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Local Host Routes Redistribute to routing table


Hello to all,

i am building a campus network with Cisco Catalyst 3850 switches in the access and 6800 at the core.

i want to design A routed Access - ospf between 3850 and 6800.

in some cases, i need to share same subnet between two 3850's - several hosts need to talk directly on the same subnet.

i dont want to open this connectivity at layer 2 and extending the vlan- i want to preserve the L3 between all switches.

a solution could be worked if in this specific vlan's i was able to install /32 hosts into the RIB - but i want the identification of the \32 host will be done automatically - without using static routes to null 0. (the Case is IPv4)

i dont mind configuring specific vlans which in those vlans all connected hosts will redistribute into the routing tables.

any ideas ?

 (Cannot to LISP EID notify as the 3850 dont support it )




1 Reply 1

Bilal Nawaz

Hello Avi, any particular reason why you cannot just stack your 3850's? Apart from this you could have L2 between your Access switches, then have L3 from both access switches to the core, split your subnet (in the way you advertise out)

So as an example, calve up a /24 in to x2 /25's (use one access switch for each) - advertise them out as /25's but keep the actual L2 subnet /24. That way you can have optimised routing and also your subnet/vlan the same. However comes at a cost, your IP addressing will need to be taken care of for this LAN to ensure you have optimal packet/frame flows. So hosts should be connected to their relevant /25 switch.


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