pespin has uploaded this change for review.
ASP loadsharing: Normal ASP distribution regardless of active state
Before this patch, the normal ASP for a given loadshare eSLS entry (seed)
would only be filled in with active ASPs.
That means that if eg. N ASPs are configured but only 1 is successfully
activated upon startup and a lot of traffic happens, the full eSLS will
be filled with that ASP, and as a result all traffic will be sent to
that ASP, with the exception during the time that ASP is inactive.
Instead, we want to populate the eSLS table with Normal ASP field
properly distributed over all ASPs. If a given ASP is not active at that
time, then simply pick an Alternative ASP during that time.
Change-Id: I2064fe89bac2d3bd86fee544a64ab21417e1c368
---
M src/osmo_ss7_as.c
M src/ss7_as.h
2 files changed, 46 insertions(+), 10 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/libosmo-sigtran refs/changes/07/39707/1
diff --git a/src/osmo_ss7_as.c b/src/osmo_ss7_as.c
index 35a2650..22fcb14 100644
--- a/src/osmo_ss7_as.c
+++ b/src/osmo_ss7_as.c
@@ -304,6 +304,33 @@
return asp;
}
+/* Pick an ASP serving AS in a round-robin fashion.
+ * During Loadshare eSLS table generation we want to pick Normal ASP
+ * in a distributed fashion, regardless of active state (Alternative ASP will
+ * be picked up temporarily later on if needed).
+ * Morevoer, we must use a different index from the "active"
+ * ss7_as_select_asp_roundrobin() below, in order to avoid tainting the
+ * distribution. */
+static struct osmo_ss7_asp *ss7_as_assign_asp_roundrobin(struct osmo_ss7_as *as)
+{
+ struct osmo_ss7_asp *asp;
+ unsigned int i;
+ unsigned int first_idx;
+
+ first_idx = (as->cfg.last_asp_idx_assigned + 1) % ARRAY_SIZE(as->cfg.asps);
+ i = first_idx;
+ do {
+ asp = as->cfg.asps[i];
+ if (asp)
+ break;
+ i = (i + 1) % ARRAY_SIZE(as->cfg.asps);
+ } while (i != first_idx);
+ as->cfg.last_asp_idx_assigned = i;
+
+ return asp;
+}
+
+/* Pick an active ASP serving AS in a round-robin fashion, to send a message to. */
static struct osmo_ss7_asp *ss7_as_select_asp_roundrobin(struct osmo_ss7_as *as)
{
struct osmo_ss7_asp *asp;
@@ -397,17 +424,24 @@
/* No current ASP available, try to find a new current ASP: */
- /* No normal route selected yet: */
+ /* No normal route assigned yet: */
if (!aeslse->normal_asp) {
- asp = ss7_as_select_asp_roundrobin(as);
- /* Either a normal route was selected or none found: */
+ /* Establish a Normal ASP, regardless of active state: */
+ asp = ss7_as_assign_asp_roundrobin(as);
+ /* No ASP found for Normal ASP, regardless of state... */
+ if (!asp)
+ return NULL;
aeslse->normal_asp = asp;
- if (asp)
- LOGPAS(as, DLSS7, LOGL_DEBUG, "Tx Loadshare: OPC=%u=%s,SLS=%u -> eSLS=%u: "
- "picked Normal ASP '%s' round-robin style\n",
- mtp->opc, osmo_ss7_pointcode_print(as->inst, mtp->opc),
- mtp->sls, as_ext_sls, asp->cfg.name);
- return asp;
+ LOGPAS(as, DLSS7, LOGL_DEBUG, "Tx Loadshare: OPC=%u=%s,SLS=%u -> eSLS=%u: "
+ "picked Normal ASP '%s' round-robin style\n",
+ mtp->opc, osmo_ss7_pointcode_print(as->inst, mtp->opc),
+ mtp->sls, as_ext_sls, aeslse->normal_asp->cfg.name);
+ if (osmo_ss7_asp_active(aeslse->normal_asp)) {
+ /* Found active Normal Route: */
+ return aeslse->normal_asp;
+ }
+ /* Normal ASP was assigned, but it is not active, fall-through
+ * below to attempt transmission through Alternative ASP: */
}
/* Normal ASP unavailable and no alternative ASP (or unavailable too).
diff --git a/src/ss7_as.h b/src/ss7_as.h
index c4dfdf6..13592e9 100644
--- a/src/ss7_as.h
+++ b/src/ss7_as.h
@@ -108,7 +108,9 @@
} pc_override;
struct osmo_ss7_asp *asps[16];
- uint8_t last_asp_idx_sent; /* used for load-sharing traffic mode (round robin implementation) */
+ /* used for load-sharing traffic mode (round robin implementation) */
+ uint8_t last_asp_idx_assigned;
+ uint8_t last_asp_idx_sent;
struct {
/* How many bits from ITU SLS field (starting from least-significant-bit)
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