Thanks for the patch.
I'm not sure in what circumstances a broadcast domain would be shared
among deployments. I tend to think of OVN L2 networks as contained.
But I guess this patch was written for a reason, so it must be common
enough.
I can see at least two possible routes here:
- The current one, in which there is a default MAC_ADDR_PREFIX. Two
OVN deployments cannot coexist using MACAM, supposing they somehow
share a broadcast domain, unless at least one of them manually
selects an alternate MAC prefix. This may be desirable if it is
important that the default MAC prefix 0A-00-00 be recognizable.
- An alternative would be for every OVN deployment to automatically
select a random MAC address prefix. When ovn-northd starts, it
would read the MAC address prefix out of NB_Global, and if there
isn't one, generate one randomly and store it into NB_Global.
Then there would be fewer pitfalls in setting up multiple
deployments.
I am OK with the one currently proposed, but I want to make sure that
the other approach was at least considered.
On Fri, Oct 26, 2018 at 04:15:27PM -0400, Mark Michelson wrote:
> Looks good, Lorenzo,
>
> Just to reaaffirm my previous ack:
>
> Acked-by: Mark Michelson <[email protected]>
>
> On 10/26/2018 12:20 PM, Lorenzo Bianconi wrote:
> >Add the possibility to specify a given mac address prefix for
> >dynamically generated mac address. Mac address prefix can be
> >specified in nbdb NB_Global table, options:mac_prefix=<mac_prefix>
> >This patch fix a possible issue of L2 address duplication if
> >multiple OVN deployments share a single broadcast domain
> >
> >Acked-by: Mark Michelson <[email protected]>
> >Signed-off-by: Lorenzo Bianconi <[email protected]>
> >---
> >Changes since v1:
> >- use a global definition for mac_prefix
> >---
> > ovn/northd/ovn-northd.c | 37 ++++++++++++++++++++++++++++++++++---
> > ovn/ovn-nb.xml | 5 +++++
> > tests/ovn.at | 17 +++++++++++++++++
> > 3 files changed, 56 insertions(+), 3 deletions(-)
> >
> >diff --git a/ovn/northd/ovn-northd.c b/ovn/northd/ovn-northd.c
> >index 439651f80..816c72311 100644
> >--- a/ovn/northd/ovn-northd.c
> >+++ b/ovn/northd/ovn-northd.c
> >@@ -68,6 +68,7 @@ static const char *unixctl_path;
> > /* MAC address management (macam) table of "struct eth_addr"s, that holds
> > the
> > * MAC addresses allocated by the OVN ipam module. */
> > static struct hmap macam = HMAP_INITIALIZER(&macam);
> >+static struct eth_addr mac_prefix;
> > #define MAX_OVN_TAGS 4096
> >
> >@@ -922,10 +923,17 @@ ipam_insert_mac(struct eth_addr *ea, bool check)
> > }
> > uint64_t mac64 = eth_addr_to_uint64(*ea);
> >+ uint64_t prefix;
> >+
> >+ if (!eth_addr_is_zero(mac_prefix)) {
> >+ prefix = eth_addr_to_uint64(mac_prefix);
> >+ } else {
> >+ prefix = MAC_ADDR_PREFIX;
> >+ }
> > /* If the new MAC was not assigned by this address management system or
> > * check is true and the new MAC is a duplicate, do not insert it into
> > the
> > * macam hmap. */
> >- if (((mac64 ^ MAC_ADDR_PREFIX) >> 24)
> >+ if (((mac64 ^ prefix) >> 24)
> > || (check && ipam_is_duplicate_mac(ea, mac64, true))) {
> > return;
> > }
