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diff --git a/internet-draft-satp.html b/internet-draft-satp.html index 5af3075..ba9e4db 100644 --- a/internet-draft-satp.html +++ b/internet-draft-satp.html @@ -186,7 +186,7 @@ Copyright © The IETF Trust (2007).</p> <a name="rfc.section.1"></a><h3>1. Introduction</h3> -<p>SATP is somehow a mixture of a generic encapsulation protocol like <a class='info' href='#RFC2784'>GRE<span> (</span><span class='info'>Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. Traina, “Generic Routing Encapsulation (GRE),” March 2000.</span><span>)</span></a> [3] and a secure tunneling protocol as <a class='info' href='#RFC2401'>IPsec<span> (</span><span class='info'>Kent, S. and R. Atkinson, “Security Architecture for the Internet Protocol,” November 1998.</span><span>)</span></a> [4] in tunnel mode. To save some header overhead it uses the encryption technices of <a class='info' href='#RFC3711'>SRTP<span> (</span><span class='info'>Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, “The Secure Real-time Transport Protocol (SRTP),” March 2004.</span><span>)</span></a> [1]. It supports peer to peer tunnels, where tunnel endpoints can be any combination of unicast, multicast or anycast hosts, so it defines a <a class='info' href='#RFC1546'>Host Anycast Service<span> (</span><span class='info'>Partridge, C., Mendez, T., and W. Milliken, “Host Anycasting Service,” November 1993.</span><span>)</span></a> [5] +<p>SATP is somehow a mixture of a generic encapsulation protocol like <a class='info' href='#RFC2784'>GRE<span> (</span><span class='info'>Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. Traina, “Generic Routing Encapsulation (GRE),” March 2000.</span><span>)</span></a> [4] and a secure tunneling protocol as <a class='info' href='#RFC2401'>IPsec<span> (</span><span class='info'>Kent, S. and R. Atkinson, “Security Architecture for the Internet Protocol,” November 1998.</span><span>)</span></a> [5] in tunnel mode. To save some header overhead it uses the encryption technices of <a class='info' href='#RFC3711'>SRTP<span> (</span><span class='info'>Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, “The Secure Real-time Transport Protocol (SRTP),” March 2004.</span><span>)</span></a> [1]. It supports peer to peer tunnels, where tunnel endpoints can be any combination of unicast, multicast or anycast hosts, so it defines a <a class='info' href='#RFC1546'>Host Anycast Service<span> (</span><span class='info'>Partridge, C., Mendez, T., and W. Milliken, “Host Anycasting Service,” November 1993.</span><span>)</span></a> [6] </p> <a name="anchor2"></a><br /><hr /> <a name="rfc.section.1.1"></a><h3>1.1. @@ -251,7 +251,7 @@ tunneling from unicast hosts to anycast networks</h3> </pre></div><table border="0" cellpadding="0" cellspacing="2" align="center"><tr><td align="center"><font face="monaco, MS Sans Serif" size="1"><b> Figure 2 </b></font><br /></td></tr></table><hr class="insert" /> -<p> +<p>When the unicast hosts wants to transmit data to one of the anycast DNS servers, it encapsulates the data and sends a SATP packet to the anycast address of the routers. The packet arrives at one of the routers, gets decapsulated and routed to the DNS server. This method can be used to tunnel between a clients and networks providing anycast services. It can also be used the other way to virtually locate a unicast service within anycasted networks. </p> <a name="anchor7"></a><br /><hr /> <a name="rfc.section.2.1.3"></a><h3>2.1.3. @@ -280,10 +280,10 @@ redundant tunnel connection of 2 networks</h3> <a name="rfc.section.2.2"></a><h3>2.2. Encapsulation</h3> -<p>SATP does not depend on which lower layer protocols is used, but it's most likely used on top of IP or UDP. This section should only discuss some issues on IP and UDP in combination with anycasting and tunnels. +<p>SATP does not depend on which lower layer protocols is used, but this section gives an example of how packets could look like. </p><br /><hr class="insert" /> -<a name="transtort_udp"></a> +<a name="transport_udp"></a> <p>Examples of SATP used with different lower layer and payload protocols </p><div style='display: table; width: 