HSRP query

mulhollandm · ‎07-24-2008

folks

i'm running hsrp for the first time on a pair of 3800s and i have a query

is this a true cluster, .i.e. are configuration changes, routing updates etc propagated from one machine to another?

thanks to anyone taking the time to reply

lee.reade · ‎07-24-2008

Hi,

HSRP is a first hop redundancy protocol, is provides redundancy to your clients (workstations/servers) default gateway.

Therefore there is no config as such to replicate between the devices, each switch is configured as a standalone unit, then the hsrp grouping binds them together so that they share an active ip address, when the primary routers goes down (interface failure/hardware failure etc) then the secondary router, noticing missed keepalives from the primary, takes over the ip address, and begins responding to arp requests from the clients/servers for the default ip address mac address.

So the answer to your question is no, this is not a true cluster.

Check out;

http://www.cisco.com/en/US/docs/ios/ipapp/configuration/guide/ipapp_hsrp_ps6350_TSD_Products_Configuration_Guide_Chapter.html

HTH

LR

Giuseppe Larosa · ‎07-24-2008

Hello Michael,

the answer is NO . HSRP just provides a virtual default gateway to end users PCs and servers.

It doesn't provide a failover or stateful communication between the two devices (like a PIX pair)

The default gateway is emulated at L2 and L3 by the two routers.

see the following links:

http://www.cisco.com/en/US/prod/collateral/routers/ps5855/white_paper_c11_472858.html

http://www.cisco.com/en/US/prod/collateral/routers/ps5853/prod_white_paper0900aecd805bbf96_ps5855_Products_White_Paper.html

Hope to help

Giuseppe

mulhollandm · ‎07-24-2008

guiseppe/lee

many thanks for your replies, they are greatly appreciated

if i want stateful switchover do i have to run the classic firewall on the 3800 (it acts as a border router & i have 2 firewalls behind it)?

thanks again

Giuseppe Larosa · ‎07-24-2008

Hello,

thanks for your good marks.

If you already have two firewalls you don't need that.

With HSRP you can track interfaces so you can make the two 3800 to adapt to network changes.

This should be enough to complete your solution.

Hope to help

Giuseppe

lee.reade · ‎07-24-2008

Hi,

What kind of statefull switchover are you looking for?

Are you talking about NAT etc?

Where are you looking to run hsrp? What kind of firewalls do you have? As you could just run the hsrp/vrrp across the firewall pair instead.

HTH

LR