Abstract:
A host router is logically partitioned into virtual router domains that manage independent processes and routing application copies but share a common operating system. Each v-net manages an independent set of sockets and host router interfaces, each associated with only one v-net at one time, but interchangeably repartitionable Traffic is removed from an interface during repartitioning. Duplicate arrays of global variables copied to each v-net are accessed by macro references. A v-net facility can separate route tables used internally from the externally visible route tables and can avoid conflicts between internal and external IP addresses that share the same identifier. For example a common FreeBSD operating system supports a dynamic routing protocol (DRP) application. Each v-net runs an independent copy of the DRP software and is logically independent. A failure in one DRP copy does not adversely affect other copies.

Description:
BACKGROUND  
         [0001]    Transmission Control Protocol (TCP) is an underlying connection protocol that is typically used for all types of network communication. A route is essentially the mapping of an IP address to an egress port of a router. Different network routers set up connections with their peer routers using operating systems, for example Border Gateway Protocol (BGP) over TCP or OSPF (Open Shortest Path First) over Internet Protocol (IP) to determine that they get route information from their peers, allowing them to construct essentially an internal map of the network and to select the route that they should use, as well as verification that their peers are operating correctly. This is accomplished by sending various keep-alive packets back and forth to make sure that their peers are still correctly functioning. Routes are used internally within a router, for example a Master Control Processor (MCP) communicates through an Ethernet control network (CNET) within a router with the shelf control processors, each of which have individual IP addresses. Processes including routing applications, for example Dynamic Routing Protocol (DRP), run on these operating systems. Sockets are end points of communication associated with a process. A particular process can have more than one socket.  
           [0002]    In a router with a large number of ports, for example 320 ports, that communicates with peer routers, it is advantageous to subdivide that single large router logically into several smaller virtual routers, each of which can be individually configured. There can be separate departments in a large company, or an Internet provider wanting to partition a large router among clients, for example for security reasons. However, previous implementations of subdividing routers having large numbers of ports have been cumbersome.  
         SUMMARY OF THE INVENTION  
         [0003]    The present invention is directed to a system and method which logically partition a host router into virtual router domains that run independent processes and routing application copies but share a common operating system. Each v-net domain manages an independent set of interface ports. Each process manages an independent set of sockets.  
           [0004]    In some embodiments a v-net domain architecture is used to partition a host router. Some v-net domains support virtual routers, whereas other v-net domains support only internal router processes and management applications. Thus, not every v-net domain supports a virtual router. A single v-net domain can support more than one process. A v-net facility can advantageously separate route tables used internally from the externally visible routes, making network management easier and more transparent. With separate v-net domains for example, the IP address of an internal shelf control processor does not conflict with the same IP address that is assigned elsewhere on the Internet. In a v-net implementation, duplicate arrays of global variables are instantiated in each virtual router domain and are accessed by macro references.  
           [0005]    A common FreeBSD operating system running on the MCP supports a dynamic routing protocol (DRP) application. Each new virtual router is independently managed by its own copy of the DRP application for as many virtual routers as exist. If something goes awry in one DRP copy, it does not affect other copies. Each v-net domain manages a separate set of the interfaces associated with the host router, which provide connections to peer routers. For example, if a host router has 320 ports, one v-net domain can manage 120 ports or interfaces, and another v-net domain can manage another 120 ports. All of these ports and interfaces can be interchangeably partitioned. For each Synchronous Optical Network (SONET) port on a line card, there is an interface (IF) data structure in FreeBSD that represents that SONET port. Any interface can be associated with only one v-net at one time, but can be moved among v-nets to reconfigure the host router. Traffic is removed from an interface while it is being moved. At a high level the host router is partitioned, and each partition normally is managed by an independent copy of the DRP software. In an administrative sense, each of these partitions is logically independent.  
           [0006]    Certain activities are still managed across the entire host router, for example failure reporting of hardware in the host router, which is machine specific, and therefore is a resource shared by all of the partitions.  
           [0007]    This partitioning also allows the routes between the individual components such as the line cards and processors internal to a router to be contained in route tables separate from externally visible routes. Partitioning the router also facilitates testing, such that one partition might be used for normal network traffic and another might be used to test for example new software or new network configurations for new types of protocols. Additionally, a degree of redundancy is achieved, such that failure of one partition generally does not adversely affect another partition sharing the same host router.  
           [0008]    Various aspects of the invention are described in co-pending and commonly assigned U.S. application Ser. No. 09/703,057, entitled “System And Method For IP Router With an Optical Core,” filed Oct. 31, 2000, the disclosure of which has been incorporated herein by reference.  
