Information Option Stacking - - PowerPoint PPT Presentation

Relay Agent Information Option Stacking

(draft-zheng-dhc-relay-agent-stacking-00) Robin Zheng IETF 76 - DHC

Outline

• Objective
• Problem Definition
• Scenario
• Proposed Solution

Objective

• This contribution proposes to allow adding

a “second” relay agent information option (Option 82) to a DHCP message which already has a relay agent information

• ption

Problem Definition

• RFC3046

– DHCP Relay Agent does NOT add a "second" Relay Agent Information option, when it receives a DHCP packet with a Relay Agent Information option already present from a trusted circuit

• However, there are at lease two scenarios where

there are multiple relay agents between DHCP client and server. Each relay agent has to add its relay agent information.

– Scenario 1--Cascaded LAN access – Scenario 2--PON FTTC/B

Scenario 1--Cascaded LAN access

user1 user2 user3 user4 user5 user6 DHCP server Aggregation network Floor switch Floor switch Curb switch F-switch-identifier eth slot/port[:vlan- id] C-switch-identifier eth frame/slot/port [:vlan-id] DHCP packet

• This is a scenario which had been discussed in IETF 75th

meeting.

• As the problem is described in “draft-huang-dhc-relay-ps-00 ”, the

amount of configuration information will substantially increase if

• nly Floor switches allow to add option 82.

Scenario 2--PON FTTC/B

ONU user1 ONU user2 user3 user4 user5 user6 splitter OLT BNG AAA server DHCP server Layer 2 network ONU-identifier eth/ atm slot/port[:vlan-id] OLT-identifier eth/ atm slot/port [:vlan-id] DHCP packet

• In order to locate a user precisely from a DHCP message

via Option 82, ONU need add a user's access loop identification on which port the user is attached, while OLT need add PON port where the ONU is attached.

• DHCP Relay Agent resides in both ONU and OLT

Proposed Solution

DHCP option Multiple option 82 in the end of option field

• Agent Operation

– The relay agent can add a “second” relay agent information option (Option 82) to a DHCP message which already has a relay agent

• ption

– The “second” relay agent information option shall be added as the last option (but before ‘End Option’ 255) – The “second” relay agent information option echoed by a server MUST be removed by the relay agent which added it when forwarding a server-to-client response back to the client

Question

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