VRF-aware DHCP relay

DHCP/vrf-relay/README.md

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+# VRF-aware DHCP relaying
+
+This directory contains *netlab* topology file for a simple VRF-aware DHCP relaying scenario.
+
+![DHCP relaying topology](dhcp-relay.png)
+
+After starting the lab, the *user* device should get DHCP-assigned IP address on its lab-facing interface.
+
+## Changing Device Types
+
+This topology can be used with Cisco IOSv or Arista EOSv. To test it with other devices, add custom configuration template to `dhcp-relay` directory.
+
+The easiest way to change the device types is to edit the topology file. You could also use the **netlab up** [CLI arguments](https://netsim-tools.readthedocs.io/en/latest/netlab/up.html#usage) -- to change the DHCP relay device type, use `-s nodes.relay.device=xxx` CLI argument.

DHCP/vrf-relay/dhcp-client/ios.j2

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+{% for intf in interfaces if intf.dhcp.client is defined and intf.dhcp.client %}
+interface {{ intf.ifname }}
+ no ip address
+ ip address dhcp
+{% endfor %}

DHCP/vrf-relay/dhcp-relay/eos.j2

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+{% for intf in interfaces if intf.dhcp.server is defined and intf.vrf is defined %}
+{%   if loop.first %}
+ip dhcp relay information option
+{%   endif %}
+{% endfor %}
+!
+{% for intf in interfaces if intf.dhcp.server is defined %}
+{%   set helper = hostvars[intf.dhcp.server].loopback.ipv4|ipaddr('address') %}
+interface {{ intf.ifname }}
+ ip helper-address {{ helper }}{% if intf.vrf is defined %} vrf default{% endif %}
+{% endfor %}

DHCP/vrf-relay/dhcp-relay/ios.j2

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+{% for intf in interfaces if intf.dhcp.server is defined and intf.vrf is defined %}
+{%   if loop.first %}
+ip dhcp relay information option vpn
+{%   endif %}
+{% endfor %}
+!
+{% for intf in interfaces if intf.dhcp.server is defined %}
+{%   set helper = hostvars[intf.dhcp.server].loopback.ipv4|ipaddr('address') %}
+interface {{ intf.ifname }}
+{%   if intf.vrf is defined %}
+ ip helper-address global {{ helper }}
+{%   else %}
+ ip helper-address {{ helper }}
+{%   endif %}
+{% endfor %}

DHCP/vrf-relay/dhcp-server.j2

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+logging buffered
+no service timestamp debug
+!
+do debug ip dhcp server packet
+do debug ip dhcp server event
+!
+{% for h,v in hostvars.items() %}
+{%   for intf in v.interfaces if intf.dhcp.server is defined and intf.ipv4 is defined %}
+ip dhcp excluded-address {% if intf.vrf is defined %}vrf {{ intf.vrf }} {% endif %}{{ intf.ipv4|ipaddr('address') }}
+{%   endfor %}
+{% endfor %}
+!
+{% for h,v in hostvars.items() %}
+{%   for intf in v.interfaces if intf.dhcp.server is defined and intf.ipv4 is defined %}
+!
+ip dhcp pool p_{{ intf.ipv4|ipaddr('network') }}
+{%     if intf.vrf is defined %}
+ vrf {{ intf.vrf }}
+{%     endif %}
+ network {{ intf.ipv4|ipaddr('network') }} {{ intf.ipv4|ipaddr('netmask') }} 
+ default-router {{ intf.ipv4|ipaddr('address') }}
+{%   endfor %}
+{% endfor %}

DHCP/vrf-relay/graph.dot

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+graph {
+  bgcolor="transparent"
+  node [shape=box, style="rounded,filled" fontname=Verdana]
+  edge [fontname=Verdana labelfontsize=10 labeldistance=1.5]
+  "srv" [
+    label=<srv [iosv]<br /><sub>10.0.0.1/32</sub>>
+    fillcolor="#ff9f01"
+  ]
+  "relay" [
+    label=<relay [iosv]<br /><sub>10.0.0.2/32</sub>>
+    fillcolor="#ff9f01"
+  ]
+  "user" [
+    label=<user [iosv]<br /><sub>10.0.0.3/32</sub>>
+    fillcolor="#ff9f01"
+  ]
+ "relay" -- "srv" [ width=5 ]
+  "relay_2" [style=filled fillcolor="#ff8080" fontsize=11 label=<172.16.0.0/24<br />VRF client>]
+ "user" -- "relay_2" [ color="#800000"  width=5 ]
+ "relay" -- "relay_2" [ color="#800000"  width=5 ]
+}

DHCP/vrf-relay/topology.yml

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+message: |
+  This topology sets up a simple network using VRF-aware DHCP relay
+  functionality. It includes a DHCP server (running on Cisco
+  IOSv), DHCP client (also on Cisco IOSv) and an intermediate
+  node.
+
+defaults.attributes:
+  link.dhcp:
+    client: bool
+    server: str
+
+defaults.device: iosv
+
+groups:
+  dhcp_server:
+    members: [ srv ]
+    module: [ ospf ]
+    config: [ dhcp-server ]
+    device: csr
+  dhcp_client:
+    members: [ user ]
+    config: [ dhcp-client ]
+    device: iosv
+  switch:
+    members: [ relay ]
+    module: [ ospf,vrf ]
+    config: [ dhcp-relay ]
+
+vrfs:
+  client:
+
+nodes: [ srv, relay, user ]
+
+links:
+- relay-srv
+- user:
+    dhcp.client: True
+  relay:
+    dhcp.server: srv
+  type: lan
+  vrf: client