In this example, link C is a regional backbone for an ISP. Link E is 435 also a regional backbone for that ISP. Relays A, B, C and D are PE 436 routers, and Links A, B, F and G are actually link aggregators with 437 individual layer 2 circuits to each customer--for example, the relays 438 might be DSLAMs or cable head-end systems. At each customer site we 439 assume there is a single CPE device attached to the link. 441 We further assume that links A, B, F and G are each addressed by a 442 single prefix, although it would be equally valid for each CPE device 443 to be numbered on a separate prefix. 445 In a real-world deployment, there would likely be many more than two 446 PE routers connected to each regional backbone; we have kept the 447 number small for simplicity. 449 In the example presented in Figure 4, the goal is to configure all 450 the devices within a region with server addresses local to that 451 region, so that service traffic does not have to be routed between 452 regions unnecessarily. 454 { 455 "prefixes": { 456 "2001:db8:0:0::/40": { 457 "on-link": ["A"] 458 }, 459 "2001:db8:100:0::/40": { 460 "on-link": ["B"] 461 }, 462 "2001:db8:200:0::/40": { 463 "on-link": ["F"] 464 }, 465 "2001:db8:300:0::/40": { 466 "on-link": ["G"] 467 } 468 }, 469 "links": { 470 "A": {"region": "omashu"}, 471 "B": {"region": "omashu"}, 472 "F": {"region": "gaoling"}, 473 "G": {"region": "gaoling"} 474 }, 475 "regions": { 476 "omashu": { 477 "options": { 478 "sip-servers": ["sip.omashu.example.org"], 479 "dns-servers": ["dns1.omashu.example.org", 480 "dns2.omashu.example.org"] 481 } 482 }, 483 "gaoling": { 484 "options": { 485 "sip-servers": ["sip.gaoling.example.org"], 486 "dns-servers": ["dns1.gaoling.example.org", 487 "dns2.gaoling.example.org"] 488 } 489 } 490 } 491 } 493 Figure 4: An example regions configuration 495 In this example, when a request comes in to the DHCP server with a 496 link-identifying IP address in the 2001:DB8:0:0::/40 prefix, it is 497 identified as being on link A. The DHCP server then looks on the 498 list of links to see what region the client is in. Link A is 499 identified as being in omashu. The DHCP server then looks up omashu 500 in the set of regions, and discovers a list of region-specific 501 options. 503 The DHCP server then resolves the domain names listed in the options 504 and sends a sip-server option containing the IP addresses that the 505 resolver returned for sip.omashu.example.org, and a dns-server option 506 containing the IP addresses returned by the resolver for 507 dns1.omashu.example.org and dns2.omashu.example.org. Depending on 508 the server capability and configuration, it may cache resolved 509 responses for specific period of time, repeat queries every time or 510 even keep the response until reconfiguration or shutdown. 512 Similarly, if the DHCP server receives a request from a DHCP client 513 where the link-identifying IP address is contained by the prefix 514 2001:DB8:300:0::/40, then the DHCP server identifies the client as 515 being connected to link G. The DHCP server then identifies link G as 516 being in the gaoling region, and returns the sip-servers and dns- 517 servers options specific to that region. 519 As with the previous example, the exact configuration syntax and 520 structure shown above does not precisely match what existing DHCP 521 servers do, but the behavior illustrated in this example can be 522 accomplished with most existing modern DHCP servers. 524 8. Dynamic Lookup 526 In the Regional example, the configuration listed several domain 527 names as values for the sip-servers and dns-servers options. The 528 wire format of both of these options contains one or more IPv6 529 addresses--there is no way to return a domain name to the client. 531 This was understood to be an issue when the original DHCP protocol 532 was defined, and historical implementations even from the very early 533 days would accept domain names and resolve them. Some early DHCP 534 implementations, particularly those based on earlier BOOTP 535 implementations, had very limited capacity for reconfiguration. 