Store remote 4 octet AS path value.

Change-Id: Ifccc777c48392effb0ab86298115c9abb4fe5e48

@@ -335,6 +335,7 @@ final class BgpOpen {
                     }
                     long as4Number = message.readUnsignedInt();
                     // TODO: Implement support for 4-octet AS Numbers
+                    bgpSession.setRemoteAs4Octet(as4Number);
                     log.debug("BGP RX OPEN Capability:  AS4 Number = {}",
                               as4Number);
                     break;

@@ -59,6 +59,7 @@ public class BgpSession extends SimpleChannelHandler {
     private Ip4Address remoteIp4Address;        // Peer IPv4 address
     private int remoteBgpVersion;               // 1 octet
     private long remoteAs;                      // 2 octets
+    private long remoteAs4Octet;                // 4 octets
     private long remoteHoldtime;                // 2 octets
     private Ip4Address remoteBgpId;             // 4 octets -> IPv4 address
     private boolean remoteIpv4Unicast;          // Peer IPv4/UNICAST AFI/SAFI
@@ -191,6 +192,15 @@ public class BgpSession extends SimpleChannelHandler {
     }
 
     /**
+     * Sets the BGP session remote 4 octet AS number.
+     *
+     * @param remoteAs4Octet the BGP session remote 4 octet AS number to set
+     */
+    void setRemoteAs4Octet(long remoteAs4Octet) {
+        this.remoteAs4Octet = remoteAs4Octet;
+    }
+
+    /**
      * Gets the BGP session remote Holdtime.
      *
      * @return the BGP session remote Holdtime