diff --git a/isisd/isis_circuit.h b/isisd/isis_circuit.h
new file mode 100644
index 0000000..7163c5b
--- /dev/null
+++ b/isisd/isis_circuit.h
@@ -0,0 +1,158 @@
+/*
+ * IS-IS Rout(e)ing protocol - isis_circuit.h
+ *
+ * Copyright (C) 2001,2002   Sampo Saaristo
+ *                           Tampere University of Technology      
+ *                           Institute of Communications Engineering
+ *
+ * This program is free software; you can redistribute it and/or modify it 
+ * under the terms of the GNU General Public Licenseas published by the Free 
+ * Software Foundation; either version 2 of the License, or (at your option) 
+ * any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc., 
+ * 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#ifndef ISIS_CIRCUIT_H
+#define ISIS_CIRCUIT_H
+
+#define CIRCUIT_MAX 255
+
+struct password {
+  struct password *next;
+  int               len;
+  u_char          *pass;
+};
+
+struct metric {
+  u_char metric_default;
+  u_char metric_error;
+  u_char metric_expense;
+  u_char metric_delay;
+};
+
+struct isis_bcast_info {
+  u_char snpa [ETH_ALEN];                  /* SNPA of this circuit */
+  char run_dr_elect[2];                    /* Should we run dr election ? */
+  struct thread *t_run_dr[2];              /* DR election thread */
+  struct thread *t_send_lan_hello[2];      /* send LAN IIHs in this thread */
+  struct list *adjdb[2];                   /* adjacency dbs */
+  struct list *lan_neighs[2];              /* list of lx neigh snpa */
+  char is_dr[2];                           /* Are we level x DR ? */
+  u_char l1_desig_is[ISIS_SYS_ID_LEN + 1]; /* level-1 DR */
+  u_char l2_desig_is[ISIS_SYS_ID_LEN + 1]; /* level-2 DR */
+  struct thread *t_refresh_pseudo_lsp[2];  /* refresh pseudo-node LSPs */
+  int pad_hellos;                          /* add padding to Hello PDUs ? */
+  u_char priority[2];                      /* l1/2 IS Priority */
+};
+
+struct isis_p2p_info {
+  struct isis_adjacency    *neighbor;
+  struct thread *t_send_p2p_hello;         /* send P2P IIHs in this thread  */
+};
+
+struct isis_circuit {
+  int state;
+  u_char circuit_id;             /* l1/l2 p2p/bcast CircuitID */
+  struct isis_area *area;        /* back pointer to the area */
+  struct interface *interface;   /* interface info from z */
+  int fd;                        /* IS-IS l1/2 socket */
+  struct nlpids nlpids;    
+  /*
+   * Threads
+   */
+  struct thread *t_read;
+  struct thread *t_send_csnp[2];
+  struct thread *t_send_psnp[2];
+  struct list *lsp_queue;        /* LSPs to be txed (both levels) */
+  /* there is no real point in two streams, just for programming kicker */
+  int (* rx) (struct isis_circuit *circuit, u_char *ssnpa);
+  struct stream *rcv_stream;     /* Stream for receiving */
+  int (* tx) (struct isis_circuit *circuit, int level);
+  struct stream *snd_stream;     /* Stream for sending */
+  int idx;                       /* idx in S[RM|SN] flags */
+#define CIRCUIT_T_BROADCAST  0 
+#define CIRCUIT_T_P2P        1
+#define CIRCUIT_T_STATIC_IN  2
+#define CIRCUIT_T_STATIC_OUT 3
+#define CIRCUIT_T_DA         4
+  int        circ_type;          /* type of the physical interface */
+  union {
+    struct isis_bcast_info bc;
+    struct isis_p2p_info p2p;
+  } u;
+  char ext_domain;               /* externalDomain   (boolean) */
+  /* 
+   * Configurables 
+   */
+  struct isis_passwd passwd;      /* Circuit rx/tx password */
+  long lsp_interval;            
+  int manual_l2_only;             /* manualL2OnlyMode (boolean) */
+  int circuit_is_type;            /* circuit is type == level of circuit
+                                   * diffrenciated from circuit type (media) */
+  u_int32_t hello_interval[2];    /* l1HelloInterval in msecs */
+  u_int16_t hello_multiplier[2];  /* l1HelloMultiplier */
+  u_int16_t csnp_interval[2];     /* level-1 csnp-interval in seconds */
+  u_int16_t psnp_interval[2];     /* level-1 psnp-interval in seconds */
+  struct metric metrics[2];       /* l1XxxMetric */
+  struct password *c_rx_passwds;  /* circuitReceivePasswords */
+  struct password *c_tc_passwd;   /* circuitTransmitPassword */
+  int ip_router;                  /* Route IP ? */
+  struct list *ip_addrs;          /* our IP addresses */
+#ifdef HAVE_IPV6
+  int ipv6_router;                /* Route IPv6 ? */
+  struct list *ipv6_link;         /* our link local IPv6 addresses */
+  struct list *ipv6_non_link;     /* our non-link local IPv6 addresses */
+#endif /* HAVE_IPV6 */
+  /* 
+   * RFC 2973 IS-IS Mesh Groups 
+   */
+#define MESH_INACTIVE 0
+#define MESH_BLOCKED  1
+#define MESH_SET      2
+  int mesh_enabled;               /* meshGroupEnabled */
+  u_int16_t mesh_group;           /* meshGroup */
+  u_int16_t upadjcount[2];
+  /*
+   * Counters as in 10589--11.2.5.9
+   */
+  u_int32_t adj_state_changes;    /* changesInAdjacencyState */
+  u_int32_t init_failures;        /* intialisationFailures */
+  u_int32_t ctrl_pdus_rxed;       /* controlPDUsReceived */
+  u_int32_t ctrl_pdus_txed;       /* controlPDUsSent */
+  u_int32_t desig_changes[2];     /* lanLxDesignatedIntermediateSystemChanges*/
+  u_int32_t rej_adjacencies;      /* rejectedAdjacencies */
+};
+
+
+void                 isis_circuit_init        (void);
+struct isis_circuit *isis_circuit_new         (void);
+struct isis_circuit *circuit_lookup_by_ifp    (struct interface *ifp, 
+                                               struct list *list);
+struct isis_circuit *circuit_scan_by_ifp      (struct interface *ifp);
+void                 isis_circuit_del         (struct isis_circuit *circuit);
+void                 isis_circuit_configure   (struct isis_circuit *circuit, 
+                                               struct isis_area *area);
+void                 isis_circuit_up          (struct isis_circuit *circuit);
+void                 isis_circuit_deconfigure (struct isis_circuit *circuit, 
+                                               struct isis_area *area);
+
+int                  isis_circuit_destroy     (struct isis_circuit *circuit);
+void                 isis_circuit_if_add      (struct isis_circuit *circuit,
+                                               struct interface *ifp);
+void                 isis_circuit_if_del      (struct isis_circuit *circuit);
+void                 circuit_update_nlpids    (struct isis_circuit *circuit);
+void                 isis_circuit_update_params (struct isis_circuit *circuit,
+                                                 struct interface *ifp);
+void                 isis_circuit_add_addr (struct isis_circuit *circuit, 
+                                            struct connected *conn);
+void                 isis_circuit_del_addr (struct isis_circuit *circuit, 
+                                            struct connected *conn);
+#endif /* _ZEBRA_ISIS_CIRCUIT_H */