draft-ietf-dhc-relay-port-09.txt   draft-ietf-dhc-relay-port-10.txt 
Networking Working Group N. Shen Networking Working Group N. Shen
Internet-Draft E. Chen Internet-Draft E. Chen
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: June 2, 2018 November 29, 2017 Expires: June 17, 2018 December 14, 2017
Generalized UDP Source Port for DHCP Relay Generalized UDP Source Port for DHCP Relay
draft-ietf-dhc-relay-port-09 draft-ietf-dhc-relay-port-10
Abstract Abstract
This document proposes an extension to the DHCP protocols that allows This document proposes an extension to the DHCP protocols that allows
a relay agent to use any available source port for upstream a relay agent to use any available source port for upstream
communications, and to include a DHCP option that can be used to communications, and to include a DHCP option that can be used to
statelessly route responses back to the appropriate source port on statelessly route responses back to the appropriate source port on
downstream communications. downstream communications.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 2, 2018. This Internet-Draft will expire on June 17, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3.1. Additions to DHCPv4 in RFC 2131 3.1. Additions to DHCPv4 in RFC 2131
Section 4.1 of RFC 2131 [RFC2131] specifies that: Section 4.1 of RFC 2131 [RFC2131] specifies that:
DHCP uses UDP as its transport protocol. DHCP messages from a DHCP uses UDP as its transport protocol. DHCP messages from a
client to a server are sent to the 'DHCP server' port (67), and client to a server are sent to the 'DHCP server' port (67), and
DHCP messages from a server to a client are sent to the 'DHCP DHCP messages from a server to a client are sent to the 'DHCP
client' port (68). client' port (68).
Relay agents implementing this specification may be configured Relay agents implementing this specification may be configured
instead to use a source port number other than 67, and to receive instead to use a source port number other than 67 when relaying
responses on that same port. This will only work when the DHCP messages toward servers, and to receive responses toward clients on
server or relay agent to which such a relay agent is forwarding that same port. This will only work when the DHCP server or relay
messages is upgraded to support this extension. agent to which such a relay agent is forwarding messages is upgraded
to support this extension.
3.2. Additions to DHCPv6 in RFC 3315 3.2. Additions to DHCPv6 in RFC 3315
Section 5.2 of RFC 3315 [RFC3315] specifies that: Section 5.2 of RFC 3315 [RFC3315] specifies that:
Clients listen for DHCP messages on UDP port 546. Servers and Clients listen for DHCP messages on UDP port 546. Servers and
relay agents listen for DHCP messages on UDP port 547. relay agents listen for DHCP messages on UDP port 547.
Relay agents implementing this specification may be configured Relay agents implementing this specification may be configured
instead to use a source port number other than 547, and to receive instead to use a source port number other than 547 when relaying
responses on that same port. This will only work when the DHCP messages toward servers, and to receive responses toward clients on
server or relay agent to which such a relay agent is forwarding that same port. This will only work when the DHCP server or relay
messages is upgraded to support this extension. agent to which such a relay agent is forwarding messages is upgraded
to support this extension.
4. Relay Source Port Sub-option and Option 4. Relay Source Port Sub-option and Option
Relay agents do not maintain state. To return a message to its Relay agents do not maintain state. To return a message to its
source, the relay agent must include all the required information in source, the relay agent must include all the required information in
the Relay-Forward message. When a relay in a sequence of cascaded the Relay-Forward message. When a relay in a sequence of cascaded
relays does not use the standard source port, that source port must relays does not use the standard source port, that source port must
be included along with the source address. This option allows the be included along with the source address. This option allows the
relay agent to do so. relay agent to do so.
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message. When DHCP server sends the DHCP Relay-reply to Relay3, message. When DHCP server sends the DHCP Relay-reply to Relay3,
Relay3 finds its own relay option has this "Downstream Source Port" Relay3 finds its own relay option has this "Downstream Source Port"
with the value of 2000. Relay3 will use this UDP port when sending with the value of 2000. Relay3 will use this UDP port when sending
the Relay-reply message to Relay2. Relay2 finds its own relay option the Relay-reply message to Relay2. Relay2 finds its own relay option
also has this "Downstream Source Port" with the value of 1000. also has this "Downstream Source Port" with the value of 1000.
Relay2 will use this UDP port when sending the Relay-reply message to Relay2 will use this UDP port when sending the Relay-reply message to
Relay1. Relay1.
7. IANA Considerations 7. IANA Considerations
A new sub-option, DHCPv4 Relay Source Port, is defined in this A new sub-option, DHCPv4 Relay Source Port Sub-Option, is defined in
document within the IPv4 Relay Agent Information Option. It needs to this document within the IPv4 Relay Agent Information Option. It
be assigned by IANA in the "DHCP Relay Agent Sub-Option Codes" needs to be assigned by IANA in the "DHCP Relay Agent Sub-Option
registry, http://www.iana.org/assignments/bootp-dhcp-parameters as Codes" registry, http://www.iana.org/assignments/bootp-dhcp-
specified in [RFC3046]. parameters as specified in [RFC3046].
A new option, DHCPv6 Relay Source Port, is defined in this document A new option, DHCPv6 Relay Source Port, is defined in this document
for DHCPv6 and it needs to be assigned by IANA for the DHCPv6 option for DHCPv6 and it needs to be assigned by IANA for the DHCPv6 option
code, in the "Option Codes" registry for DHCPv6, code, in the "Option Codes" registry for DHCPv6,
http://www.iana.org/assignments/dhcpv6-parameters as specified in http://www.iana.org/assignments/dhcpv6-parameters as specified in
[RFC3315]. [RFC3315].
8. Security Considerations 8. Security Considerations
[RFC3118] and [RFC3315] described many of the threats in using DHCP. [RFC3118] and [RFC3315] described many of the threats in using DHCP.
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