Limit the supported tunnel types to Geneve and STT on hypervisors, and
VXLAN, Geneve, and STT on gateways. This commit adds "DESIGN.md" that
describes the reasoning.
Signed-off-by: Justin Pettit <jpet...@nicira.com>
---
ovn/TODO | 4 --
ovn/controller/ovn-controller.8.xml | 6 ++-
ovn/ovn-architecture.7.xml | 54 +++++++++++++++++++++++++++++++++++
ovn/ovn-sb.ovsschema | 4 ++-
ovn/ovn-sb.xml | 5 ++-
tutorial/ovs-sandbox | 2 +-
6 files changed, 65 insertions(+), 10 deletions(-)
diff --git a/ovn/TODO b/ovn/TODO
index 41f4d91..209a315 100644
--- a/ovn/TODO
+++ b/ovn/TODO
@@ -91,10 +91,6 @@
** ovn-controller parameters and configuration.
-*** Tunnel encapsulation to publish.
-
- Default: VXLAN? Geneve?
-
*** SSL configuration.
Can probably get this from Open_vSwitch database.
diff --git a/ovn/controller/ovn-controller.8.xml
b/ovn/controller/ovn-controller.8.xml
index 5d4c595..e1cb6a2 100644
--- a/ovn/controller/ovn-controller.8.xml
+++ b/ovn/controller/ovn-controller.8.xml
@@ -97,8 +97,10 @@
<p>
<code>external_ids:ovn-encap-type</code> specifies the
encapsulation type that a chassis should use to connect to
- this node. Examples include <code>geneve</code>,
- <code>vxlan</code>, and <code>stt</code>.
+ this node. Supported tunnel types for connecting
+ hypervisors are <code>geneve</code> and <code>stt</code>.
+ Gateways may use <code>geneve</code>, <code>vxlan</code>,
+ or <code>stt</code>.
</p>
</li>
<li>
diff --git a/ovn/ovn-architecture.7.xml b/ovn/ovn-architecture.7.xml
index f1dfa5f..500ff39 100644
--- a/ovn/ovn-architecture.7.xml
+++ b/ovn/ovn-architecture.7.xml
@@ -575,4 +575,58 @@
to reflect the update.
</li>
</ol>
+
+ <h1>Design Decisions</h1>
+
+ <h2>Supported Tunnel Encapsulations</h2>
+
+ <p>
+ For connecting hypervisors, the only supported tunnel encapsulations
+ are Geneve and STT. We have limited support to these encapsulations
+ for the following reasons:
+ </p>
+
+ <ul>
+ <li>
+ <p>
+ They support large amounts of metadata. In addition to
+ specifying the logical switch, we will likely want to indicate
+ the logical source port and where we are in the logical
+ pipeline. Geneve supports a 24-bit VNI field and TLV-based
+ extensions. The header of STT includes a 64-bit context id.
+ </p>
+ </li>
+
+ <li>
+ <p>
+ They use randomized UDP or TCP source ports that allows
+ efficient distribution among multiple paths in environments that
+ use ECMP in their underlay.
+ </p>
+ </li>
+
+ <li>
+ <p>
+ NICs are available that accelerate encapsulation and decapsulation.
+ </p>
+ </li>
+ </ul>
+
+ <p>
+ Due to its flexibility, the preferred encapsulation between
+ hypervisors is Geneve. Some environments may want to use STT for
+ performance reasons until the NICs they use support hardware offload
+ of Geneve.
+ </p>
+
+ <p>
+ For connecting to gateways, the only supported tunnel encapsulations
+ are VXLAN, Geneve, and STT. While support for Geneve is becoming
+ available for TOR (top-of-rack) switches, VXLAN is far more common.
+ Currently, gateways have a feature set that matches the capabilities
+ as defined by the VTEP schema, so fewer bits of metadata are
+ necessary. In the future, gateways that do not support
+ encapsulations with large amounts of metadata may continue to have a
+ reduced feature set.
+ </p>
</manpage>
diff --git a/ovn/ovn-sb.ovsschema b/ovn/ovn-sb.ovsschema
index 9fd5363..363e664 100644
--- a/ovn/ovn-sb.ovsschema
+++ b/ovn/ovn-sb.ovsschema
@@ -17,7 +17,9 @@
"indexes": [["name"]]},
"Encap": {
"columns": {
- "type": {"type": "string"},
+ "type": {"type": {"key": {
+ "type": "string",
+ "enum": ["set", ["geneve", "stt", "vxlan"]]}}},
"options": {"type": {"key": "string",
"value": "string",
"min": 0,
diff --git a/ovn/ovn-sb.xml b/ovn/ovn-sb.xml
index 29a1c88..2afc9a1 100644
--- a/ovn/ovn-sb.xml
+++ b/ovn/ovn-sb.xml
@@ -166,8 +166,9 @@
<column name="type">
The encapsulation to use to transmit packets to this chassis.
- Examples include <code>geneve</code>, <code>vxlan</code>, and
- <code>stt</code>.
+ Hypervisors must use either <code>geneve</code> or
+ <code>stt</code>. Gateways may use <code>vxlan</code>,
+ <code>geneve</code>, or <code>stt</code>.
</column>
<column name="options">
diff --git a/tutorial/ovs-sandbox b/tutorial/ovs-sandbox
index 8aa2ddd..1520cb7 100755
--- a/tutorial/ovs-sandbox
+++ b/tutorial/ovs-sandbox
@@ -289,7 +289,7 @@ rungdb $gdb_vswitchd ovs-vswitchd --detach --no-chdir
--pidfile -vconsole:off --
if $ovn; then
ovs-vsctl set open .
external-ids:system-id=56b18105-5706-46ef-80c4-ff20979ab068
ovs-vsctl set open . external-ids:ovn-remote=unix:"$sandbox"/db.sock
- ovs-vsctl set open . external-ids:ovn-encap-type=vxlan
+ ovs-vsctl set open . external-ids:ovn-encap-type=geneve
ovs-vsctl set open . external-ids:ovn-encap-ip=127.0.0.1
ovs-vsctl add-br br-int
--
1.7.5.4
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