extension of dhcp leasequery in bridging/switching networks draft-joshi-dhc-lease-query-ext-02.txt...
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![Page 1: Extension of DHCP LEASEQUERY in Bridging/Switching networks draft-joshi-dhc-lease-query-ext-02.txt DHC Working Group Bharat Joshi ( bharat_joshi@infosys.com](https://reader036.vdocuments.mx/reader036/viewer/2022082613/5697bfdf1a28abf838cb29bf/html5/thumbnails/1.jpg)
Extension of DHCP LEASEQUERY in Bridging/Switching networks
draft-joshi-dhc-lease-query-ext-02.txtDHC Working Group
Bharat Joshi ( [email protected] )
Pavan Kurapati ( [email protected] )
Infosys Technologies Ltd.
![Page 2: Extension of DHCP LEASEQUERY in Bridging/Switching networks draft-joshi-dhc-lease-query-ext-02.txt DHC Working Group Bharat Joshi ( bharat_joshi@infosys.com](https://reader036.vdocuments.mx/reader036/viewer/2022082613/5697bfdf1a28abf838cb29bf/html5/thumbnails/2.jpg)
RFC 4388 for Layer 3 Access Network
PC
ACCESS CONCENTRATOR IP DSLAM /BRASLocal Loop
STB
RG
PC
STB
RG
Service Provider’sIP Network
DHCP Server
• Add option 82 and “giaddr”• Layer 3 Relay Agent
• Forwards DHCP reply based on option 82• Extract information like MAC/IP/Lease time
• Generates DHCP Lease Query
• Avoid MAC/IP Spoofing
• Enhance Security by avoiding ARP generation
• Extracted information can be used to:
![Page 3: Extension of DHCP LEASEQUERY in Bridging/Switching networks draft-joshi-dhc-lease-query-ext-02.txt DHC Working Group Bharat Joshi ( bharat_joshi@infosys.com](https://reader036.vdocuments.mx/reader036/viewer/2022082613/5697bfdf1a28abf838cb29bf/html5/thumbnails/3.jpg)
Extension of RFC 4388 to Layer 2 Access Networks
Service Provider’sIP Network
DHCP Server
Local Loop
STB
RG
L3 Relay Agent
Ethernet Aggregation Switch
Access ConcentratorL2 Relay Agent
• Adds option 82
• Add “giaddr”
• Extracts information like MAC/IP/Lease time
• Forwards reply based on “giaddr” [Destination IP in DHCP reply]
• Forwards reply based on option 82
• Avoid MAC/IP Spoofing
• Avoid Unknown MAC Flooding
• Generates Lease Query
Local Loop
STB
RG
• Extracted information can be used to:
![Page 4: Extension of DHCP LEASEQUERY in Bridging/Switching networks draft-joshi-dhc-lease-query-ext-02.txt DHC Working Group Bharat Joshi ( bharat_joshi@infosys.com](https://reader036.vdocuments.mx/reader036/viewer/2022082613/5697bfdf1a28abf838cb29bf/html5/thumbnails/4.jpg)
Changes from 00 to 02• New option for ‘Access Concentrator’ hardware address.
• Added text for:
– Layer 3 Relay Agent MUST NOT add option 82 to DHCPLEASEQUERY messages.
– DHCP server MUST add the new option only in the reply of DHCPLEASEQUERY messages.
– Handling multiple responses received for a DHCPLEASEQUERY message
– If a Layer 2 Relay Agent can use its management IP address to talk to DHCP server than that should be preferred.
– Added authentication details of DHCP LEASEQUERY messages as per RFC 3118 in security section.
– Removed the restriction of mandating the insertion of new option at the end
– Some minor comments and grammatical issues.
![Page 5: Extension of DHCP LEASEQUERY in Bridging/Switching networks draft-joshi-dhc-lease-query-ext-02.txt DHC Working Group Bharat Joshi ( bharat_joshi@infosys.com](https://reader036.vdocuments.mx/reader036/viewer/2022082613/5697bfdf1a28abf838cb29bf/html5/thumbnails/5.jpg)
Next Step
• PoC implementation is done and verified.
• More review in WG mailing list.
• Working group item?
![Page 6: Extension of DHCP LEASEQUERY in Bridging/Switching networks draft-joshi-dhc-lease-query-ext-02.txt DHC Working Group Bharat Joshi ( bharat_joshi@infosys.com](https://reader036.vdocuments.mx/reader036/viewer/2022082613/5697bfdf1a28abf838cb29bf/html5/thumbnails/6.jpg)
Unicast Address Sub-Option draft-decnodder-dhc-rai-unicast-01.txt
DHC Working Group
Stefaan De Cnodder
Alcatel
Pavan Kurapati
Infosys Technologies Ltd.
![Page 7: Extension of DHCP LEASEQUERY in Bridging/Switching networks draft-joshi-dhc-lease-query-ext-02.txt DHC Working Group Bharat Joshi ( bharat_joshi@infosys.com](https://reader036.vdocuments.mx/reader036/viewer/2022082613/5697bfdf1a28abf838cb29bf/html5/thumbnails/7.jpg)
Need for unicast-address sub-option
• DHCP replies are broadcast/flooded to L2 RA under below
conditions :
– If client sets Broadcast flag in DHCP requests
– If L2 RA does MAC translation, Ethernet aggregation devices
does not learn client’s MAC address. Hence even if broadcast flag
is not set, replies are flooded to all the L2 RAs.
• Flooding need to be avoided between L2 RA and L3 RA
![Page 8: Extension of DHCP LEASEQUERY in Bridging/Switching networks draft-joshi-dhc-lease-query-ext-02.txt DHC Working Group Bharat Joshi ( bharat_joshi@infosys.com](https://reader036.vdocuments.mx/reader036/viewer/2022082613/5697bfdf1a28abf838cb29bf/html5/thumbnails/8.jpg)
New sub-option in Option-82
• New sub-option called ‘unicast-address’ is defined for Relay agent option.
• L2 RA fills unicast-address sub-option with:
– ‘chaddr’ if L2 RA is acting as a bridge without MAC translation
– The hardware address which is used for translation (eg, ACs MAC address) if L2 RA does MAC translation.
.
![Page 9: Extension of DHCP LEASEQUERY in Bridging/Switching networks draft-joshi-dhc-lease-query-ext-02.txt DHC Working Group Bharat Joshi ( bharat_joshi@infosys.com](https://reader036.vdocuments.mx/reader036/viewer/2022082613/5697bfdf1a28abf838cb29bf/html5/thumbnails/9.jpg)
Processing of new sub-option
• DHCP server MUST echo this sub-option as it is in option-82
• L3 RA should look for this new sub-option and if present use this MAC address to forward the DHCP messages irrespective of the broadcast flag.
• L2 RA should respect the broadcast flag and should change the destination MAC address accordingly. i.e
– If broadcast flag is set, change the destination MAC as broadcast
– If broadcast flag is not set, change the destination MAC to that of ‘chaddr’
![Page 10: Extension of DHCP LEASEQUERY in Bridging/Switching networks draft-joshi-dhc-lease-query-ext-02.txt DHC Working Group Bharat Joshi ( bharat_joshi@infosys.com](https://reader036.vdocuments.mx/reader036/viewer/2022082613/5697bfdf1a28abf838cb29bf/html5/thumbnails/10.jpg)
Next Step
• More review in WG mailing list.
• Working group item?