Multi PoP deployments

Following aspects should be taken care in cnWave Multi PoP deployments

Layer 2 domain

All cnWave PoP nodes must be connected to the same Layer 2 broadcast domain. PoP nodes learn about other PoP nodes using IPv6 multicast packets, which do not cross broadcast domain.

This allows cnWave PoP nodes to forward traffic to other cnWave PoP nodes via a wired connection when the routing path of the other PoP node is closer to the traffic’s destination. This concept is known as tromboning, because the traffic enters a PoP node and then leaves toward another PoP node.

Open/R on the PoP interface port

PoP interface port should be configured to run Open/R protocol. This can be done by marking the port as Multi PoP/ Relay port.


MTU of upstream switch ports

PoP ports use an 2000 MTU size. So, all the switch ports should be atleast 2000. Even if the user traffic is limited to 1500 sized packets, switch ports should allow the higher MTU size. Following packets exchanged between PoPs can be of higher size - Open/R packets, L2GRE packets (in Layer 2 mode), Software download packets.

Prefix Allocation

Its is recommended to use Deterministic Prefix Allocation



Hi Kiran,

Do all wired ports in the physical path between PoP nodes need to support larger MTU size?

@Enzo_Tirone Thats correct.

Thanks for the response. I noticed that in the user guide there is a disclaimer which notes that “Multi-PoP deployment is not recommended if onboard E2E is enabled”.

Are you able to provide more info on why it is not recommended and what are the limitations/risks if Multi-Pop is deployed with onboard E2E?

Disadvantages of onboard controller

  • Topology is limited to 21 nodes. Typically a single POP would suffice for a small network
  • In Multi POP deployments, if the POP hosting E2E goes down, the network will no longer be manageable.
  • Upcoming Network Analyzer and Network Optimizer (NANO) features require external E2E.
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Aside form what you have mentioned, do you see any issues/challenges with having Multi-Pop in a 21 node network?

Thank You

Otherwise, it works.

Does the MTU on the E2E Controller need to be 2000 bytes or can it be 1500 bytes MTU on the E2E Server, is 2000 bytes MTU just required for DN’s to Communicate or also for E2E to communicate to the DN’s

Setting the MTU size to 2000 is only necessary for POPs to communicate with each other via their wireline interface (core switch interfaces / bridge that all the POPs use). It is not necessary to set an MTU of 2000 on the E2E controller interface.

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With the requirement for DN’s / POPs and E2E Controller to all be in the same Layer 2 Domain , is there any potential issues with using MPLS/VPLS / Tunnels between POPs and the E2E controller instead of a flat switched network ?

If I understand it right, at the end all of them will be in same broadcast domain. So Tunnels between POPs and controller is fine.