The original 3750G-12S, designed for distribution, had a larger TCAM and additional SDM templates. I can only guess that Cisco found having a "special" variant wasn't worth the trouble or they decided they didn't want to compete against other products in their line (existing or planned) that would be more suitable in such a role for larger networks. Either might explain why the 3860XS is as it is.
I haven't any direct experience with the3650/3850 series, but assuming its architecture is somewhat similar to earlier 3560/3750 series, I would expect the number of routes supported to be a global resource, i.e. I would expect it to be shared across VRFs.
Although Mark's references notes IPv4 routes as 24K, table 1 in http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-3850-series-switches/deployment_guide_c07-727067.html, lists
|
Resource
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Advanced Template
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VLAN Template
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Resource Explained
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|
Indirect routes
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8192
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8192
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Maximum supported indirect routes
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This document also notes:
Table 1 details the resource allocation for VLAN and advanced SDM templates. These resource allocations are based on L2 and IPv4 features. Because IPv6 features consume twice the ternary content addressable memory (TCAM) table size of IPv4 table entries, the switch supports half the number of TCAM table entries for IPv6.
In my company, we didn't move from 3750s to 3850s for similar concerns especially as we were looking to roll out IPv6.
