aci multisite ISN intersite network


aci multisite ISN intersite network

14.01 2020 | by massimiliano

aci multisite ISN intersite network   The different APIC domains are interconnected through a generic Layer 3 infrastructure, generically called […]



aci multisite ISN intersite network

 

The different APIC domains are interconnected through a generic Layer 3 infrastructure, generically called the Intersite Network (ISN)

 

 

The ISN requires plain IP routing support to allow the establishment of site-to-site VXLAN tunnels.

This requirement means that the ISN can be built in an arbitrary way, ranging from a simple single router device (two are always recommended for redundancy) to a more complex network infrastructure spanning the world

 

 

ISN also requires MTU support above the default 1500-byte value. VXLAN data-plane traffic adds 50 bytes of overhead (54 bytes if the IEEE 802.1q header of the original frame is preserved), so you must be sure that all the Layer 3 interfaces in the ISN infrastructure can support that increase in MTU size

 

 

Maximum MTU of the frames generated by the endpoints connected to the fabric: If the endpoints are configured to support jumbo frames (9000 bytes), then the ISN should be configured with at least a 9100-byte MTU value.

If the endpoints are instead configured with the default 1500-byte value, then the ISN MTU size can be reduced to 1600 bytes.

 

 

MTU of MP-BGP EVPN control-plane communication between spine nodes in different sites:

By default, the spine nodes generate 9000-byte packets for exchanging endpoint routing information.

If that default value is not modified, the ISN must support an MTU size of at least 9100 bytes.

The default value can be tuned by modifying the corresponding system settings in each APIC domain

 

 

The ISN also must support Open Shortest Path First (OSPF) to be able to establish peering with the spine nodes deployed in each site

 

 

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