SoftLayer Subnets on same VLAN does not communicate with each other after VLAN Spanning turned off

0
votes

We were testing with configuration as VLAN SPAN off. However we observed that subnets on the same VLAN could not talk to each other as well after VLAN SPAN turned off. This is totoally unexpected and does not make sense according to http://knowledgelayer.softlayer.com/faq/what-vlan-spanning

As VLAN spanning off is supposed to only prevent traffice between different private VLANs instead of blocking cross-subnets in the same VLAN as well. Could someone please help clarify the restriction here and also how we could do cross-subnets comm without turning VLAN Spanning back on? Thanks much.

1
ibm-cloud-infrastructure

1 Answers

0
votes

I did some tests in Amsterdam 01 datacenter, and it is working fine. Which datacenter and vlan are you using? Also, you can submit a ticket for further assistance

Updated

My sincere apologies, I did the tests after few minutes but sometimes the "Vlan Span" takes a little more time to take effect (5 minutes more or less).

According to Development, this is expected behavior. without vlan spanning enabled, communication between subnets on the same backend VLAN is not routed by SoftLayer's network. ,

Subnets on the same VLAN can communicate with one another, but you'll have to teach each node about its fellow subnets such that our gateway is not carrying the traffic

For instance, take the following example:

  • Node A is within VLAN 1234 and subnet 10.144.90.64/26
  • Node B is within VLAN 1234 and subnet 10.144.3.64/29

On linux, you'd do the following to add the necessary routes:

  • Node A # route add -net 10.144.3.64 netmask 255.255.255.248 dev eth0
  • Node B # route add -net 10.144.90.64 netmask 255.255.255.192 dev eth0

If you do this for each subnet, communication will be possible without VLAN Spanning enabled.