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HSRP core switches


If i have two core switches running HSRP that have a 4 links trunk connected between two the two core switches.  My question on that trunk that connects the two core switches what kind of data goes thru from one core to another core.  I know HRSP sends Hello packets for in case if one core goes down the other becomes active however does data from one server connected to core 1 go thru the trunk link to communicate to another server connected on core 2 or is just for HSRP?




 Hi,It can be server traffic



It can be server traffic as well. Based on your defined config each switches may be acting as spanning tree root for different Vlans. In that scenario, not only HSRP and any dynamic routing protocol traffic but       client ->server and server ->server also uses that link.



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A host connected to core 1 but with its HSRP gateway on core 2, if sending to a host not on its subnet, would send it (at least) first packet to the HSRP gateway on core 2.  Whether this might use a trunk between core 1 and core 2 would depend on your L2 topology.


You asked about a server also on core 2, and the what I wrote applies, but it would also apply if that second server was also on core 1 (again, on a different subnet).


I wrote this applies to the first packet, but to be more precise it's the first packet that's first to the destination.  Depending on your configuration, and L3 topology, the HSRP gateway on core 2 could send a redirect to your sending server on core 1 to redirect its packets to a different gateway on core 1 (for example, using mHSRP).

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