Re: Creating redundant routed links on 3750 stack switches

gdrandles · ‎02-10-2010

I have 14 buildings in my Campus Area Network. The 13 buildings have 2 fiber pair running to the core (14th building). I am using stacked 3750 switches in each building and want to know how I can create routing redundancy between each spoke and the hub. I know that you can use etherchannel for trunk links. Each building has 5 floors and I am running etherchannel from floors 2-4 down to the first floor and then routing over to the core. Before the upgrade to 3750 switches I was running hsrp. I guess my second quesiton is there a performance increase in stacking and creating redundant layer 3 routed links to the core or split the stacks and run hsrp?

Thanks in advance,

George

Ganesh Hariharan · ‎02-10-2010

I
have 14 buildings in my Campus Area Network.  The 13 buildings have 2
fiber pair running to the core (14th building).  I am using stacked
3750 switches in each building and want to know how I can create
routing redundancy between each spoke and the hub.  I know that you can
use etherchannel for trunk links.  Each building has 5 floors and I am
running etherchannel from floors 2-4 down to the first floor and then
routing over to the core.  Before the upgrade to 3750 switches I was
running hsrp.  I guess my second quesiton is there a performance
increase in stacking and creating redundant layer 3 routed links to the
core or split the stacks and run hsrp?
Thanks in advance,
George

Hi George,

How is the current routing between hub and spoke ? If a default route towards a Hub and you want redundacny for secondary link also then configure a floating static route in spoke location for the second link interface with ip sla configuration for automatic failover in case any fault in primary link.

Check out the below link for ip sla track command configuration

http://www.ciscosystems.am/en/US/docs/switches/lan/catalyst3750/software/release/12.2_40_se/configuration/guide/swhsrp.html

Hope to help

Ganesh.H

rajatsetia · ‎02-10-2010

By enabling routing between spoke and hub you are restricting the layer 2 boundary to the individual building which will result in smaller broadcast domain (which then leads to multiple advantages) and more stability as STP boundary is now doesn't extend to the core.

Any goof up at any floor of any building wonnt disrupt you whole network as STP will not cross the layer 3 boundary between spoke and hub.

Redundancy can be achieved by enabling routing protocol like OSPF with HUB as ABR and Spokes as stub and send only default route to them

or EIGRP (depending on your preference)

HTH

gdrandles · ‎03-15-2010

Thanks for the responses. I ended up using port-channel to combine the two Fiber Links between each building and the core. I used the following config if as an FYI for anyone else:

Created the port-channels at the core first- (Only Showing 3 building as an example)

interface port-channel 1

no switchport

ip address 192.168.1.1 255.255.255.252

interface port-channel 2

no switchport

ip address 192.168.1.5 255.255.255.252

interface port-channel 3

no switchport

ip address 192.168.1.9 255.255.255.252

Added the interfaces to each port-channel at the core-

interface ra gig 1/0/1, gig 2/0/1

no ip address

no switchport

channel-group 1 mode active

interface ra gig 1/0/2, gig 2/0/2

no ip address

no switchport

channel-gropu 2 mode active

interface ra gig 1/0/3, gig 2/0/3

no ip address

no switchport

channel-group 3 mode active

Use the show ether sum to display the status of each port-channel and associated physical interfaces. I now have 2Gb uplinks and still have redundancy if 1 physical link fails.

HTH Anyone else,

Damien