           [0009]    The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0010]    For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:  
         [0011]    [0011]FIG. 1 is a logical diagram illustrating the principles of router virtual networking, according to an embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0012]    In embodiments of the present invention, a host network router is logically partitioned into multiple virtual networking domains sharing a common operating system. FIG. 1 is a logical diagram illustrating the principles of router virtual networking, according to an embodiment of the present invention. In the implementation of FIG. 1, a host router  10  is logically partitioned into v-net domains  12 ,  14 , and  16  that are associated with networking systems. Each v-net  12 ,  14 ,  16  has a unique v-net ID address  13 ,  15 ,  17 , in accordance with network protocols. Host router  10  and each of v-nets  12 ,  14 ,  16  are further logically subdivided into two spaces, shown in FIG. 1 separated horizontally by a solid line, namely a user level  18  and a kernel level  20  of the shared common operating system (OS), for example a version of FreeBSD. The present FreeBSD operating system runs on the host router Master Control Processor (MCP), described for example in U.S. application Ser. No. 09/703,057, entitled “System And Method For IP Router With an Optical Core,” filed Oct. 31, 2000, cited above, the disclosure of which has been incorporated herein by reference, and the dynamic routing protocol (DRP) application software runs on top of FreeBSD.  
         [0013]    An operating system contains within it logical notions called processes  22 - 26 , for example Internet Management Application  22 , DRP  23 ,  25 , or Simple Network Management Protocol (SNMP) agent application  24 ,  26 , running on v-nets  12 ,  14 , and  16 . Different individual v-nets can manage the same, different, single, or multiple processes. V-net domains  14  and  16 , each running DRP and SNMP processes, are virtual routers, whereas v-net domain  12 , running only an internal management application, is not a virtual router. The present FreeBSD operating system supports multiple processes, among which are DRP  23 ,  25 , SNMP  24 ,  26 , and Internal Management Application  22 . Each process occupies some user level space  18  and also some operating system kernel level space  20 . User level space  18  includes the application and the values of all the application variables (not shown in FIG. 1), whereas OS or kernel level space  20  of the process includes internal data that the kernel maintains with each process. Typical examples of internal kernel data include descriptors or descriptions of open files and the ID of the user that owns the process, attributes that are added to each process associated with a particular v-net.  
         [0014]    Among other things associated with a particular v-net are interfaces, for example interfaces  42 - 1  through  42 - 3  associated with v-net  12 . An interface represents for example a particular physical hardware Ethernet card, gigabit Ethernet card, or SONET line card interconnected with a remote router. This allows partitioning of host router interfaces, such that for example interfaces  42 - 1  through  42 - 3  contain v-net ID  13  of v-net  12  with which they are associated. V-net domain  12  maintains an interface list  42 - 0  pointing to interfaces  42 - 1  through  42 - 3 . Similarly v-net domain  14  maintains an interface list  43 - 0  pointing to interfaces  43 - 1  through  43 - 3  carrying v-net ID  15  of v-net domain  14 , and v-net domain  16  maintains an interface list  45 - 0  pointing to interfaces  45 - 1  through  45 - 3  carrying v-net ID  17  of v-net domain  16 .  
         [0015]    Each process  22 - 26  can create sockets, which are end points of communication associated with a process, for example sockets  32 - 1  through  32 - 3  associated with process  22  in v-net domain  12 . A particular process can have more than one socket. Each socket has a v-net ID associated with it, for example sockets  32 - 1  through  32 - 3  each contain v-net ID  13  of v-net  12 . In v-net  12 , management application  22  maintains a descriptor table, for example file descriptor table  32 - 0  of v-net  12 , holding references to sockets  32 - 1  through  32 - 3  and to files, which are each associated with specific application  22 . Similarly, in v-net  14 , DRP application  23  maintains descriptor table  33 - 0 , holding references to sockets  33 - 1  through  33 - 3  and to files associated with application  23 , and SNMP application  24  maintains descriptor table  34 - 0  holding references to sockets  34 - 1  through  34 - 3  and to files associated with application  24 . Likewise in v-net  16 , DRP application  25  maintains descriptor table  35 - 0 , holding references to sockets  35 - 1  through  35 - 3  and to files associated with application  25 , and SNMP application  26  maintains descriptor table  36 - 0  holding references to sockets  36 - 1  through  36 - 3  and to files associated with application  26 .  
         [0016]    Sockets are partitioned basically according to the domain in which communication takes place. Each of the things done to the socket is interpreted in the context of the particular v-net in which the socket is created, and therefore the socket carries that particular v-net identifier. The process has a v-net identifier, because when a process creates a new socket, which it is able to do, each socket that it creates is then created in a process of that v-net identifier. For example, if a process is associated with v-net  0  creates a socket, then that socket is automatically associated with v-net  0 , gets its routing tables from v-net  0 , and can then use all of the interfaces that are assigned to v-net  0 . A process can, however, change its v-net identifier and thereby its v-net association, for example by moving logically from v-net  0  to v-net  1 , and can then create a new socket associated with v-net  1 , which uses routing tables and interfaces of v-net  1 , which are disjoint with the interfaces for v-net  0 .  
         [0017]    Once a socket is created, it cannot be moved to another v-net, but remains in the domain in which it was created. However, a process, by changing its v-net identifier, can then create sockets in multiple domains. Consequently, a process can essentially communicate across domains by creating a socket in each one, but each socket, throughout its existence, is fixed in its original domain. Multiple sockets created by a process are distinctly different from a single socket that is simply interpreted in different ways. For example a single process can create ten distinct sockets in one domain and five distinct sockets in another domain. For example, socket  35 - 4  is created in v-net domain  12  by DRP application  25  and carries v-net ID  13 , although socket  35 - 4  is referenced in descriptor list  35 - 0  of DRP application  25 , which is now in v-net domain  16 . Likewise, socket  33 - 4  is created in v-net domain  12  by DRP application  23  and thus carries v-net ID  13 , although socket  33 - 4  is referenced in descriptor list  33 - 0 , which is now in v-net domain  14 . A socket is destroyed when a process exits or when a process closes down the communication end point represented by that socket. After a socket is destroyed, it is no longer associated with any domain, and the memory associated with it is freed.  
