Restore SVP_R_ROUTE_REQ, and all that goes with it.
Interpret sl3a_uport == 0 in SVP_R_VL3_ACK to indicate the VL3 IP is a next-hop router.

*** 59,70 ****
          SVP_R_LOG_REQ           = 0x09,
          SVP_R_LOG_ACK           = 0x0A,
          SVP_R_LOG_RM            = 0x0B,
          SVP_R_LOG_RM_ACK        = 0x0C,
          SVP_R_SHOOTDOWN         = 0x0D,
!         SVP_R_REMOTE_VL3_REQ    = 0x0E,
!         SVP_R_REMOTE_VL3_ACK    = 0x0F
  } svp_op_t;
  
  typedef enum svp_status {
          SVP_S_OK        = 0x00, /* Everything OK */
          SVP_S_FATAL     = 0x01, /* Fatal error, close connection */
--- 59,70 ----
          SVP_R_LOG_REQ           = 0x09,
          SVP_R_LOG_ACK           = 0x0A,
          SVP_R_LOG_RM            = 0x0B,
          SVP_R_LOG_RM_ACK        = 0x0C,
          SVP_R_SHOOTDOWN         = 0x0D,
!         SVP_R_ROUTE_REQ         = 0x0E,
!         SVP_R_ROUTE_ACK         = 0x0F
  } svp_op_t;
  
  typedef enum svp_status {
          SVP_S_OK        = 0x00, /* Everything OK */
          SVP_S_FATAL     = 0x01, /* Fatal error, close connection */
*** 72,82 ****
          SVP_S_BADL3TYPE = 0x03, /* Unknown svp_vl3_type_t */
          SVP_S_BADBULK   = 0x04  /* Unknown svp_bulk_type_t */
  } svp_status_t;
  
  /*
!  * A client issues the SVP_R_VL2_REQ whenever it needs to perform a VLS->UL3
   * lookup. Requests have the following structure:
   */
  typedef struct svp_vl2_req {
          uint8_t         sl2r_mac[ETHERADDRL];
          uint8_t         sl2r_pad[2];
--- 72,82 ----
          SVP_S_BADL3TYPE = 0x03, /* Unknown svp_vl3_type_t */
          SVP_S_BADBULK   = 0x04  /* Unknown svp_bulk_type_t */
  } svp_status_t;
  
  /*
!  * A client issues the SVP_R_VL2_REQ whenever it needs to perform a VL2->UL3
   * lookup. Requests have the following structure:
   */
  typedef struct svp_vl2_req {
          uint8_t         sl2r_mac[ETHERADDRL];
          uint8_t         sl2r_pad[2];
*** 122,159 ****
          uint16_t        sl3a_uport;
          uint8_t         sl3a_uip[16];
  } svp_vl3_ack_t;
  
  /*
-  * A client issues the SVP_R_REMOTE_VL3_REQ for a far-remote (cross-DC) VL3 IP
-  * address.  The server may take longer because it may query cross-DC to get
-  * the answer for our response.
-  */
- typedef struct svp_rvl3_req {
-         uint8_t         srl3r_srcip[16];
-         uint8_t         srl3r_dstip[16];
-         uint32_t        srl3r_type;     /* Same as SVP_R_VL3_REQ */
-         uint32_t        srl3r_vnetid;
-         uint16_t        srl3r_vlan;
-         uint16_t        srl3r_pad;      /* XXX KEBE ASKS, necessary? */
- } svp_rvl3_req_t;
- 
- /*
-  * The remote-VL3 response contains more than the regular VL3 one, because
-  * overlay needs to rewrite the MAC header completely.
-  */
- typedef struct svp_rvl3_ack {
-         uint32_t        srl3a_status;
-         uint8_t         srl3a_dstmac[ETHERADDRL]; /* MAC of the target. */
-         uint8_t         srl3a_srcmac[ETHERADDRL]; /* MAC of the target's rtr */
-         uint16_t        srl3a_vlanid;
-         uint16_t        srl3a_uport;
-         uint32_t        srl3a_dcid;     /* Remote Data Center ID. */
-         uint8_t         srl3a_uip[16];
- } svp_rvl3_ack_t;
- 
- /*
   * SVP_R_BULK_REQ requests a bulk dump of data. Currently we have two kinds of
   * data tables that we need to dump: VL3->VL2 mappings and VL2->UL3 mappings.
   * The kind that we want is indicated using the svbr_type member.
   */
  typedef enum svp_bulk_type {
--- 122,131 ----
*** 259,268 ****
--- 231,272 ----
          uint8_t         svsd_mac[ETHERADDRL];
          uint8_t         svsd_pad[2];
          uint32_t        svsd_vnetid;
  } svp_shootdown_t;
  
+ /*
+  * A route-request (SVP_R_ROUTE_REQ) queries the local SVP server to get a
+  * far-remote (i.e. another Triton Data Center, nee. SDC) SVP server for
+  * far-remote networks.  Modern overlay modules will request IP destinations
+  * for remote-Triton networks, but they must know how to reach the
+  * remote-Triton SVP server.
+  */
+ typedef struct svp_route_req {
+         uint32_t        srr_vnetid;     /* Requester's vnet ID. */
+         uint16_t        srr_vlan;       /* Requester's VLAN ID. */
+         uint16_t        srr_pad;        /* Zero on xmit, ignore on receipt. */
+         uint8_t         srr_srcip[16];  /* VL3 Source IP. */
+         uint8_t         srr_dstip[16];  /* VL3 Destination IP. */
+ } svp_route_req_t;
+ 
+ /*
+  * The far-remote Triton Data Center will answer with the requisite information
+  * to send overlay packets to the appropriate far-remote CNs.
+  */
+ typedef struct svp_route_ack {
+         uint32_t        sra_status;     /* Status. */
+         uint32_t        sra_dcid;       /* Far-remote Data Center ID. */
+         uint32_t        sra_vnetid;     /* Far-remote vnet ID. */
+         uint16_t        sra_vlan;       /* Far-remote VLAN ID. */
+         uint16_t        sra_port;       /* Destination UL3 port. */
+         uint8_t         sra_ip[16];     /* Destination UL3 address. */
+         uint8_t sra_srcmac[ETHERADDRL]; /* Far-remote VL2 source. */
+         uint8_t sra_dstmac[ETHERADDRL]; /* Far-remote VL2 dest. */
+         uint8_t         sra_src_pfx;    /* Far-remote VL3 source prefix */
+         uint8_t         sra_dst_pfx;    /* Far-remote VL3 dest. prefix */
+ } svp_route_ack_t;
+ 
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* _LIBVARPD_SVP_PROT_H */