DHCP Option 82

Notes on BT NGA FTTC Option 82 for sync speed, via Cablelinke

ip vrf dhcp-test

int gi0/21
 service instance 2222 ethernet
  description Test-Site
  encapsulation dot1q 2 second-dot1q 2222
  rewrite ingress tag pop 2 symmetric
  bridge-domain 2222


interface Vlan2222
 ip vrf forwarding dhcp-test
 ip address 192.168.58.254 255.255.255.0



ip dhcp relay information trust-all
ip dhcp bootp ignore


ip dhcp class dhcp-test
  relay agent information
     relay-information hex 020c01020304*

! relay-information hex  bitmask 0000000FF

ip dhcp pool dhcp-test
 vrf dhcp-test
 network 192.168.58.0 255.255.255.0
 class dhcp-test
  address range 192.168.58.1 192.168.58.10



Feb 16 2015 15:26:08.743 UTC: DHCPD: Reload workspace interface Vlan2222 tableid 15.
Feb 16 2015 15:26:08.743 UTC: DHCPD: tableid for 192.168.58.254 on Vlan2222 is 15
Feb 16 2015 15:26:08.743 UTC: DHCPD: client's VPN is dhcp-test.
Feb 16 2015 15:26:08.743 UTC: DHCPD: bad remote system id length (0 bytes).
Feb 16 2015 15:26:08.743 UTC: DHCPD: using received relay info.
Feb 16 2015 15:26:08.743 UTC: DHCPD: DHCPDISCOVER received from client 0063.6973.636f.2d31.3865.372e.3238.3034.2e38.6434.302d.4769.302e.3232.3232 on interface Vlan2222.
Feb 16 2015 15:26:08.743 UTC: DHCPD: bad remote system id length (0 bytes).
Feb 16 2015 15:26:08.743 UTC: DHCPD: using received relay info.
Feb 16 2015 15:26:08.743 UTC: DHCPD: bad remote system id length (0 bytes).
Feb 16 2015 15:26:08.743 UTC: DHCPD: Class 'dhcp-test' matched by default
Feb 16 2015 15:26:08.743 UTC: DHCPD: Searching for a match to 'relay-information 01154e4d4247485a2065746820302f312f34323a3130310200091600000de9118104000007d0820400009c389003010200' in class dhcp-test
Feb 16 2015 15:26:08.743 UTC: DHCPD: bad remote system id length (0 bytes).



CPE details: 

0063.6973.636f.2d31.3865.372e.3238.3034.2e38.6434.302d.4769.302e.3232.3232

00x cisco-18e7.2804.8d40-Gi0.2222

vendor-mac.address-wanport





Option 82 Details:

01154e4d4247485a2065746820302f312f34323a3130310200091600000de9118104000007d0820400009c389003010200



01154e4d4247485a2065746820302f312f34323a313031

0x01 = circuit-id (rfc3046#section-3.0)
0x15 = Length of this value (21 in decimal)
value = 4e4d4247485a2065746820302f312f34323a313031 = BT DSLAM Details
value = "NMBGHZ eth 0/1/42:101"

value = "Access-Node-Identifier eth slot/port[:vlan-id]" (as per R-124 in TR-101 - Migration to Ethernet Based DSL Aggregation)



0200

0x02 = remote-id (rfc3046#section-3.0)
0x00 = Length



091600000de9118104000007d0820400009c389003010200

0x09 = Vendor specific option 92 sub-option details (TLVs)
0x16 = Length 22 in dec
value = 00000de9118104000007d0820400009c389003010200


00000de9 = 0x00 0x00 0x0d 0xe9 = 3561 in decimal, IANA vendor ID Broadband Forum / ADSL Forum
0x11 = Length of remaining vendor specific information (17 in decimal)



8104000007d0

0x81 = Upstream rate (BT SIN 498 v6 - Section 2.1.7 Intermediate Agent / DHCP Relay Agent)
0x04 = Length
value = 00 00 07 d0 = 2000Kbps



820400009c38

0x82 = Downstream rate (BT SIN 498 v6 - Section 2.1.7 Intermediate Agent / DHCP Relay Agent)
0x04 = Length
value = 00 00 9c 38 = 39992Kbps



9003010200

0x90 = Access Loop Encapsulation (BT SIN 498 v6 - Section 2.1.7 Intermediate Agent / DHCP Relay Agent)
0x03 = Length
value = 01 02 00 = Ethernet (0x01), enc type one = single VLAN tag (0x02), enc type two = none (0x00) (as per R-124 in TR-101 - Migration to Ethernet Based DSL Aggregation)



References:
https://tools.ietf.org/html/rfc3046
https://www.broadband-forum.org/technical/download/TR-101.pdf
http://www.sinet.bt.com/sinet/SINs/pdf/498v6p0.pdf
http://www.juniper.net/techpubs/en_US/junose14.3/topics/concept/dhcp-relay-option-82-suboptions-overview.html
http://www.iana.org/assignments/enterprise-numbers/enterprise-numbers
http://www.asciitohex.com/

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