         [0018]    If for example v-net  14  and v-net  16  are two networking domains of host router  10 , and if v-net  14  is a production network carrying live traffic with production code in it, or production network connections carrying real customer traffic, then a socket associated with v-net  14  is operating in that v-net&#39;s space and has routing tables  48  for that v-net to route live traffic. Consequently, if the socket were to select a particular IP address, that IP address would use production routing tables  48 . A different socket in a different v-net  16  is for example used for a small test bed and contains a different set of routing tables  50 . Accordingly, when a message is sent on v-net  16  with an IP address, that IP address is interpreted in the context of v-net  16  running the small test bed.  
         [0019]    Global variables are variables that are accessible to all the various logical contexts or threads of execution that are running concurrently within an operating system. Thus a global variable is not on the stack of a particular thread. Accordingly, all global variables are available to every process that is running within the operating system. Global variables include at least at the top level, for example, the IP address of a machine or a copy of the routing tables so that a process knows where to send packets. There are a certain set of global variables associated with the networking code, and in order to make the networking codes support partitioning, the set of global variables associated with networking are replicated, one copy  47  for each v-net domain, such that the operating system effectively contains, rather than one copy of the networking data structures, N instantionations of the networking stack, replicating all the various functions of the networking code, including replicated routing tables and replicated TCP control blocks linked together throughout the basic data structure. Thus, effectively all of the important variables in the networking system are replicated, so that they can be independently managed. This can be thought of as an operating system with N instantiations of the networking system.  
         [0020]    The basic approach of the v-net code is to take global variables that need to be replicated for each v-net domain, and to make an array of them. As an example tcpstat, the tcp statistics structure, is declared in tcp_var.h struct tcpstat { . . . } and defined in tcp_input. c as struct tcpstat tcpstat. To have a separate set of statistics for each v-net domain requires changing the definition to struct tcpstat tcpstat[NVNET] and changing all references to index by the appropriate v-net domain number.  
         [0021]    To make v-net facility a configuration option, the declarations and references are encapsulated in macros. The macros generate arrays when v-nets are configured in and scalars when v-nets are deconfigured. As an example the tcpstat declaration becomes VDECL (struct tcpstat, tcpstaT), in which the first macro argument is the type, and the second macro argument is the name. It will be noted that the variable name is changed from tcpstat to tcpstaT. This convention is followed throughout the global variable generation, i.e., variables that are virtualized and global across more than one file are changed to have the final letter in their name capitalized. This is done for three reasons:  
         [0022]    1) to differentiate global variables from local variables and/or types of the same name for readability,  
         [0023]    2) to ensure that all references to global variables are fixed appropriately (by causing a compile error if the variable name is not changed); and  
         [0024]    3) to denote global variables plainly for possible future changes.  
         [0025]    References to virtualized variables are made using one of two macros,_v(name), or _V(name, index), where name is the variable name and index is the v-net domain index to be used. The macro _v uses a per CPU global index variable vnetindex. It will be noted that all references to virtualized variables must be made with these macros, without exception, so that the references are correct without requiring #ifdef&#39;s when v-nets are configured or deconfigured.  
         [0026]    In addition to defining a methodology that handles virtualization of variables, a selection is needed of the correct set of global variables to be replicated for each v-net domain, and the replicated variables need to be correctly referenced by macros in the appropriate v-net domain. For example, global variables can be identified by using a script that analyzes object (_o) files for the global variables they define, by code inspection, or by information from other sources (see for example the tables of global variables in TCP/IP Illustrated, Volume 2: The Implementation, Gary R. Wright and W. Richard Stevens, Addison-Wesley 1995, p. 64, 97, 128, 158, 186, 207, 248, 277, 305, 340, 383, 398, 437, 476, 572, 680, 715, 756, 797, 1028, and 1051).  
         [0027]    The following Appendix A is basically a table of the global variables that are virtualized in some implementations, listing the name and the purpose of the variable. The variables that are virtualized are generally marked “virtualized” in the table. Although virtualized variables shown in the table are usually marked “virtualized,” other variables in the table have been analyzed but excluded from virtualization. All of the “virtualized” variables are essentially replicated, such that each v-net maintains its own set of these variables. Then macros, program conventions that allow textural substitution, are provided, such that everywhere a global variable is accessed, a replacement access is a macro reference selected from the correct set of variables based on the correct v-net.  
