StackwisePlus and EIGRP

[mohankumarm]

Hello

We are currently designing  Layer 3 to the edge EIGRP solution  for our customers. The network is a hybrid of collapsed  core (Core to access) as well as a three layer design (Core/Distro/Access) for connectivity to the Data Centre, Internet, Wireless Blocks etc.

The  core of the network contains two 6509-E switches interconnected on a  Layer 3 Port channel (no VSS). Access Layer switches (3750-X series running Stackwiseplus protocol)  connect to the core switches over p2p routed links and Distribution layer switches (3750X stackwiseplus) provide connectivity to the  Data centre, Internet, wireless blocks etc.

The access and distribution switch stacks(Cisco 3750-X) are set up with two or three member switches with uplinks multihomed to the primary and secondary core switch with each uplink included in EIGRP. In each of the stacks, one of the switches controls the operation of the stack, which will be  the stack master.

As the Cisco Stackwise architecture is not SSO-capable but NSF aware, all Layer 3 fuctions must be re-established during a master switch outage. To minimize control plane impact and improve Layer3 convergence, uplinks should be diverse and originate from the member switches instead of the Master switches in the respective stack. This is as per Cisco recommended design solution.

My question is as follows:

The above solution can be setup if there are more than two switches in the stack. i.e. uplinks are configured on the backup member switch modules.

1.But what about stack with two switches..Which switch should be set up as the Master for a two member stack with uplinks to the core primary and secondary from each switch(Master and Backup)

2. For Layer 3 routing, does the routing takes precedene over switch failures? Say for eg. In a two member stack, the master switch with uplink to primary fails, does EIGRP provide a fast convergence to route traffic via backup secondary and does not wait for the control plane on the switch stack to converge? All the access to core links will be set up for ECMP.

Thanks and Regards,

Mohan

[Joseph W. Doherty]

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Posting

I thought the later IOS images for 3750-E/X did support NSF capability.

Reference:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750x_3560x/software/release/12.2_55_se/configuration/guide/swiprout.html#wp1381590

[mohankumarm]

Hi Josesph,

Thanks for your message and as per the reference above the NSF capability for EIGRP seems to be only on the "IP Services" IOS image on the switches and unfortunately all switches have been ordered with IP Base versions only and the only IP Base version which seems to support NSF on the current design is on the Cisco 6504-3 VSS running IOS 12233SXI.

Thanks and Regards,

Mohan

[Joseph W. Doherty]

Disclaimer

The     Author of this posting offers the information contained within this     posting without consideration and with the reader's understanding  that    there's no implied or expressed suitability or fitness for any   purpose.   Information provided is for informational purposes only and   should not   be construed as rendering professional advice of any kind.   Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In     no event shall Author be liable for any damages whatsoever   (including,   without limitation, damages for loss of use, data or   profit) arising  out  of the use or inability to use the posting's   information even if  Author  has been advised of the possibility of  such  damage.

Posting

Yes, that's likely true, i.e. IP Services feature set is required for NSF EIGRP on 3750-X.  I believe IP Services is also required for "full" EIGRP support too.