yahoo-eng-team team mailing list archive

[LIU Yulong <yulong@xxxxxxxxxxxxx>]

Public bug reported:

The neutron DR agent only advertise floating IP routes as destination(floating IP/32) - next_hop(gateway IP).
Such routes may cause link unreachable in a layer 3 isolated multi-AZ network environment.

For instances:
ISP1 - DC1
ISP2 - DC2
ISP3 - DC3


For the floating IPs, we let all the ISP to advise the IP range, such as 172.16.1.0/24.
And each DC is layer 3 isolated in a separate AZ managed by one neutron deployment.

So for a floating IP (172.16.1.10) bgp route will be:
+-----------------+--------------+
| destination     | next_hop     |
+-----------------+--------------+
| 172.16.1.10/32      | 172.16.1.2      |
+-----------------+--------------+

We use more than one DR agent to advise that route to all DC physic device (router).
Then assuming that 172.16.1.10 is served at DC1. Some incoming traffic from DC2 or DC3 now does
not know how to route the 172.16.1.10, because the 172.16.1.2 is stranger to them, aka link unreachable.

So advising the gateway routes may be needed in such scenario.

** Affects: neutron
     Importance: Undecided
         Status: New

-- 
You received this bug notification because you are a member of Yahoo!
Engineering Team, which is subscribed to neutron.
https://bugs.launchpad.net/bugs/1609296

Title:
  BGP: multiple AZ neutron env has no routes to gateway IPs

Status in neutron:
  New

Bug description:
  The neutron DR agent only advertise floating IP routes as destination(floating IP/32) - next_hop(gateway IP).
  Such routes may cause link unreachable in a layer 3 isolated multi-AZ network environment.

  For instances:
  ISP1 - DC1
  ISP2 - DC2
  ISP3 - DC3

  
  For the floating IPs, we let all the ISP to advise the IP range, such as 172.16.1.0/24.
  And each DC is layer 3 isolated in a separate AZ managed by one neutron deployment.

  So for a floating IP (172.16.1.10) bgp route will be:
  +-----------------+--------------+
  | destination     | next_hop     |
  +-----------------+--------------+
  | 172.16.1.10/32      | 172.16.1.2      |
  +-----------------+--------------+

  We use more than one DR agent to advise that route to all DC physic device (router).
  Then assuming that 172.16.1.10 is served at DC1. Some incoming traffic from DC2 or DC3 now does
  not know how to route the 172.16.1.10, because the 172.16.1.2 is stranger to them, aka link unreachable.

  So advising the gateway routes may be needed in such scenario.

To manage notifications about this bug go to:
https://bugs.launchpad.net/neutron/+bug/1609296/+subscriptions