         [0028]    In the present embodiment, multiple networking domains are implemented by the same operating system, unlike previous approaches, in which for example a computer is subdivided into virtual domains that partition the hardware and run separate operating systems in each domain.  
       appendix A. Variable Analysis  
       [0029]    [0029]                                                     NOTE: In the Analysis/Disposition column, “Virtualized” means the       variable becomes an array when vnets are configured (see the description       above); “Invariant” means a separate instance of the variable is       not needed for different vnet domains; and “Not Virtualized” means       there was a choice about virtualization (e.g., whether a Tunable could have       a different value in different domains), but the choice was made not to       virtualize the variable.                    Defining       Analysis/       Variable   Data Type   File   Description   Disposition               Head   static struct   igmp.c   Head of router_info linked list.   Virtualized.           router_info*       Addmask_key   static char*   radix.c   Temporary storage for   Invariant.                   m_addmask.       arp_allocated   static int   if_ether.c   Total number of llinfo_arp   Virtualized.                   structures allocated.       arp_inuse   static int   if_ether.c   Current number of llinfo_arp   Virtualized.                   structures in use.       arp_maxtries   static int   if_ether.c   Tunable. Maximum number of   Tunable. Not                   retries for an arp request.   virtualized.       arp_proxyall   static int   if_ether.c   Tunable. Enables forming a   Tunable. Not                   proxy for all arp requests.   virtualized.       arpinit_done   static int   if_ether.c   Indicates initialization is done.   Invariant.                       Initialization                       handles all                       vnets.       arpintrq   struct ifqueue   if_ether.c   Arp interrupt request queue.   Invariant.                   Shared by all vnets. Vnet                   switching when pulled off                   queue.       arpt_down   static int   it_ether.c   Tunable. No. of seconds   Tunable. Not                   between ARP flooding   virtualized.                   algorithm.       arpt_keep   static int   it_ether.c   Tunable. No. seconds ARP   Tunable. Not                   entry valid once resolved.   virtualized.       arpt_prune   static int   it_ether.c   Tunable. No. seconds between   Tunable. Not                   checking ARP list.   virtualized.       bpf_bufsize   static int   bpf.c   Tunable.   Tunable. Not                       virtualized.       bpf_cdevsw   static struct   bpf.c   Table of entry point function   Invariant.           cdevsw       pointers.       bpf_devsw_installed   static int   bpf.c   Initialization flag.   Invariant.       bpf_dtab   static struct   bpf.c   Descriptor structure, one per   Invariant.           bpf_d       open bpf device.           (NBPFILTER)       bpf_dtab_init   static int   bpf.c   Another initialization flag.   Invariant.       bpf_iflist   static struct   bpf.c   Descriptor associated with each   Invariant.           bpf_if       attached hardware interface.       clns_recvspace   static u_long   raw_clns.c   Constant (patchable). Amount   Not virtualized.                   of receive space to reserve in                   socket.       clns_sendspace   static u_long   raw_clns.c   Constant (patchable). Amount   Not virtualized.                   of send space to reserve in                   socket.       clns_usrreqs   struct pr_usrreqs   raw_clns.c   Function pointers for clns user   Invariant.                   requests.       clnsg   struct clnsglob   raw_clns.c   Global state associated with   Virtualized.                   ray_clns.c, including list heads                   and counters.       clnsintrq   struct ifqueue   raw_clns.c   Clns interrupt request queue.   Invariant.                   Shared by all vnets. Vnet                   switching done when removed                   from queue.       clnssw   struct protosw   raw_clns.c   Pointers to protocol entry   Invariant.                   points &amp; associated data.       counter   static u_int64_t   ip_fw.c   Counter for ipfw_report.   Virtualized.       div_recvspace   static u_long   ip_divert.c   Amount of receive space to   Invariant.                   reserve in socket.       div_sendspace   static u_long   ip_divert.c   Amount of send space to   Invariant.                   reserve in socket       divcb   static struct   ip_divert.c   Head of inpcb structures for   Virtualized.           inpcbhead       divert processing.       divcbinfo   static struct   ip_divert, c   Pcbinfo structure for divert   Virtualized.           inpcbinfo       processing       dst   static struct   bpf.c   Sockaddr prototype.   Invariant.           sockaddr       err_prefix   char[]   ip_fw.c   Constant string for printfs.   Invariant.       etherbroadcastaddr   u_char [6]   if_ethersubr.c   Constant. Ethernet broadcast   Invariant.                   link address.       expire_upcalls_ch   static struct   ip_mroute.c   Callout handle for   Virtualized.           callout_handle       expire_upcalls.       fcstab   static u_short   ppp_tty.c   Constant. Table for FCS   Invariant.           [256]       lookup.       frag_divert_port   static u_short   ip_input.c   Divert protocol port.   ?                   Conditionally compiled iwith                   IPDIVERT.       fw_debug   static int   ip_fw.c   Tunable. Enables debug print.   Not virtualized.       