SWITCHING REDUNDANCY

[Mohammed Shoukat Ali]

Dear Experts,

I want to add backup switch in my network, current setup i have one Router one switch 3750 with WAN Link and some of Access switches.

Now we have another WAN link as a backup so I have to add another Router and switch 3750 in network. My question is that shall I connect new switch as stacking or with separate Link like Port-channeling to my existing switch which one is the easiest way to  configure. Existing switch I have Static routes. If I configure new Router what could be the Lan Interface IP shall I configure same existing Range or different. Please advice.

Attached file network diagram for more understanding.

Many thanks,

[jhager001]

I think you should stack the 3750's and create port-channels from the access switches up. you could even create port-channels to the router's if you had enough available ports, maybe an HWIC card, and assign each device a single port on each switch. this would provide redundancy through the switch. Then you could create HSRP link in the router.

[Mohammed Shoukat Ali]

Hi jhager,

Thanks for your support.

Currently we don't have enough ports on service provider router, If I put stacking the new switch there is no redundancy the idea is if one wan link goes down we can utilise second wan link. Router 1 Lan ip is  10.1.1.9 shall I configure same range or different subnet like 10.1.2.9 because my first I have some static routes configured in Sw1 192.168.2.0 255.255.255.0 10.1.1.9 . If I create new router2 Lan ip 10.1.2.9 so in my sw2 static routes 192.168.2.0 255.255.255.0 10.1.2.9 like this it will work please correct me if I'm wrong.  Please advice.

Many thanks,

[Ganesh Hariharan]

Dear Experts,


I want to add backup switch in my network, current setup i have one Router one switch 3750 with WAN Link and some of Access switches.

Now we have another WAN link as a backup so I have to add another Router and switch 3750 in network. My question is that shall I connect new switch as stacking or with separate Link like Port-channeling to my existing switch which one is the easiest way to  configure. Existing switch I have Static routes. If I configure new Router what could be the Lan Interface IP shall I configure same existing Range or different. Please advice.


Attached file network diagram for more understanding.

Hi Mohammed,

If the secondary wan link also from same provider , Then you have two option either two have stack 3750 switches and connect all access layer double uplink to both the switches.

or two have standalone switch with port channel configured with double uplink from all access layer switches.

Considering single WAN provider then and is ISP is running any type of dynamic routing protocol with you in lan side or just static routing.

If dynamic then you can run the same either EIGRP or OSPF for automatic failover, If not static then use IP SLA for automatic failover to secondary link by pointing best metric route towards primary and higher AD route to secondary.

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/release/12-2_55_se/configuration/guide/scg3750/swipsla.html

Hope it helps..

-GI

Rate if it Helps..

[Mohammed Shoukat Ali]

Hi Ganesh,

Thanks for your response.

Second WAN link is also from the same provider. if I go with two standalone switches with port-channeling, What could be the LAN int IP for my second WAN router ? will it have the same range as now or shall I configure with a different range. Currently I have configured all static routes in my first switch pointing to First WAN link Int IP that is my gateway. If I configured second Switch, what  static routes shall I point to Second WAN Link Int IP. Please Advice.

Many thanks,

[Ganesh Hariharan]

Hi Ganesh,

Thanks for your response.

Second WAN link is also from the same provider. if I go with two standalone switches with port-channeling, What could be the LAN int IP for my second WAN router ? will it have the same range as now or shall I configure with a different range. Currently I have configured all static routes in my first switch pointing to First WAN link Int IP that is my gateway. If I configured second Switch, what  static routes shall I point to Second WAN Link Int IP. Please Advice.

Many thanks,

Hi Mohammed,

Is these WAN routers are managed by providers or by urself, If it is managed by yourself then best and simple design is to have common subnet between the 4 devices ( 2* 3750 & 2 * WAN routers), so that you can run HSRP in you WAN router towards LAN interface and point the default static route towards virtual ip address from 3750 switches.

and on WAN router you can perform IP SLA to shutdown the external link and automatic failover to secondary WAN router as part of High availability.

Hope it Helps..

-GI

Rate if it Helps

[Mohammed Shoukat Ali]

Hi Ganesh,

WAN Routers are managing by service provider and they have to configure HSRP from their side. I will configure stacking with same subnet R1 & R2. 

Thanks for your help.

[Ganesh Hariharan]

Hi Ganesh,

WAN Routers are managing by service provider and they have to configure HSRP from their side. I will configure stacking with same subnet R1 & R2. 


Thanks for your help.

Hi Mohammed,

That should be fine, and traffic flow would easy for you to point towards HSRP VIP from your switches.

I hope you got all query clarified..

-GI