0; margin-left: 3em; margin-right: auto'><pre> @@ -320,8 +320,6 @@ Tunneling of Ethernet over IPv6 Tunneling of IPv6 over IPv4 with RTP payload </pre></div><table border="0" cellpadding="0" cellspacing="2" align="center"><tr><td align="center"><font face="monaco, MS Sans Serif" size="1"><b> Figure 4 </b></font><br /></td></tr></table><hr class="insert" /> -<p>When using UDP no flow control or retransmission is done, neither by UDP nor anytun. The encapsulated protocol HAS TO take care of this tasks if needed. UDP however has a checksum of the complete UDP datagram, so a packet gets discarded if there is a biterror in the payload -</p> <a name="anchor9"></a><br /><hr /> <a name="rfc.section.3"></a><h3>3. Using SATP on top of IP</h3> @@ -331,14 +329,22 @@ Using SATP on top of IP</h3> Fragmentation</h3> <p> - The only way of fully supporting fragmentation would be to synchronise fragments between all anycast servers. This is considered to be too much overhead, so there are two non perfect solutions for these problems. Either fragmentation HAS TO be disabled or if not all fragments arrive at the same server the ip datagramm HAS TO be discarded. As routing changes are not expected to occure very frequently, the encapsulated protocol can do a retransmission and all fragments will arrive at the new server. + The only way of fully supporting fragmentation would be to synchronise fragments between all anycast servers. This is considered to be too much overhead, so there are two non perfect solutions for these problems. Either fragmentation HAS TO be disabled or if not all fragments arrive at the same server the ip datagramm HAS TO be discarded. As routing changes are not expected to occure very frequently, the encapsulated protocol can do a retransmission and all fragments will arrive at the new server. </p> +<p>If the payload ip headers's Don't Fragment (DF) bit is set, than the DF bit of the outer ip header HAS TO be set as well. +</p> <a name="anchor11"></a><br /><hr /> +<a name="rfc.section.3.2"></a><h3>3.2. +ICMP messages</h3> + +<p>ICMP messages MUST be relayed according to <a class='info' href='#RFC2003'>rfc2003 section 4<span> (</span><span class='info'>Perkins, C., “IP Encapsulation within IP,” October 1996.</span><span>)</span></a> [3]. This is needed for path MTU discover +</p> +<a name="anchor12"></a><br /><hr /> <a name="rfc.section.4"></a><h3>4. Protocol specification</h3> -<a name="anchor12"></a><br /><hr /> +<a name="anchor13"></a><br /><hr /> <a name="rfc.section.4.1"></a><h3>4.1. Header format</h3> <br /><hr class="insert" /> @@ -367,25 +373,25 @@ Header format</h3> <p> </p> -<a name="anchor13"></a><br /><hr /> +<a name="anchor14"></a><br /><hr /> <a name="rfc.section.4.2"></a><h3>4.2. sender ID</h3> <p>The sender ID is a 16bit unsigned integer. It HAS TO be unique for every sender sharing the same anycast address </p> -<a name="anchor14"></a><br /><hr /> +<a name="anchor15"></a><br /><hr /> <a name="rfc.section.4.3"></a><h3>4.3. sequence number</h3> <p>The sequence number is a 32 bit unsigned integer in network byte order. It starts with a random value and is increased by 1 for every sent packet. After the maximum value, it starts over from 0. This overrun causes the ROC to be increased. </p> -<a name="anchor15"></a><br /><hr /> +<a name="anchor16"></a><br /><hr /> <a name="rfc.section.4.4"></a><h3>4.4. payload</h3> <p>A packet of the type payload type (e.g. an IP packet). </p> -<a name="anchor16"></a><br /><hr /> +<a name="anchor17"></a><br /><hr /> <a name="rfc.section.4.5"></a><h3>4.5. padding (OPTIONAL)</h3> @@ -393,13 +399,13 @@ padding (OPTIONAL)</h3> None of the pre-defined encryption transforms uses any padding; for these, the plaintext and encrypted payload sizes match exactly. Transforms are based on transforms of the SRTP protocol and these transforms might use the RTP padding format, so a RTP like padding is supported. If padding field is present, than the padding count field MUST be set to the padding lenght. </p> -<a name="anchor17"></a><br /><hr /> +<a name="anchor18"></a><br /><hr /> <a name="rfc.section.4.6"></a><h3>4.6. padding count</h3> <p>The number of octets of the padding field. This field