Ask the Expert: NGWC (3850/5760): Architecture and Deployment

[ciscomoderator]

Welcome to the Cisco Support Community Ask the Expert conversation. This is an opportunity to learn and ask questions about NGWC (3850/5760): Architecture and Deployment.

Ask questions from Monday, April 13th, 2015 to Friday, April 24th, 2015

This Ask the Expert Session will cover questions spanning NGWC products (3850/5760) on Implementation and Deployment from the Wired and Wireless perspective. This will be more specific to Customer’s and Partners questions covering 3850/5760 configuration, Implementation and deployment.

Dhiresh Yadav is a customer support engineer in High-Touch Technical Services (HTTS)  handling supporting Wireless and Network Management based Cisco products and is based in Bangalore. His areas of expertise include Cisco Wireless CUWN and NGWC Product line. He has over 7 years of industry experience working with large enterprise and service provider networks. He also holds CCNP (RS) and CCIE (DC-Written) and CCIE Wireless certification.

Naveen Venkateshaiah is working as a Customer support engineer in High-Touch Technical Services (HTTS) handling  and supporting Lan-switching and Data center Products. His areas of expertise include Catalyst 3k,4k , 6500 , Nexus 7k Platform  He has over 7 years of industry experience working with large Enterprise and Service Provider networks. He also holds CCNA, CCNP (RS) and  CCDP-ARCH,CCIE-R&S Written, AWLANFE, LCSAWLAN Certification.

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[Diburaj K P]

How this 3850 architecture supports all this functionality for example wireless ? Its doesnt have Physical module like wism , correct ?

[Dhiresh Yadav]

Hi ,

Thanks for raising this question. This is where Converged access difference comes in to picture as compared to normal IOS. In WiSM module , although we insert the module inside the 6500 switch but the IOS is still different which means that module still works on AireOS while rest of the switch on IOS.

On converged access/NGWC , the wireless is integrated inside the IOS-XE package. So the command line used to access switch or wireless is same. The ability to host different software packages on the linux kernal in CA solution makes this possible. So if you do "sh flash" on the CA box , you will see all the Software packages inside the XE platform. For example if IOS-XE version is 3.6.2 , then you will see wireless controller module package as 10.2.102.0 while it would be different for IOSd module which would carry out wired functions.

Let me know if you have any further doubt.

Regards

Dhiresh

[Naveen Venkateshaiah]

Hi,

Let me add on this in some more detail.

 Cisco 3850 switches that provide full convergence between wired and wireless on a single platform. With IOS-XE software, wireless service is supported through the Control and Provisioning of Wireless Access Points (CAPWAP) protocol. Cisco's new Unified Access Data Plane  (UADP) ASIC powers the switch and enables uniform wired-wireless policy enforcement, application visibility, flexibility.

 We have Wireless control module (WCM) is a hosted application over Linux kernel that enables coexistence and giving single operational user experience with single Cisco  IOS Software to manage wired and wireless infrastructure in a single system.
A mobility agent is an access switch such as Catalyst 3850 with a wireless module running on it , it has CAPWAP tunnels of directly connected access points and maintaining client mobility state machine

 For an example you a sample network : You have endpoints  connected through wired to the  switch, through  wireless to the AP connected to the access switch;
 You also have a WLC in the data center. There is a host  that manage different aspects of the network – like policy, security, HW informations , wired network management, wireless network management. The present Wireless is centralized overlay model , where all  traffic to and from wireless has to pass through the centralized WLC. The network infrastructure has no visibility into wireless traffic , except just knowing its CAPWAP traffic , so we cannot apply any features to it. Thus how Catalyst 3850 comes in ,giving you true  wired-wireless convergence and scalability.  

The 3850 can be just be a wired switch, or a fully integrated and functional wireless controller. In the middle ground, it can terminate AP CAPWAP tunnels and work with an existing WLC ,5508 or WiSM2 in the network. All the wireless traffic is now terminated on the 3850 , giving the wireless network a form of distributed data plane. With the local termination, you can distribute wireless capacity in your access switches and the network infrastructure  gains visibility into wireless traffic enabling application of consistent policies and features with wired traffic.

