تكوين Microsoft Windows Server 2016/2019 لتقديم خدمات DHCP لـ VXLAN (DFA)

To configure DHCP on Windows server. 

1. Create a super scope. Within the super scope, create scope B, S1, S2, S3, …, Sn for the subnet B and the subnets for each segment. 
2. In scope B,  specify the 'Exclusion Range' to be the entire address range (so that the offered address range must not be from this scope). 
3. For every segment scope Si, specify a policy that matches on Agent Circuit ID with value of '0108000600XXXXXX', where '0108000600' is a fixed value for all segments, the 6 numbers "XXXXXX" is the segment ID value in hexadecimal. Also ensure to check the Append wildcard(*) check box. 
4. Set the policy address range to the entire range of the scope.

• لماذا لا يتم دعم Microsoft Windows Server 2000/2003/2008؟
• ما سبب تعقيد التكوين في Microsoft Windows Server 2012؟
• ما مدى سهولة الإعداد في Microsoft Windows Server 2016/2019؟

المقدمة

كيف يتم تكوين ترحيل DHCP في مصنع VXLAN BGP EVPN، DFA

• دليل تهيئة Nexus 9000 VXLAN 7.X
• دليل تهيئة Nexus 9000 VXLAN 9.3
• DFA (Cisco Dynamic Fabric Automation)

service dhcp
ip dhcp relay
ip dhcp relay information option
ip dhcp relay information option vpn
interface loopback10
  vrf member VRF1
  ip address 10.120.0.1/32 tag 1234567
interface Vlan12
  no shutdown
  vrf member VRF1
  no ip redirects
  ip address 10.120.251.1/24 tag 1234567
  no ipv6 redirects
  fabric forwarding mode anycast-gateway
  ip dhcp relay address 10.0.0.5
  ip dhcp relay source-interface loopback10

تنفيذ طلبات RFC في تشغيل خدمة ترحيل DHCP في مصانع VXLAN BGP EVPN

• RFC, Nexus 9000 v9.3
• RFC, Nexus 9000 v7.x

•	Sub-option 151(0x97) - Virtual Subnet Selection (Defined in RFC#6607)
Used to convey VRF related information to the DHCP server in an MPLS-VPN and VXLAN EVPN multi-tenant environment.

•	Sub-option 11(0xb) - Server ID Override (Defined in RFC#5107.) 
The server identifier (server ID) override sub-option allows the DHCP relay agent to specify a new value for the server ID option, which is inserted by the DHCP server in the reply packet. This sub-option allows the DHCP relay agent to act as the actual DHCP server such that the renew requests will come to the relay agent rather than the DHCP server directly. The server ID override sub-option contains the incoming interface IP address, which is the IP address on the relay agent that is accessible from the client. Using this information, the DHCP client sends all renew and release request packets to the relay agent. The relay agent adds all of the appropriate sub-options and then forwards the renew and release request packets to the original DHCP server. For this function, Cisco’s proprietary implementation is sub-option 152(0x98). You can use the ip dhcp relay sub-option type cisco command to manage the function.

Sub-option 5(0x5) - Link Selection (Defined in RFC#3527.) 

The link selection sub-option provides a mechanism to separate the subnet/link on which the DHCP client resides from the gateway address (giaddr), which can be used to communicate with the relay agent by the DHCP server. The relay agent will set the sub-option to the correct subscriber subnet and the DHCP server will use that value to assign an IP address rather than the giaddr value. The relay agent will set the giaddr to its own IP address so that DHCP messages are able to be forwarded over the network. For this function, Cisco’s proprietary implementation is sub-option 150(0x96). You can use the ip dhcp relay sub-option type ciscocommand to manage the function.

Cisco DHCP Microsoft Windows Server 2012

If multiple DHCP Scopes are required for multiple subnets, you need to create one LoopbackX per subnet/vlan on all LEAFS and create a superscope with a loopbackX range scope and actual client IP subnet scope per vlan.

Create Superscope for all scopes you want to use for Option 82-based policies.
Note
The Superscope should combine all scopes and act as the administrative boundary.

Let us assume the switch is using the address from subnet B (it can be the backbone subnet, management subnet, or any customer designated subnet for this purpose) to communicate with the Windows DHCP server. In DFA we have subnets S1, S2, S3, …, Sn for segment s1, s2, s3, …, sn. 

To configure DHCP on Windows server. 

1. Create a super scope. Within the super scope, create scope B, S1, S2, S3, …, Sn for the subnet B and the subnets for each segment. 
2. In scope B,  specify the 'Exclusion Range' to be the entire address range (so that the offered address range must not be from this scope). 
3. For every segment scope Si, specify a policy that matches on Agent Circuit ID with value of '0108000600XXXXXX', where '0108000600' is a fixed value for all segments, the 6 numbers "XXXXXX" is the segment ID value in hexadecimal. Also ensure to check the Append wildcard(*) check box. 
4. Set the policy address range to the entire range of the scope.

DHCP على Microsoft Windows Server (النطاق الفائق والسياسة)

نطاق فائق

Superscope is an administrative feature of a DHCP server that can be used to group multiple scopes as a single administrative entity. Superscope allows a DHCP server to provide leases from more than one scope to clients on a single physical network. Scopes added to a superscope are called member scopes.

سياسات

The DHCP Server role in Windows Server 2012 introduces a new feature that allows you to create IPv4 policies that specify custom IP address and option assignments for DHCP clients based on a set of conditions.

The policy based assignment (PBA) feature allows you to group DHCP clients by specific attributes based on fields contained in the DHCP client request packet. PBA enables targeted administration and greater control of the configuration parameters delivered to network devices with DHCP.