fw_one_pass   static int   ip_fw.c   Tunable. Enables accepting   Not virtualized.                   packet if passes first test.       fw_verbose   static int   ip_fw.c   Tunable; controls verbosity of   Not virtualized.                   firewall debugging messages.       fw_verbose_limit   static int   ip_fw.c   Tunable. Limits amount of   Not virtualized.                   logging.       have_encap_tunnel   static int   ip_mroute.c   Indicates presence of an   Virtualized.                   encapsulation tunnel.       icmpbmcastecho   static int   ip_icmp.c   Tunable flag. Disables   Not virtualized.                   broadcasting of ICMP echo and                   timestamp packets.       icmpdst   static struct   ip_icmp.c   Saves the source address for   Virtualized.           sockaddr_in       ifaof_ifpforaddr.       icmpgw   static struct   ip_icmp.c   Holds the ip source address in   Virtualized.           sockaddr_in       icmp_input.   May not be                       necessary       icmplim   static int   ip_icmp.c   Tunable. ICMP error-response   Not virtualized.                   band with limiting sysctl.       icmpmaskrepl   static int   ip_icmp.c   Tunable flag. Enables ICMP   Not virtualized.                   mask replacement.       icmpprintfs   int   ip_icmp.c   Enables printfs in icmp code.   Not virtualized.       icmpsrc   static struct   ip_icmp.c   Holds the ip dest address in   Virtualized.           sockaddr_in       icmp_input.   May not be                       necessary       icmpstat   static struct   ip_icmp.c   Icmp statistics.   Virtualized.           icmpstat       if_indeX   int   if.c   Number of configured   Virtualized.                   interfaces.       if_indexliM   static int   if.c   Number of entries in   Virtualized.                   ifnet_addrS array.       ifneT   struct ifnethead   if.c   Head of list of ifnet structures.   Virtualized.       ifnet_addrS   struct iffaddr**   if.c   Array of pointers to link level   Virtualized.                   interface addresses.       ifqmaxlen   int   if.c   Constant. Maximum queue   Invariant.                   length for interface queue.       igmp_all_hosts_group   static u_long   igmp.c   Host order of   Invariant.                   INADDR_ALLHOSTS_GROUP                   constant       igmp_all_rtrs_group   static u_long   igmp.c   Host order of   Invariant.                   INADDR_ALLRTS_GROUP                   constant.       igmp_timers_are_running   static int   igmp.c   Flag indicating any igmp timer   Virtualized.                   is active.       igmprt   static struct route   igmp.c   Temporary variable.   Invariant.       igmpstat   static struct   igmp.c   Igmp statistics.   Virtualized.           igmpstat       in_ifaddrheaD   struct   ip_input.c   Head of in_ifaddr structure list.   Virtualized.           in_ifaddrhead       in_interfaces   static int   in.c   Incremented each time a non-   Invariant.                   loopback interface is added to   Never read.                   in_ifaddrheaD. Not read.   Dead code.       in_multiheaD   struct   in.c   Head of list of   Virtualized.           in_multihead       in_multistructures (multicast                   address).       inetclerrmap   u_char []   ip_input.c   Array of constants (error   Invariant.                   numbers).       inetdomain   struct domain   in_proto.c   Pointers to switch table,   Invariant.                   initialization, etc. for internet                   domain.       inetsw   struct protosw   in_proto.c   Pointers to entry points for   Invariant.                   various internet protocols.       inited   static int   if.c   Flag indicating initialization   Invariant.                   has been performed.                   Initialization does all vnets.       ip_acceptsourceroute   static int   ip_input.c   Tunable flag. Enables   Tunable. Not                   acceptance of source routed   virtualized.                   packets.       ip_defttl   int   ip_input.c   Tunable. Default time to live   Tunable. Not                   from RFC 1340.   virtualized.       ip_divert_cookiE   u_intl6_t   ip_divert.c   Cookie passed to user process.   Virtualized.       ip_divert_porT   u_short   ip_divert.c   Global “argument” to   Virtualized.                   div_input. Used to avoid                   changing prototype.       ip_dosourceroute   static int   ip_input.c   Tunable flag. Enables acting as   Tunable. Not                   a router.   virtualized.       ip_fw_chaiN   struct ip_fw_head   ip_fw.c   Head of ip firewall chains.   Virtualized.       ip_fw_chk_ptr   ip_fw_chk_t*   ip_input.c   IP firewall function callout   Invariant.                   pointer; value depends on                   loading fw module.       ip_fw_ctl_ptr   ip_fw_ctl_t*   ip_input.c   IP firewall function callout   Invariant.                   pointer; value depends on                   loading fw module.       ip_fw_default_rulE   struct   ip_fw.c   Pointer to default rule for   Virtualized.           ip_fw_chain*       firewall processing.       ip_fw_fwd_addR   struct   ip_input.c   IP firewall address.   Virtualized.           sockaddr_in*       ip_ID   u_short   ip_output.c   IP packet identifier   Virtualized.                   (increments).       ip_mcast_src   ulong (*)(int)   ip_mroute.c   Pointer to function; selection   Invariant.                   depends on compile options.       ip_mforward   int(*)(struct ip*,   ip_mroute.c   Function pointer set by module   Invariant.           struct ifnet*, . . . )       installation.       ip_mrouteR   struct socket*   ip_mroute.c   Socket of multicast router   Virtualized.                   