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What are the current limits for the number of tenants networks for VLAN and GRE in Neutron?

asked 2013-09-26 09:24:51 -0600

Bart van den Heuvel gravatar image

updated 2013-09-26 17:34:53 -0600

smaffulli gravatar image

When planning for a scalable solution, one that scales up to thousands of tenant networks, which should i choose? GRE or VLAN. And what are the theoretical limits? Are there any changes between Grizzly and Havana?

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answered 2013-09-27 01:06:01 -0600

Hrushi gravatar image

VLAN = 4096 ; 1.802.1Q has a 12-bit VLAN ID field, which has a theoretical limit of 212=4096 tags

GRE - there may be factors such as memory constraints that will place practical limits on how many tunnels you can support. But there is also a hard limit on the number of tunnels that you can configure. That limit is based on the limitation of the number of IDBs supported by your router. The IDB is the Interface Descriptor Block and each interface (physical, or tunnel, or loopback, or whatever) requires an IDB. The number of IDBs will vary by platform and sometimes by release level of the code that you are running. You can use the privileged command show idb to see what the limitation is on your router. On the 1841 router that I just checked the limit on IDB is 1200 (which is a pretty large number - I believe that you would encounter other limits on performance or on size of configuration before you exhaust the IDB limit).

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Many switches do not support more than 1,000 unique VLAN IDs. Check your specs for the number of VLAN IDs your switch supports.

A.Richards gravatar imageA.Richards ( 2013-12-05 12:42:03 -0600 )edit
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answered 2017-12-29 02:18:06 -0600

See Redhat site for actual limits;

Openstack Limits

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Asked: 2013-09-26 09:24:51 -0600

Seen: 1,295 times

Last updated: Dec 29 '17