Merge remote-tracking branch 'origin/cmaster-next' into vtysh-grammar

1 files changed, 20 insertions, 0 deletions

diff --git a/ospfd/ospf_packet.c b/ospfd/ospf_packet.c
index 399a558a0d..b7ef24409e 100644
--- a/ospfd/ospf_packet.c
+++ b/ospfd/ospf_packet.c
@@ -49,6 +49,26 @@
 #include "ospfd/ospf_flood.h"
 #include "ospfd/ospf_dump.h"
 
+/*
+ * OSPF Fragmentation / fragmented writes
+ *
+ * ospfd can support writing fragmented packets, for cases where
+ * kernel will not fragment IP_HDRINCL and/or multicast destined
+ * packets (ie TTBOMK all kernels, BSD, SunOS, Linux). However,
+ * SunOS, probably BSD too, clobber the user supplied IP ID and IP
+ * flags fields, hence user-space fragmentation will not work.
+ * Only Linux is known to leave IP header unmolested.
+ * Further, fragmentation really should be done the kernel, which already
+ * supports it, and which avoids nasty IP ID state problems.
+ *
+ * Fragmentation of OSPF packets can be required on networks with router
+ * with many many interfaces active in one area, or on networks with links
+ * with low MTUs.
+ */
+#ifdef GNU_LINUX
+#define WANT_OSPF_WRITE_FRAGMENT
+#endif
+
 /* Packet Type String. */
 const struct message ospf_packet_type_str[] =
 {