537 However, most modern DHCP servers handle name resolution by querying 538 the resolver each time a DHCP packet comes in. This means that if 539 DHCP servers and DNS servers are managed by different administrative 540 entities, there is no need for the administrators of the DHCP servers 541 and DNS servers to communicate when changes are made. When changes 542 are made to the DNS server, these changes are promptly and 543 automatically adopted by the DHCP server. Similarly, when DHCP 544 server configurations change, DNS server administrators need not be 545 aware of this. 547 However, it should be noted that even though the DHCP server may be 548 configured to query the DNS server every time it uses configured 549 names, the changes made in the DNS zone may not be visible to the 550 server until the DNS cache expires. If this is not desired, the DHCP 551 server can be configured to query the authoritative DNS server 552 directly, bypassing any caching DNS servers. 554 It's worth noting that DNS is not the only way to resolve names, and 555 not all DHCP servers support other techniques (e.g., NIS+ or WINS). 556 However, since these protocols have all but vanished from common use, 557 this won't be an issue in new deployments. 559 9. Multiple subnets on the same link 561 There are scenarios where there is more than one subnet from the same 562 protocol family (i.e. two or more IPv4 subnets or two or more IPv6 563 subnets) configured on the same layer 3 link. One example is a slow 564 network renumbering where some services are migrated to the new 565 addressing scheme, but some aren't yet. Second example is a cable 566 network, where cable modems and the devices connected behind them are 567 connected to the same layer 2 link. However, operators want the 568 cable modems and user devices to get addresses from distinct address 569 spaces, so users couldn't easily access their modems management 570 interfaces. Such a configuration is often referred to as 'shared 571 subnets' in Unix environments or 'multinet' in Microsoft terminology. 573 To support such an configuration, additional differentiating 574 information is required. Many DHCP server implementations offer a 575 feature that is typically called client classification. The server 576 segregates incoming packets into one or more classes based on certain 577 packet characteristics, e.g. presence or value of certains options or 578 even a match between existing options. Servers require additional 579 information to handle such configuration, as it can't use the 580 topographical property of the relay addresses alone to properly 581 choose a subnet. Such information is always implementation specific. 583 10. Acknowledgments 585 Thanks to Dave Thaler for suggesting that even though "everybody 586 knows" how DHCP servers are deployed in the real world, it might be 587 worthwhile to have an IETF document that explains what everybody 588 knows, because in reality not everybody is an expert in how DHCP 589 servers are administered. Thanks to Andre Kostur, Carsten Strotmann, 590 Simon Perreault, Jinmei Tatuya and Suresh Krishnan for their reviews, 591 comments and feedback. 593 11. Security Considerations 595 This document explains existing practice with respect to the use of 596 Dynamic Host Configuration Protocol [RFC2131] and Dynamic Host 597 Configuration Protocol Version 6 [RFC3315]. The security 598 considerations for these protocols are described in their 599 specifications and in related documents that extend these protocols. 600 This document introduces no new functionality, and hence no new 601 security considerations. 603 12. IANA Considerations 605 The IANA is hereby absolved of any requirement to take any action in 606 relation to this document. 608 13. Informative References 610 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 611 STD 13, RFC 1034, November 1987. 613 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 614 2131, March 1997. 616 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 617 and M. Carney, "Dynamic Host Configuration Protocol for 618 IPv6 (DHCPv6)", RFC 3315, July 2003. 620 [RFC6221] Miles, D., Ooghe, S., Dec, W., Krishnan, S., and A. 621 Kavanagh, "Lightweight DHCPv6 Relay Agent", RFC 6221, May 622 2011. 624 [RFC6977] Boucadair, M. and X. Pougnard, "Triggering DHCPv6 625 Reconfiguration from Relay Agents", RFC 6977, July 2013. 627 Authors' Addresses 629 Ted Lemon 630 Nominum, Inc. 631 2000 Seaport Blvd 632 Redwood City, CA 94063 633 USA 635 Phone: +1-650-381-6000 636 Email: Ted.Lemon@nominum.com 638 Tomek Mrugalski 639 Internet Systems Consortium, Inc. 640 950 Charter Street 641 Redwood City, CA 94063 642 USA 644 Phone: +1 650 423 1345 645 Email: tomasz.mrugalski@gmail.com