program.       ip_mrouter_done   int (*)(void)   ip_mroute.c   Function pointer set by module   Invariant.                   installation.       ip_mrouter_get   int (*)(struct   ip_mroute.c   Function pointer selected by   Invariant.           socket*, struct       compile options.           sockopt*)       ip_mrouter_set   int (*)(struct   ip_mroute.c   Function pointer selected by   Invariant.           socket*, struct       compile options.           sockopt*)       ip_nat_clt_ptr   ip_nat_ctl_t*   ip_input.c   IP firewall function callout   Invariant.                   hook; set by module install.       ip_nat_ptr   ip_nat_t*   ip_input.c   IP firewall function callout   Invariant.                   hook; set by module install.       ip_nhops   static int   ip_input.c   Hop count for previous source   Virtualized.                   route.       ip_protox   u_char   ip_input.c   Maps protocol numbers to   Invariant.           [PROTO_MAX]       inetsw array.       ip_rsvpD   struct socket*   ip_input.c   Pointer to socket used by rsvp   Virtualized.                   daemon.       ip_rsvp_on   static int   ip_input.c   Boolean indicating rsvp is   Virtualized.                   active.       ip_srcrt   struct ip_srcrt   ip_input.c   Previous source route.   Virtualized.       ipaddR   struct   ip_input.c   Holds ip destination address for   Virtualized.           sockaddr_in       option processing.       ipflowS   static struct   ip_flow.c   Hash table head for ipflow   Virtualized.           ipflowhead       structs       ipflow_active   static int   ip_flow.c   Tunable. Enables “fast   Invariant.                   forwarding” flow code.       ipflow_inuse   static int   ip_flow.c   Count of active flow structures.   Virtualized.       ipforward_rt   static struct route   ip_input.c   Cached route for ip forwarding.   Virtualized.       iforwarding   int   ip_input.c   Tunable that enabales ip   Virtualized.                   forwarding.       ipintrq   struct ifqueue   ip_input.c   Ip interrupt request queue for   Invariant.                   incoming packets. Vnet set                   when packets dequeued.       ipport_firstauto   static int   ip_pcb.c   Bounds on ephemeral ports.   Invariant.       ipport_hifirstauto   static int   ip_pcb.c   Bounds on ephemeral ports.   Invariant.       ipport_hilastauto   static int   ip_pcb.c   Bounds on ephemeral ports.   Invariant.       ipport_lastauto   static int   ip_pcb.c   Bounds on ephemeral ports.   Invariant.       ipport_lowfirstauto   static int   ip_pcb.c   Bounds on ephemeral ports.   Invariant.       ipport_lowlastauto   static int   ip_pcb.c   Bounds on ephemeral ports.   Invariant.       ipprintfs   static int   ip_nput.c   Flag for debug print.   Invariant.       ipq   static struct ipq   ip_input.c   Head of ip reassembly hash   Virtualized.           [IPREASS_NHASH]       lists.       ipqmaxlen   static int   ip_input.c   Patchable constant that sets   Invariant.                   maximum queue length for                   ipintrq.       isendredirects   static int   ip_input.c   Tunable that enable sending   Invariant.                   redirect messages.       istaT   struct ipstat   ip_input.c   Ip statistics counters.   Virtualized.       k_igmpsrc   static struct   ip_mroute.c   Prototype sockaddr_in.   Invariant.           sockaddr_in       last_adjusted_timeout   static int   ip_rmx.c   Time value of last adjusted   Virtualized.                   timeout.       last_encap_src   static u_long   ip_mroute.c   Cache of last encapsulated   Virtualized.                   source address?       last_encap_vif   struct vif*   ip_mroute.c   Last encapsulated volume tag   Virtualized.                   (vif).       last_zeroed   static int   radix.c   Number of bytes zeroed last   Invariant.                   time in addmask_key.       legal_vif_num   int (*)(int)   ip_mroute.c   Pointer to function selected by   Invariant.                   module installation.       llinfo_arP   struct   if_ether.c   Head of llinfo_arp linked list.   Virtualized.           llinfo_arp_head       log_in_vain   static int   tcp_input.c   Tunables that enable logging of   Invariant.               udp_usrreq.c   “in vain” connections.       loif   struct ifnet   if_loop.c   Array of ifnet structs fro   Invariant.           [NLOOP]       loopback device. One per                   device, therefore invariant.       mask_mhead   struct   radix.c   Head of mask tree.   Invariant.           radix_node_head*       max_keylen   static int   radix.c   Maximum key length of any   Invariant.                   domain.       maxnipq   static int   ip_input.c   Constant (nmbcluslter/4) that is   Invariant?                   maximum number of ip   Scaled?                   fragments waiting assembly.                   Note: should this be scaled by                   VNET?       mfctable   static struct mfc*   ip_mroute.c   Head of mfc hash table.   Virtualized.           [MFCTBLSIZ]       mrt_ioctl   int (*)(int,   ip_mroute.c   Function pointer selected by   Invariant.           caddr_t struct       module initialization.           proc*)       mrtdebug   static u_int   ip_mroute.c   Enables debug log messages.   Invariant.       mrtstat   static struct   ip_mroute.c   Multicast routing statistics.   Virtualized.           mrtstat       mtutab   static int []   ip_icmp.c   Static table of constants.   Invariant.       multicast_decap_if   static struct ifnet   ip_mroute.c   Fake encapsulator interfaces.   Virtualized.           [MAXVIFS]       multicast_encap_iphdr   static struct ip   ip_mroute.c   Multicast encapsulation header.   Invariant.               