is optional. It's presence is signaled by the key management and not by this protocol. If this field isn't present, the padding field MUST NOT be present as well. </p> -<a name="anchor18"></a><br /><hr /> +<a name="anchor19"></a><br /><hr /> <a name="rfc.section.4.7"></a><h3>4.7. payload type field</h3> @@ -420,19 +426,19 @@ HEX -<a name="anchor19"></a><br /><hr /> +<a name="anchor20"></a><br /><hr /> <a name="rfc.section.4.8"></a><h3>4.8. Encryption</h3> <p>Encryption is done in the same way as for <a class='info' href='#RFC3711'>SRTP<span> (</span><span class='info'>Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, “The Secure Real-time Transport Protocol (SRTP),” March 2004.</span><span>)</span></a> [1]. This section will only discuss some small changes that HAVE TO be made. Please read <a class='info' href='#RFC3711'>SRTP RFC3711 section 3-9<span> (</span><span class='info'>Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, “The Secure Real-time Transport Protocol (SRTP),” March 2004.</span><span>)</span></a> [1] for details. SSRC is replaced by the sender ID </p> -<a name="anchor20"></a><br /><hr /> +<a name="anchor21"></a><br /><hr /> <a name="rfc.section.5"></a><h3>5. Security Considerations</h3> <p>As satp uses the same encrytion technics as <a class='info' href='#RFC3711'>SRTP<span> (</span><span class='info'>Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, “The Secure Real-time Transport Protocol (SRTP),” March 2004.</span><span>)</span></a> [1], it shares the same security issues. This section will only discuss some small changes. Please read <a class='info' href='#RFC3711'>SRTP RFC3711 section 9<span> (</span><span class='info'>Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, “The Secure Real-time Transport Protocol (SRTP),” March 2004.</span><span>)</span></a> [1] for details. </p> -<a name="anchor21"></a><br /><hr /> +<a name="anchor22"></a><br /><hr /> <a name="rfc.section.5.1"></a><h3>5.1. Replay protection</h3> @@ -449,16 +455,18 @@ References</h3> <td class="author-text">Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, “<a href="ftp://ftp.isi.edu/in-notes/rfc3711.txt">The Secure Real-time Transport Protocol (SRTP)</a>,” RFC 3711, March 2004.</td></tr> <tr><td class="author-text" valign="top"><a name="RFC2119">[2]</a></td> <td class="author-text"><a href="mailto:sob@harvard.edu">Bradner, S.</a>, “<a href="ftp://ftp.isi.edu/in-notes/rfc2119.txt">Key words for use in RFCs to Indicate Requirement Levels</a>,” BCP 14, RFC 2119, March 1997 (<a href="ftp://ftp.isi.edu/in-notes/rfc2119.txt">TXT</a>, <a href="http://xml.resource.org/public/rfc/html/rfc2119.html">HTML</a>, <a href="http://xml.resource.org/public/rfc/xml/rfc2119.xml">XML</a>).</td></tr> +<tr><td class="author-text" valign="top"><a name="RFC2003">[3]</a></td> +<td class="author-text"><a href="mailto:perk@watson.ibm.com">Perkins, C.</a>, “<a href="ftp://ftp.isi.edu/in-notes/rfc2003.txt">IP Encapsulation within IP</a>,” RFC 2003, October 1996 (<a href="ftp://ftp.isi.edu/in-notes/rfc2003.txt">TXT</a>, <a href="http://xml.resource.org/public/rfc/html/rfc2003.html">HTML</a>, <a href="http://xml.resource.org/public/rfc/xml/rfc2003.xml">XML</a>).</td></tr> </table> <a name="rfc.references2"></a><br /><hr /> <h3>6.2. Informational References</h3> <table width="99%" border="0"> -<tr><td class="author-text" valign="top"><a name="RFC2784">[3]</a></td> +<tr><td class="author-text" valign="top"><a name="RFC2784">[4]</a></td> <td class="author-text"><a href="mailto:dino@procket.com">Farinacci, D.</a>, <a href="mailto:tony1@home.net">Li, T.</a>, <a href="mailto:stan_hanks@enron.net">Hanks, S.</a>, <a href="mailto:dmm@cisco.com">Meyer, D.</a>, and <a href="mailto:pst@juniper.net">P. Traina</a>, “<a href="ftp://ftp.isi.edu/in-notes/rfc2784.txt">Generic Routing Encapsulation (GRE)</a>,” RFC 2784, March 2000.</td></tr> -<tr><td class="author-text" valign="top"><a name="RFC2401">[4]</a></td> +<tr><td class="author-text" valign="top"><a name="RFC2401">[5]</a></td> <td class="author-text"><a href="mailto:kent@bbn.com">Kent, S.