The corresponding solutions for each of the scenarios outlined in section 2 are different and that¹s why they are listed as such.
Scenario-1 doesn¹t require any DCI solution and doesn¹t require any interop to IP-VPN Scenario-2 requires a DCI solution w/o maintaing an IP-VRF at the GW Scenario-3 requires a DCI solution that needs an IP-VRF at the GW Scenario-4 requires inter-op between EVPN and IP-VPN Cheers, Ali On 2/18/15, 6:53 PM, "Russ White" <[email protected]> wrote: >Before I get into a lot of edits and thoughts -- In section 2: > >== >In the above scenario, the term "route aggregation" refers to the case >where >a node situated at the WAN edge of the data center network behaves as a >default gateway for all the destinations that are outside the data center. >The absence of route aggregation refers to the scenario where NVEs within >a >data center maintain individual (host) routes that are outside of the data >center. >== > >Reading through the rest of the draft, there seems to be a lot of >interchange between "WAN gateway," "route aggregation," and "default >gateway." Let me try describing two switching paths, and then try to sort >if >they actually cover all the different scenarios given in the draft. > >Assume you have: > >TS1--NVE1--R1--R2--NVE2--TS2 > >TS1 wants to send a packet to TS2; however, TS2 is on a different subnet. >TS1 examines its local tables, and determines that TS2 is on a different >subnet, so it transmits the packet to the default gateway (it actually >doesn't matter if TS1 itself sends this packet, or if TS1 is a switch, and >some device behind TS1 sends this packet -- the result is the same). In >this >case, let's assume NVE1 is the default gateway, so it receives and must >process the packet. There are two options at this point. > >NVE2 could have a routing entry directly to TS2 which includes layer 2 >information through an EVPN advertisement in BGP (or other means outside >the >scope of the document). In this case, NVE2 uses the layer 2 information >contained in the BGP advertisement to build a MAC header rewrite string, >stuffs the packet into the correct outer header (MPLS or VXLAN or whatever >else), and ships it towards NVE2. NVE2 pulls the tunnel headers and >fowards >based on the layer 2 information. > >NVE2 could have a routing entry directly to TS2 which does not include >layer >2 information. In this case, NVE2 simply forwards the packet based on any >local layer 3 information it might have. Let's say this layer 3 >information >is either a default or more specific route advertised by R2. In either >case, >NVE1 wraps the packet in the correct tunnel information to reach R2 and >ships it. R2 removes the tunnel information and forwards it to NVE2 based >on >local forwarding information (which could be a layer 2 advertisement or a >layer 3 advertisement -- from NVE1's perspective this isn't important). > >These two seem to cover all five of the possibilities covered in section >2. >Where TS2 is located -- within or outside the local data center -- doesn't >really make any difference (unless you assume there will never be a >default >route advertised between IP subnets within a data center, or there will >never be IP only connectivity between two different subnets within the >same >data center, both of which seem like a bad assumptions to me). Is there a >specific reason why the location of the "wan default gateway" makes any >real >difference in the different scenarios? Or why the default route is a >special >case (other than requiring the device advertising the default route to be >able to interconnect an EVI and an IP-VPN)? > >Russ > >_______________________________________________ >BESS mailing list >[email protected] >https://www.ietf.org/mailman/listinfo/bess _______________________________________________ BESS mailing list [email protected] https://www.ietf.org/mailman/listinfo/bess