nexpire   static u_char   ip_mroute.c   Count of number of expired   Virtualized.           [MFCTBLSIZ]       entries in hash table?       nipq   static int   ip_input.c   Number of ipfragment chains   Virtualized.                   awaiting reassembly.       normal_chars   static char []   radix.c   Static table of mask constants.   Invariant.       nousrreqs   static struct   in_proto.c   Static structure of null function   Invariant.           pr_usrreqs   ipx_proto.c   pointers.       null_sdl.96   static struct   if_ether.c   Static null sockaddr_dl   Invariant.           sockaddr_dl       structure.       numvifs   static vifi_t   ip_mroute.c   Number of virtual interface   Virtualized.                   structures.       old_chk_ptr   static   ip_fw.c   Function pointer holding   Invariant.           ip_fw_chk_t       previous state when module                   loads.       old_ctl_ptr   static ip_fw_ctl_t   ip_fw.c   Function pointer holding   Invariant.                   previous state when module                   loads.       paritytab   static unsigned   ppp_tty.c   Static array of parity constants.   Invariant.           [8]       pim_assert   static int   ip_mroute.c   Enables pim assert processing.   Virtualized.       ppp_compressors   static struct   if_ppp.c   Static list of known ppp   Invariant.           compressor [8]       compressors.       ppp_softc   struct ppp_softc   if_ppp.c   Array of softc structures for   Invariant.       pppdisc   [NPPP]       ppp driver; one per device.       raw_recvspace   static u_long   raw_cb.c   Patchable constant that is   Invariant.                   amount of receive space to                   reserve in socket.       raw_sendspace   static u_long   raw_cb.c   Patchable constant that is   Invariant.                   amount of send space to reserve                   in socket.       raw_usrreqs   struct protosw   raw_usrreq.c   Table of function pointers.   Invariant.       rawcb_lisT   struct   raw_cb.c   Head of rawcb (raw prototocol   Virtualized.           rawcb_list_head       control blocks) list.       rawclnsdomain   struct domain   raw_clns.c   Table of function pointers.   Invariant.       rip_recvspace   static u_long   raw_ip.c   Tunable, amount of receive   Tunable. Not                   space to reserve in socket.   virtualized.       rip_sendspace   static u_long   raw_ip.c   Tunable, amount of send space   Tunable. Not                   to reserve in socket.   virtualized.       rip_usrreqs   struct pr_usrreqs   raw_ip.c   Table of function pointers.   Invariant.       ripcb   static struct   raw_ip.c   Head of raw ipcontrol blocks   Virtualized.           inpcbhead       ripcbinfo   struct inpcbinfo   raw_ip.c   Pcb info. structure for raw ip.   Virtualized.       ripsrc   static struct   raw_ip.c   Static temporary variable in   Invariant.           sockaddr_in       rip_input       m_mkfreelist   static struct   radix.c   Cache of free radix_mask   Invariant.           radix_mask*       structures.       m_ones   static char*   radix.c   One mask computed from   Invariant.                   maximum key length.       m_zeros   static char*   radix.c   Zeros mask computed from   Invariant.                   maximum key length.       ro   static struct route   ip_mroute.c   Temporary variable to hold   Invariant.           ro       route.       route_cB   struct route_cb   route.c   Counts on the number of   Virtualized.                   routing socket listeners per                   protocol.       route_dst   static struct   rtsock.c   Null address structure for   Invariant.           sockaddr route       destination.       route_proto   static struct   rtsock.c   Static prototype of structure   Invariant.           sockproto       used to pass routing info.       route_src   static struct   rtsock.c   Null address structure for   Invariant.           sockaddr       source.       route_usrreqs   static struct   rtsock.c   Table of function pointers for   Invariant.           pr_usrreqs       entry points.       routedomain   struct domain   rtsock.c   Table of function pointers for   Invariant.                   entry points.       route_alert   static struct mbuf*   igmp.c   Statically constructed router   Invariant.                   alert option.       routesw   struct protosw   rtsock.c   Table of function pointers for   Invariant.                   entry points.       rsvp_oN   int   ip_input.c   Count of number of open rsvp   Virtualized.                   control sockets.       rsvp_src   static struct   ip_mroute.c   Sockaddr prototype.   Invariant.           sockaddr_in       rsvpdebug   static u_int   ip_mroute.c   Enables debug print.   Invariant.       rt_tableS   struct   route.c   Head of the routing tables (a   Virtualized.           radix_node_head*       table per address family.)           [AF_AX + 1]       rtq_minreallyold   static int   in_rmx.c   Tunable; minimum time for old   Invariant.                   routes to expire.       rtq_reallyold   statinc int   in_rmx.c   Amount of time before old   Virtualized.                   routes expire.       rtq_timeout   static int   in_rmx.c   Patchable constant timeout   Invariant.                   value for walking the routing                   tree.       rtq_toomany   static int   in_rmx.c   Tunable that represents the   Invariant.                   number of active routes in the                   tree.       rtstaT   struct rtstat   route.c   Routing statistics structure.   Virtualized.       rttrash   static int   route.c   Number of rtentrys not linked   Dead code. Not                   to the routing table. Never read,   virtualized.                   