</a> and <a href="mailto:rja@corp.home.net">R. Atkinson</a>, “<a href="ftp://ftp.isi.edu/in-notes/rfc2401.txt">Security Architecture for the Internet Protocol</a>,” RFC 2401, November 1998 (<a href="ftp://ftp.isi.edu/in-notes/rfc2401.txt">TXT</a>, <a href="http://xml.resource.org/public/rfc/html/rfc2401.html">HTML</a>, <a href="http://xml.resource.org/public/rfc/xml/rfc2401.xml">XML</a>).</td></tr> -<tr><td class="author-text" valign="top"><a name="RFC1546">[5]</a></td> +<tr><td class="author-text" valign="top"><a name="RFC1546">[6]</a></td> <td class="author-text"><a href="mailto:craig@bbn.com">Partridge, C.</a>, <a href="mailto:tmendez@bbn.com">Mendez, T.</a>, and <a href="mailto:milliken@bbn.com">W. Milliken</a>, “<a href="ftp://ftp.isi.edu/in-notes/rfc1546.txt">Host Anycasting Service</a>,” RFC 1546, November 1993.</td></tr> </table> diff --git a/internet-draft-satp.txt b/internet-draft-satp.txt index 4292da6..88fd5eb 100644 --- a/internet-draft-satp.txt +++ b/internet-draft-satp.txt @@ -116,11 +116,11 @@ Internet-Draft secure anycast tunneling protocol (satp) March 2007 1. Introduction SATP is somehow a mixture of a generic encapsulation protocol like - GRE [3] and a secure tunneling protocol as IPsec [4] in tunnel mode. + GRE [4] and a secure tunneling protocol as IPsec [5] in tunnel mode. To save some header overhead it uses the encryption technices of SRTP [1]. It supports peer to peer tunnels, where tunnel endpoints can be any combination of unicast, multicast or anycast hosts, so it defines - a Host Anycast Service [5] + a Host Anycast Service [6] 1.1. Notational Conventions @@ -249,6 +249,14 @@ Internet-Draft secure anycast tunneling protocol (satp) March 2007 Figure 2 + When the unicast hosts wants to transmit data to one of the anycast + DNS servers, it encapsulates the data and sends a SATP packet to the + anycast address of the routers. The packet arrives at one of the + routers, gets decapsulated and routed to the DNS server. This method + can be used to tunnel between a clients and networks providing + anycast services. It can also be used the other way to virtually + locate a unicast service within anycasted networks. + 2.1.3. redundant tunnel connection of 2 networks An example of SATP used to connect 2 networks @@ -265,14 +273,6 @@ Internet-Draft secure anycast tunneling protocol (satp) March 2007 |de/encapsulated| path |de/encapsulated| - Figure 3 - - Network A has multiple routers, that act as gateway/tunnel endpoints - to another network B. This is done to build a redundant encrypted - tunnel connection between the two networks. All tunnel endpoints of - network A share the same anycast address and all tunnel endpoints of - network B share another anycast address. When a packet from network - A gets transmitted to network B, it first arrives on one of network @@ -281,6 +281,14 @@ Gsenger Expires September 2, 2007 [Page 5] Internet-Draft secure anycast tunneling protocol (satp) March 2007 + Figure 3 + + Network A has multiple routers, that act as gateway/tunnel endpoints + to another network B. This is done to build a redundant encrypted + tunnel connection between the two networks. All tunnel endpoints of + network A share the same anycast address and all tunnel endpoints of + network B share another anycast address. When a packet from network + A gets transmitted to network B, it first arrives on one of network A's border routers. Which router is used is determined by network A's internal routing. This router encapsulates the package and sends it to the anycast address of the network B routers. The SATP packet @@ -289,61 +297,23 @@ Internet-Draft secure anycast tunneling protocol (satp) March 2007 2.2. Encapsulation - SATP does not depend on which lower layer protocols is used, but it's - most likely used on top of IP or UDP. This section should only - discuss some issues on IP and UDP in combination with anycasting and - tunnels. + SATP does not depend on which lower layer protocols is used, but this + section gives an example of how packets could look like. - Examples of SATP used with different lower layer and payload - protocols - +------+-----+-------------------------------+ - | | | + ---------------+------ | - | IPv6 | UDP | SATP | Ethernet 802.3 | ... | | - | | | +----------------+-----+ | - +------+-----+-------------------------------+ - Tunneling of Ethernet over UDP/IPv6 - +------+-----+---------------------------+ - | | | +------+-----+-----+ | - | IPv4 | UDP | SATP | IPv6 | UDP | RTP | | - | | | +------+-----+-----+ | - +------+-----+---------------------------+ - Tunneling of IPv6 over UDP/IPv4 with RTP payload - +------+-------------------------------+ - | | + ---------------+------ | - | IPv6 | SATP | Ethernet 802.3 | ... | | - | | +----------------+-----+ | - +------+-------------------------------+ - Tunneling of Ethernet over IPv6 - +------+---------------------------+ - | | +------+-----+-----+ | - | IPv4 | SATP | IPv6 | UDP | RTP | | - | | +------+-----+-----+ | - +------+---------------------------+ - Tunneling of IPv6 over IPv4 with RTP payload -Gsenger Expires September 2, 2007 [Page 6] - -Internet-Draft secure anycast tunneling protocol (satp) March 2007 - - Figure 4 - When using UDP no flow control or retransmission is done, neither by - UDP nor anytun. The encapsulated protocol HAS TO take care of this - tasks if needed. UDP however has a checksum of the complete UDP - datagram, so a packet gets discarded if there is a biterror in the - payload @@ -362,17 +332,47 @@ Internet-Draft secure anycast tunneling protocol (satp) March 2007 +Gsenger Expires September 2, 2007 [Page 6] + +Internet-Draft secure anycast tunneling protocol (satp) March 2007 + Examples of SATP used with different lower layer and payload + protocols + +------+-----+-------------------------------+ + | | | + ---------------+------ | + | IPv6 | UDP | SATP | Ethernet 802.3 | ... | | + | | | +----------------+-----+ | + +------+-----+-------------------------------+ + Tunneling of Ethernet over UDP/IPv6 + +------+-----+---------------------------+ + | | | +------+-----+-----+ | + | IPv4 | UDP | SATP | IPv6 | UDP | RTP | | + | | | +------+-----+-----+ | + +------+-----+---------------------------+ + Tunneling of IPv6 over UDP/IPv4 with RTP payload + +------+-------------------------------+ + | | + ---------------+------ | + | IPv6 | SATP | Ethernet 802.3 | ... | | + | | +----------------+-----+ | + +------+-------------------------------+ + Tunneling of Ethernet over IPv6 + +------+---------------------------+ + | | +------+-----+-----+ | + | IPv4 | SATP | IPv6 | UDP | RTP | | + | | +------+-----+-----+ | + +------+---------------------------+ + Tunneling of IPv6 over IPv4 with RTP payload + Figure 4 @@ -406,13 +406,13 @@ Internet-Draft secure anycast tunneling protocol (satp) March 2007 to occure very frequently, the encapsulated protocol can do a retransmission and all fragments will arrive at the new server. + If the payload ip headers's Don't Fragment (DF) bit is set, than the + DF bit of the outer ip header HAS TO be set as well. +3.2. ICMP messages - - - - - + ICMP messages MUST be relayed according to rfc2003 section 4 [3]. + This is needed for path MTU discover @@ -519,7 +519,7 @@ Internet-Draft secure anycast tunneling protocol (satp) March 2007 4.7. payload type field The payload type field defines the payload protocol. ETHER TYPE - protocol numbers are used. See IANA assigned ethernet numbers [6] . + protocol numbers are used. See IANA assigned ethernet numbers [7] . The values 0000-05DC are reserverd and MUST NOT be used. Some examples for protocol types @@ -628,15 +628,18 @@ Internet-Draft secure anycast tunneling protocol (satp) March 2007 [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. + [3] Perkins, C., "IP Encapsulation within IP", RFC 2003, + October 1996. + 6.2. Informational References - [3] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. Traina, + [4] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, March 2000. - [4] Kent, S. and R. Atkinson, "Security Architecture for the + [5] Kent, S. and R. Atkinson, "Security Architecture for the Internet Protocol", RFC 2401, November 1998. - [5] Partridge, C., Mendez, T., and W. Milliken, "Host Anycasting + [6] Partridge, C., Mendez, T., and W. Milliken, "Host Anycasting Service", RFC 1546, November 1993. @@ -665,9 +668,6 @@ Internet-Draft secure anycast tunneling protocol (satp) March 2007 - - - Gsenger Expires September 2, 2007 [Page 12] Internet-Draft secure