diff --git a/isisd/modified/thread.h b/isisd/modified/thread.h
new file mode 100644
index 0000000..c3fac43
--- /dev/null
+++ b/isisd/modified/thread.h
@@ -0,0 +1,141 @@
+/* Thread management routine header.
+ * Copyright (C) 1998 Kunihiro Ishiguro
+ *
+ * This file is part of GNU Zebra.
+ *
+ * GNU Zebra is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * GNU Zebra is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Zebra; see the file COPYING.  If not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.  
+ */
+
+#ifndef _ZEBRA_THREAD_H
+#define _ZEBRA_THREAD_H
+
+#ifdef HAVE_RUSAGE
+#define RUSAGE_T        struct rusage
+#define GETRUSAGE(X)    getrusage (RUSAGE_SELF, X);
+#else
+#define RUSAGE_T        struct timeval
+#define GETRUSAGE(X)    gettimeofday (X, NULL);
+#endif /* HAVE_RUSAGE */
+
+/* Linked list of thread. */
+struct thread_list
+{
+  struct thread *head;
+  struct thread *tail;
+  int count;
+};
+
+/* Master of the theads. */
+struct thread_master
+{
+  struct thread_list read;
+  struct thread_list write;
+  struct thread_list timer;
+  struct thread_list event;
+  struct thread_list ready;
+  struct thread_list unuse;
+  fd_set readfd;
+  fd_set writefd;
+  fd_set exceptfd;
+  unsigned long alloc;
+};
+
+/* Thread itself. */
+struct thread
+{
+  unsigned char type;		/* thread type */
+  struct thread *next;		/* next pointer of the thread */
+  struct thread *prev;		/* previous pointer of the thread */
+  struct thread_master *master;	/* pointer to the struct thread_master. */
+  int (*func) (struct thread *); /* event function */
+  void *arg;			/* event argument */
+  union {
+    int val;			/* second argument of the event. */
+    int fd;			/* file descriptor in case of read/write. */
+    struct timeval sands;	/* rest of time sands value. */
+  } u;
+  RUSAGE_T ru;			/* Indepth usage info.  */
+};
+
+/* Thread types. */
+#define THREAD_READ           0
+#define THREAD_WRITE          1
+#define THREAD_TIMER          2
+#define THREAD_EVENT          3
+#define THREAD_READY          4
+#define THREAD_UNUSED         5
+
+/* Thread yield time.  */
+#define THREAD_YIELD_TIME_SLOT     100 * 1000L /* 100ms */
+
+/* Macros. */
+#define THREAD_ARG(X) ((X)->arg)
+#define THREAD_FD(X)  ((X)->u.fd)
+#define THREAD_VAL(X) ((X)->u.val)
+
+#define THREAD_READ_ON(master,thread,func,arg,sock) \
+  do { \
+    if (! thread) \
+      thread = thread_add_read (master, func, arg, sock); \
+  } while (0)
+
+#define THREAD_WRITE_ON(master,thread,func,arg,sock) \
+  do { \
+    if (! thread) \
+      thread = thread_add_write (master, func, arg, sock); \
+  } while (0)
+
+#define THREAD_TIMER_ON(master,thread,func,arg,time) \
+  do { \
+    if (! thread) \
+      thread = thread_add_timer (master, func, arg, time); \
+  } while (0)
+
+#define THREAD_OFF(thread) \
+  do { \
+    if (thread) \
+      { \
+        thread_cancel (thread); \
+        thread = NULL; \
+      } \
+  } while (0)
+
+#define THREAD_READ_OFF(thread)  THREAD_OFF(thread)
+#define THREAD_WRITE_OFF(thread)  THREAD_OFF(thread)
+#define THREAD_TIMER_OFF(thread)  THREAD_OFF(thread)
+
+/* Prototypes. */
+struct thread_master *thread_master_create ();
+struct thread *thread_add_read (struct thread_master *, 
+				int (*)(struct thread *), void *, int);
+struct thread *thread_add_write (struct thread_master *,
+				 int (*)(struct thread *), void *, int);
+struct thread *thread_add_timer (struct thread_master *,
+				 int (*)(struct thread *), void *, long);
+struct thread *thread_add_timer_msec (struct thread_master *,
+                                       int (*)(struct thread *), void *, long);
+struct thread *thread_add_event (struct thread_master *,
+				 int (*)(struct thread *), void *, int );
+void thread_cancel (struct thread *);
+void thread_cancel_event (struct thread_master *, void *);
+
+struct thread *thread_fetch (struct thread_master *, struct thread *);
+struct thread *thread_execute (struct thread_master *,
+			       int (*)(struct thread *), void *, int);
+void thread_call (struct thread *);
+unsigned long thread_timer_remain_second (struct thread *);
+
+#endif /* _ZEBRA_THREAD_H */