الجزء الرئيسي

لماذا لا يتم دعم Microsoft Windows Server 2000/2003/2008؟

1. يتم إرسال طلب من العميل إلى Broadcast (DHCP Discover).
2. ترسل المعدات (Nexus) حزمة إلى خادم DHCP (اكتشاف DHCP + الخيار 82).
3. يقبل خادم DHCP الحزمة ويعالجها ويرسلها مرة أخرى ، ولكن بدون الخيار 82. (عرض DHCP - بدون الخيار 82)
4. تتلقى المعدات (Nexus) حزمة من خادم DHCP. (عرض DHCP) ولكن لا يرسل هذه الحزمة إلى المستخدم النهائي.

بيانات الشم - على Windows Server 2008 وعلى عميل DHCP

Windows Server 2008 . (Option 82 )

Windows Server 2008 . (Option 82 )

– DHCP Discover DHCP Offer

:

NEXUS-9000V-SW-1# show ip dhcp relay statistics 
----------------------------------------------------------------------
Message Type             Rx              Tx           Drops  
----------------------------------------------------------------------
Discover                  8               8               0
Offer                     8               8               0
Request(*)                0               0               0
Ack                       0               0               0
Release(*)                0               0               0
Decline                   0               0               0
Inform(*)                 0               0               0
Nack                      0               0               0
----------------------------------------------------------------------
Total                    16              16               0
----------------------------------------------------------------------

DHCP L3 FWD:
Total Packets Received                           :         0
Total Packets Forwarded                          :         0
Total Packets Dropped                            :         0
Non DHCP:
Total Packets Received                           :         0
Total Packets Forwarded                          :         0
Total Packets Dropped                            :         0
DROP:
DHCP Relay not enabled                           :         0
Invalid DHCP message type                        :         0
Interface error                                  :         0
Tx failure towards server                        :         0
Tx failure towards client                        :         0
Unknown output interface                         :         0
Unknown vrf or interface for server              :         0
Max hops exceeded                                :         0
Option 82 validation failed                      :         0
Packet Malformed                                 :         0
Relay Trusted port not configured                :         0
DHCP Request dropped on MCT                      :         0
*  -  These counters will show correct value when switch 
receives DHCP request packet with destination ip as broadcast
address. If request is unicast it will be HW switched
NEXUS-9000V-SW-1#

ما سبب تعقيد التكوين في Microsoft Windows Server 2012؟

• يحتوي Microsoft Windows Server 2012 على تجمع فائق (SuperScope) حيث توجد عناوين Loopback ومجمعات للشبكات الحقيقية.
• يقع اختيار التجمع لإصدار عنوان IP في SuperScope ، لأن الاستجابة جاءت من ترحيل DHCP من عنوان الاسترجاع المصدر المتضمن في SuperScope.
• باستخدام طلب سياسة ، فإنه يختار من Superscope نطاق الأعضاء الذي يكون VNI الخاص به موجودًا في معرف الدائرة الفرعية للخيار 82 من Suboption 1. ("0108000600" + 24 بت VNI + 24 بت لا أعرف قيمها ، لكن الشم يعرض القيم 0 في هذا المجال.)

ما مدى سهولة الإعداد في Microsoft Windows Server 2016/2019؟

• هل يمكننا الاستغناء عن النطاق الفائق؟
• هل يمكننا الاستغناء عن سياسة وترجمة VNI إلى شكل ست عشري؟
• هل يمكننا الاستغناء عن النطاق لعناوين مصدر الاسترجاع DHCP؟

 Note
All relay agent IP addresses (GIADDR) must be part of an active DHCP scope IP address range. Any GIADDR outside of the DHCP scope IP address ranges is considered a rogue relay and Windows DHCP Server will not acknowledge DHCP client requests from those relay agents.

A special scope can be created to "authorize" relay agents. Create a scope with the GIADDR (or multiple if the GIADDR's are sequential IP addresses), exclude the GIADDR address(es) from distribution, and then activate the scope. This will authorize the relay agents while preventing the GIADDR addresses from being assigned.

• إنشاء تجمع لعناوين ترحيل المصدر.
• إنشاء تجمع لشبكات العملاء

• إنشاء سياسة
• إنشاء SuperScope

مثال

DHCP ( 2 DHCP — VXLAN )

:

( — ):

Source DHCP Relay ( ):

تكوين خدمة DHCP على Microsoft Windows Server 2019

Loopback (source) DHCP Relay.

(Scope) IPv4.

. «Next >»

(Description) .

IP Loopback .

. .

. «Next >»

: DHCP (DNS, WINS, Gateway, Domain) . , . .

, , . «Finish»

. — Scope — «Activate».

/.

.

. «Next >»

(Description) .

IP Loopback .

. ( ) «Next >»

. «Next >»

: DHCP (DNS, WINS, Gateway, Domain) . .

.

DNS .

IP WINS .

Scope.

. «Finish»

استنتاج

قائمة المصادر

1. دليل تهيئة Nexus 9000 VXLAN 7.x
2. دليل تهيئة Nexus 9000 VXLAN 9.3
3. DFA (Cisco Dynamic Fabric Automation)
4. تكوين Microsoft Windows Server 2012 لتقديم خدمات DHCP في سيناريو eVPN (VXLAN ، Cisco One Fabric ، إلخ)
5. 3.4 DHCP Superscopes
6. مقدمة لسياسات DHCP
7. مشكلة Win2k8 R2 DHCP مع Option82
8. خيارات تحديد الشبكة الفرعية لـ DHCP