anycast tunneling protocol (satp) March 2007 @@ -675,7 +675,7 @@ Internet-Draft secure anycast tunneling protocol (satp) March 2007 URIs - [6] <http://www.iana.org/assignments/ethernet-numbers> + [7] <http://www.iana.org/assignments/ethernet-numbers> diff --git a/internet-draft-satp.xml b/internet-draft-satp.xml index db3a229..75a6e5c 100644 --- a/internet-draft-satp.xml +++ b/internet-draft-satp.xml @@ -7,6 +7,7 @@ <!ENTITY rfc2784 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.2784.xml'> <!ENTITY rfc2401 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.2401.xml'> <!ENTITY rfc2119 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml'> + <!ENTITY rfc2003 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.2003.xml'> ]> <rfc ipr='full3978' docName='draft-gsenger-secure-anycast-tunneling-protocol-00'> <front> @@ -97,7 +98,7 @@ </artwork> </figure> - <t></t> + <t>When the unicast hosts wants to transmit data to one of the anycast DNS servers, it encapsulates the data and sends a SATP packet to the anycast address of the routers. The packet arrives at one of the routers, gets decapsulated and routed to the DNS server. This method can be used to tunnel between a clients and networks providing anycast services. It can also be used the other way to virtually locate a unicast service within anycasted networks.</t> </section> <section title='redundant tunnel connection of 2 networks'> <figure anchor="connect_networks"> @@ -121,9 +122,9 @@ </section> </section> <section title="Encapsulation"> - <t>SATP does not depend on which lower layer protocols is used, but it's most likely used on top of IP or UDP. This section should only discuss some issues on IP and UDP in combination with anycasting and tunnels. + <t>SATP does not depend on which lower layer protocols is used, but this section gives an example of how packets could look like. </t> - <figure anchor="transtort_udp"> + <figure anchor="transport_udp"> <preamble>Examples of SATP used with different lower layer and payload protocols</preamble> <artwork> +------+-----+-------------------------------+ @@ -159,15 +160,17 @@ Tunneling of Ethernet over IPv6 Tunneling of IPv6 over IPv4 with RTP payload </artwork> </figure> - <t>When using UDP no flow control or retransmission is done, neither by UDP nor anytun. The encapsulated protocol HAS TO take care of this tasks if needed. UDP however has a checksum of the complete UDP datagram, so a packet gets discarded if there is a biterror in the payload</t> </section> </section> <section title="Using SATP on top of IP"> <section title="Fragmentation"> <t> - The only way of fully supporting fragmentation would be to synchronise fragments between all anycast servers. This is considered to be too much overhead, so there are two non perfect solutions for these problems. Either fragmentation HAS TO be disabled or if not all fragments arrive at the same server the ip datagramm HAS TO be discarded. As routing changes are not expected to occure very frequently, the encapsulated protocol can do a retransmission and all fragments will arrive at the new server. - </t> + The only way of fully supporting fragmentation would be to synchronise fragments between all anycast servers. This is considered to be too much overhead, so there are two non perfect solutions for these problems. Either fragmentation HAS TO be disabled or if not all fragments arrive at the same server the ip datagramm HAS TO be discarded. As routing changes are not expected to occure very frequently, the encapsulated protocol can do a retransmission and all fragments will arrive at the new server. + </t><t>If the payload ip headers's Don't Fragment (DF) bit is set, than the DF bit of the outer ip header HAS TO be set as well.</t> </section> + <section title="ICMP messages"> + <t>ICMP messages MUST be relayed according to <xref target="RFC2003">rfc2003 section 4</xref>. This is needed for path MTU discover</t> + </section> </section> <section title="Protocol specification"> <section title="Header format"> @@ -243,6 +246,7 @@ HEX <references title="Normative References"> &rfc3711; &rfc2119; + &rfc2003; </references> <references title="Informational References"> &rfc2784; |