dead code.       sa_zero   struct sockaddr   rtsock.c   Zero address return in error   Invariant.                   conditions.       sin   static struct   if_ether.c   Sockaddr prototype passed to   Invariant.           sockaddr_inarp   if_mroute.c   rtallocl.       sl_softc   static struct   if_sl.c   Softc structure for slip driver;   Invariant.           sl_soft [NSL]       one per device.       slipdisc   static struct   if_sl.c   Table of function pointers to   Invariant.           linesw       slip entry points.       srctun   static int   ip_mroute.c   Counter throttling error   Invariant.                   message to log.       subnetsarelocal   static int   in.c   Tunable flag indicating subnets   Virtualized.                   are local.       tbfdebug   static u_int   ip_mroute.c   Tbf debug level.   Invariant.       tbftable   static struct tbf   ip_mroute.c   Token bucket filter structures.   Virtualized.           [MAXVIFS]       tcB   struct inpcbhead   tcp_input.c   Head structure for tcp pcb   Virtualized.                   structures.       tcbinfO   struct inpcbinfo   tcp_input.c   PCB info structure for tcp.   Virtualized.       tcp_backoff   int []   tcp_timer.c   Table of times for tcp backff   Invariant.       tcp_ccgeN   tcp_cc   tcp_input.c   Connection count (per rfc   Virtualized.           (u_int32_t)       1644).       tcp_delack_enabled   int   tcp_input.c   Tunable that enables delayed   Tunable. Not                   acknowledgments.   virtualized.       tcp_do_rfc1323   static int   tcp_subr.c   Tunable enables rcf 1323   Tunable. Not                   (window scaling and   virtualized.                   timestamps.)       tcp_do_rfc1644   static int   tcp_subr.c   Tunable enables rfc 1644.   Tunable. Not                       virtualized.       tcp_keepcnt   static int   tcp_timer.c   Patchable constant for   Invariant.                   maximum number of probes                   before a drop.       tcp_keepidle   int   tcp_timer.c   Tunable value for keep alive   Tunable. Not                   idle timer.   virtualized.       tcp_keepinit   int   tcp_timer.c   Tunable value for initial   Tunable. Not                   connect keep alive.   virtualized.       tcp_maxidle   int   tcp_timer.c   Product of tcp_keepcnt*   Invariant.                   tcp_keepintvl; recomputed in                   show timeout.       tcp_maxpersistidle   static int   tcp_timer.c   Patchable constant that is   Invariant.                   default time before probing.       tcp_mssdflt   int   tcp_subr.c   Tunable default maximum   Tunable. Not                   segment size.   virtualized.       tcp_noW   u_long   tcp_input.c   500 msec. counter for RFC1323   Virtualized.                   timestamps.       tcp_outflags   u_char   tcp_fsm.h   Static table of flags in   Invariant.           [TCP_NSTATES]       tcp_output.       tcp_rttdflt   static int   tcp_subr.c   Tunable. Dead code, value not   Invariant. Dead                   accessed   code       tcp_sendspace   u_long   tcp_usrreq   Tunable value for amount of   Tunable. Not                   send space to reserve on socket.   virtualized.       tcp_totbackoff   static int   tcp_timer.c   Sum of tcp_backoff.   Invariant.       tcp_usrreqs   struct pr_usrreqs   tcp_usrreq.c   Table of function pointers for   Invariant.                   tcp user request functions.       tcprexmtthresh   static int   tcp_input.c   Patchable constant; number of   Invariant.                   duplicate acks to trigger fast                   retransmit.       tcpstaT   struct tcpstat   tcp_input.c   TCP statistics structure.   Virtualized.       tun_cdevsw   struct cdevsw   if_tun.c   Table of function pointers for   Invariant.                   tunnel interface entry points.       tun_devsw_installed   static int   if_tun.c   Flag indiating tun devsw table   Invariant.                   installed.       tunctl   static struct   if_tun.c   Softc structure for tunnel   Invariant.           tun_softc       interface; one per device.           [NTUN]       tundebug   static int   if_tun.c   Flag enables debut print.   Invariant.       udb   static struct   udp_usrreq.c   UDP inpcb head structure.   Virtualized.           impcbhead       udbinfo   static struct   udp_usrreq.c   UDP inpcb info. structure.   Virtualized.           impcbinfo       udp_in   static struct   udp_usrreq.c   Prototype sockaddr for   Invariant.           sockaddr_in       AF_INET.       udp_recvspace   static u_long   udp_usrreq.c   Tunable; amount of receive   Tunable. Not                   space to reserve on socket.   virtualized.       udp_sendspace   static u_long   udp_usrreq.c   Tunable; amount of send space   Tunable. Not                   to reserve on socket.   virtualized.       udp_usrreqs   struct pr_usrreqs   udp_usrreq.c   Table of function pointers for   Invariant.                   entry points.       udpcksum   static int   udp_usrreq.c   Tunable; enables udp   Tunable. Not                   checksumming.   virtualized.       udpstat   struct udpstat   udp_usrreq.c   Udp statistics structure.   Virtualized.       useloopback   static int   it_ether.c   Tunable; enables use of   Tunable. Not                   loopback device for localhost.   virtualized.       version   static int   ip_mroute.c   Version number of MRT   Invariant.                   protocol.       viftable   static struct vif   ip_mroute.c   Table of vifs (virtual interface   Virtualized.           [MAXVIFS]       structure).       zeroin_addr   struct in_addr   in_pcb.c   Zero&#39;d internet address.   Invariant.                    
         [0030]    Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.