> >@@ -1036,7 +1044,11 @@ ipam_get_unused_mac(void)
> > for (i = 0; i < MAC_ADDR_SPACE - 1; i++) {
> > /* The tentative MAC's suffix will be in the interval (1,
> > 0xfffffe). */
> > mac_addr_suffix = ((last_mac + i) % (MAC_ADDR_SPACE - 1)) + 1;
> >- mac64 = MAC_ADDR_PREFIX | mac_addr_suffix;
> >+ if (!eth_addr_is_zero(mac_prefix)) {
> >+ mac64 = eth_addr_to_uint64(mac_prefix) | mac_addr_suffix;
> >+ } else {
> >+ mac64 = MAC_ADDR_PREFIX | mac_addr_suffix;
> >+ }
> > eth_addr_from_uint64(mac64, &mac);
> > if (!ipam_is_duplicate_mac(&mac, mac64, false)) {
> > last_mac = mac_addr_suffix;
> >@@ -1107,7 +1119,15 @@ dynamic_mac_changed(const char *lsp_addresses,
> > }
> > uint64_t mac64 = eth_addr_to_uint64(update->current_addresses.ea);
> >- if ((mac64 ^ MAC_ADDR_PREFIX) >> 24) {
> >+ uint64_t prefix;
> >+
> >+ if (!eth_addr_is_zero(mac_prefix)) {
> >+ prefix = eth_addr_to_uint64(mac_prefix);
> >+ } else {
> >+ prefix = MAC_ADDR_PREFIX;
> >+ }
> >+
> >+ if ((mac64 ^ prefix) >> 24) {
> > return DYNAMIC;
> > } else {
> > return NONE;
> >@@ -7141,6 +7161,17 @@ ovnnb_db_run(struct northd_context *ctx,
> > sbrec_sb_global_set_options(sb, &nb->options);
> > sb_loop->next_cfg = nb->nb_cfg;
> >+ const char *mac_addr_prefix = smap_get(&nb->options, "mac_prefix");
> >+ if (mac_addr_prefix) {
> >+ struct eth_addr addr;
> >+
> >+ memset(&addr, 0, sizeof addr);
> >+ if (ovs_scan(mac_addr_prefix, "%"SCNx8":%"SCNx8":%"SCNx8,
> >+ &addr.ea[0], &addr.ea[1], &addr.ea[2])) {
> >+ mac_prefix = addr;
> >+ }
> >+ }
> >+
> > cleanup_macam(&macam);
> > }
> >diff --git a/ovn/ovn-nb.xml b/ovn/ovn-nb.xml
> >index c0739fe57..f309b3b86 100644
> >--- a/ovn/ovn-nb.xml
> >+++ b/ovn/ovn-nb.xml
> >@@ -102,6 +102,11 @@
> > tunnel interfaces.
> > </column>
> > </group>
> >+
> >+ <column name="options" key="mac_prefix">
> >+ Configure a given OUI to be used as prefix when L2 address is
> >+ dynamically assigned, e.g. <code>00:11:22</code>
> >+ </column>
> > </group>
> > <group title="Connection Options">
> >diff --git a/tests/ovn.at b/tests/ovn.at
> >index 8825beca3..e512f94aa 100644
> >--- a/tests/ovn.at
> >+++ b/tests/ovn.at
> >@@ -5616,6 +5616,23 @@ AT_CHECK([ovn-nbctl get Logical-Switch-Port p41
> >dynamic_addresses], [0],
> > ["f0:00:00:00:10:2b 192.168.1.3"
> > ])
> >+# define a mac address prefix
> >+ovn-nbctl ls-add sw6
> >+ovn-nbctl --wait=hv set NB_Global . options:mac_prefix="00:11:22:33:44:55"
> >+ovn-nbctl --wait=sb set Logical-Switch sw6
> >other_config:subnet=192.168.100.0/24
> >+for n in $(seq 1 3); do
> >+ ovn-nbctl --wait=sb lsp-add sw6 "p5$n" -- lsp-set-addresses "p5$n"
> >dynamic
> >+done
> >+AT_CHECK([ovn-nbctl get Logical-Switch-Port p51 dynamic_addresses], [0],
> >+ ["00:11:22:00:00:4d 192.168.100.2"
> >+])
> >+AT_CHECK([ovn-nbctl get Logical-Switch-Port p52 dynamic_addresses], [0],
> >+ ["00:11:22:00:00:4e 192.168.100.3"
> >+])
> >+AT_CHECK([ovn-nbctl get Logical-Switch-Port p53 dynamic_addresses], [0],
> >+ ["00:11:22:00:00:4f 192.168.100.4"
> >+])
> >+
> > as ovn-sb
> > OVS_APP_EXIT_AND_WAIT([ovsdb-server])
> >
>
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