 Let me know if I am able to answer your question correctly.

Regards,
Naveen Venkateshaiah.

[aravinda099]

Does NGWC support Multicasting , mDNS , DNS-SD on Flexconnect mode AP s ? 

[Dhiresh Yadav]

Hi Arvind,

Thanks for asking this question.

Yes , NGWC supports multicast , the same way it is supported in CUWN today i.e Multicast unicast and multicast multicast. Multicast to Multicast is same but Multicast to unicast is handled in better way on Converged access, Instead of doing unicast of multicast packet to each AP like in CUWN , converged access controllers , forwards to APs having clients for the multicast group instead of all the APs.

For the flex connect mode AP , this mDNS and DNS-SD depends upon the central switch vs locak switching and here is the behavior:

For centrally switched WLANs, the behavior for Bonjour is the same as if the AP was in local
mode.
> Bonjour queries from the client are sent to the controller and Bonjour responses from the
controller are sent back to the AP in the unicast CAPWAP tunnel.
> FlexConnect APs do not require the Multicast‐Unicast mode to support Bonjour.

Local switched WLan
> For locally switched WLANs, Bonjour continues to work in a single subnet only.This is any way by default supported since day 1 in mDNS.

This link will provide a bit more information on this:

https://supportforums.cisco.com/document/12068926/common-apple-bonjour-and-cisco-wireless-related-issues

Let me know if I answered your query.

Regards

Dhiresh

[Rasika Nayanajith]

Hi Dhiresh,

Local switched WLan
> For locally switched WLANs, Bonjour continues to work in a single subnet only.This is any way by default supported since day 1 in mDNS.

In 8.0 config guide it stated like this under Restriction for mDNS section,  Is that wrong info ?

http://www.cisco.com/c/en/us/td/docs/wireless/controller/8-0/configuration-guide/b_cg80/b_cg80_chapter_01011.html#reference_18F93527402844C8BA8A5FFAC607AA0D

• mDNS is not supported on access points in FlexConnect mode in a locally switched WLAN and mesh access points.

HTH

Rasika

[Dhiresh Yadav]

Hi Rasik,

Thanks for the question.

Link local multicast will always work in the same vlan irrespective of Wired or wireless.

It is clearly written here

http://www.cisco.com/c/en/us/td/docs/wireless/technology/bonjour/Bonjour74/Bonjour_Deployment.html

Looks like there is misunderstanding of words. Whenever they talk about  mDNS configuration on the wireless device , they normally mean learning the services and for that client traffic should be sent to the controller , which is not possible in the lcoal switched wlan but possible in central switch wlan. SO they have mentioned it will not work on flex connect local switched wlan. To work in the same vlan , you even dont need any mDNS configuration/discussion from the wireless device perspective.

Hope this clarifies.

Regards

Dhiresh

[Dhiresh Yadav]

Hi Rasika,

Thanks for the question.

Link local multicast inside the vlan would be supported irrespective of the wired or wireless.

For wireless , it is supported inside the local vlan of locally switched wlan:

http://www.cisco.com/c/en/us/td/docs/wireless/technology/bonjour/Bonjour74/Bonjour_Deployment.html

About the configuration guide , Normally when they talk about any mDNS configuration or discussion with respect to any Wireless device they mean learning the mDNS services which is not possible if the client traffic is locally switched and possible only in the central switch scenario , hence the statement .With in the subnet functioning of the Bonjour services doesnt need any mDNS configuration/discussion for the contrller/AP.

If you still think that the statement is not very clear and is confusing , Please go ahead and raise a TAC case for a documentation bug but chances that they would accept it are very less given the context.

Hope this clarifies.

Regards

Dhiresh

[Dhiresh Yadav]

Hi Rasika,

Sorry for the two replies . I thought first one never got posted.

Regards

Dhiresh