I thought I’d share some example configuration for a scenario where you may have Cisco WLCs connecting to either one or two Advanced Services Routers (ASR) for the Layer 3 core as opposed to a Layer 3 switch.  If you’ve ever configured an ASR (in this case an ASR920) you’ll know that the configuration of VLAN interfaces and 802.1Q trunking is much different to an ISR or Catalyst switch.

In this scenario there were two 5520 WLCs in a HA pair (both in the same data centre) each with single 10Gbps uplinks to an ASR920 (primary & secondary).  ‘Why no LAG?’ you might ask.  The ASR920 only supports LACP with active and passive modes, it doesn’t support ‘channel-group X mode on‘ which is required for LAG.

Here is example configuration for the WLC management interface (trunked for centrally-switch wireless LANs) on one ASR 920 (the config is the same on both ASRs) with some sample VLAN numbers:

interface GigabitEthernet0/0/22
 description WLC-P001|Port 1|WLC 1
 no ip address
 load-interval 30
 negotiation auto
 cdp enable
 service instance 1 ethernet
 description Native - VLAN 1
 encapsulation untagged
 l2protocol peer cdp
 bridge-domain 1
 !
 service instance 200 ethernet
 description mgmt1
 encapsulation dot1q 200
 rewrite ingress tag pop 1 symmetric
 bridge-domain 200
 !
 service instance 201 ethernet
 description wifi1
 encapsulation dot1q 201
 rewrite ingress tag pop 1 symmetric
 bridge-domain 201
 !
 service instance 202 ethernet
 description ap1
 encapsulation dot1q 202
 rewrite ingress tag pop 1 symmetric
 bridge-domain 202
 !
 service instance 220 ethernet
 description data1
 encapsulation dot1q 220
 rewrite ingress tag pop 1 symmetric
 bridge-domain 220
 !
 service instance 221 ethernet
 description gue_wifi1
 encapsulation dot1q 221
 rewrite ingress tag pop 1 symmetric
 bridge-domain 221
 !
 service instance 222 ethernet
 description gue_wifi2
 encapsulation dot1q 222
 rewrite ingress tag pop 1 symmetric
 bridge-domain 222
!
 service instance 660 ethernet
 description data1
 encapsulation dot1q 660
 rewrite ingress tag pop 1 symmetric
 bridge-domain 660
 !
 service instance 661 ethernet
 description voice1
 encapsulation dot1q 661
 rewrite ingress tag pop 1 symmetric
 bridge-domain 661
 !
end

Note: you need to include bridge domain 1 as untagged for CDP and other Layer 2 protocols to work across the link.

Here is an example of an access port uplink, such as the WLC CIMC interface:interface

GigabitEthernet0/0/23
 description WLC-P001|CIMC|WLC 1
 no ip address
 load-interval 30
 negotiation auto
 cdp enable
 service instance 200 ethernet
 description mgmt1
 encapsulation default
 bridge-domain 200
 !
end

I hope that helps someone with a similar deployment in future!

Shout out in the comments if you need a hand with ASR bridge domain/Layer 3 interface configuration.

Posted by Wi-Fi Coops

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s