Acknowledgments


The author would like the thank the participants in the Internet tcp-group for their assistance in preparing this, and to the various radio amateurs who have tested RSPF 2.1 on the air, for their assistance. Special thanks to Anders Klemets SM0RGV for drafting the first implementation of RSPF2.1, and to Mike Bilow N1BEE for creating a stable implementation as well as for his assitance in editing this revision.

Appendix A. Router parameters


Every router must set a number of parameters in order to properly operate. While RSPF builds its routing matrix automatically, overall network efficiency and stability may require some fine-tuning based upon experience. These include parameters set for each data link or subnetwork layer entity (i.e., each radio channel) and for the router in general. Commands given below are not necessarily the statements used in real implementations.

Link/subnet settings:

Set Link cost

This is the cost parameter based upon the link speed and type. Since the overall cost of the end-to-end path is minimized by the RSPF spanning tree, link cost should be set to arrive at the best overall network performance. The legal range is 1-127. This is sent in routing update bulletins.

Node settings:

Add/Delete Node group: [IPaddr]/bits {cost}.

This allows a node to announce its ability to serve a group of nodes, identified using the standard NOS convention of address/significant bits. Thus a node group setting of [44.56.4.1]/25 will match all nodes from [44.56.4.1] to [44.56.4.127]. Cost is optional; if set, this cost to will be propogated to reach such nodes; otherwise, the link's default is used. This is fed into the manual route table. A given router may support multiple node groups; this facilitatates operation near the boundary of address-subnet regions. Such a router may use a lower node group cost for its own node group than for adjacent (or nearby) ones, so that it is not a favored route to other groups. High costs for other node groups are still useful because they define whether an adjacency is governed by horizon local or horizon portable. (Use of a Private flag for this function, instead of propagating a higher cost, is for further study.)

Set horizon link:

This sets the horizon value for the node's routing bulletins apropos 32-bit addresses of other adjacent routers. This should be high enough to propogate across the backbone, if a backbone router.

Set horizon group:

This sets the horizon value for the node's routing bulletins apropos node group addresses (fewer than 32 bits matched) nominally served (providing end user adjacencies) by this router. Usually matches the horizon link value.

Set horizon local:

This sets the horizon vaue for the node's routing bulletins apropos full link addresses (32 bits) to non-routers within the router's node group area. This is set to a low value so that only other routers serving the same or overlapping node group(s) will receive these messages.

Set horizon portable:

This sets the horizon value for the node's routing bulletins apropos full link addresses (32 bits) to non-router adjacencies not within a supported node group. This allows portable end nodes to have their location in the network propogated farther than the local horizon; this is usually set the same as horizon group.

Set RRH timer:

This sets the time, in seconds, between router-router hello (RRH) broadcasts. Initial suggestion: 900.

Set RSPF timer:

This sets the time, in seconds, between newly originated link state bulletins. Initial suggestion: 900.

Set suspect timer:

This sets the time, in seconds, after which a connectionless adjacency is "suspect" if no packets are received from it. The route is then tested (e.g., pinged). Initial suggestion: 2000.

Set suspect count (maxping):

This sets the number of times an ICMP echo (ping) should be sent after a node is suspect, before it is removed from the adjacency list. Initial suggestion: 3.

APPENDIX B. Schematic representation of RSPF tables.

             ---------------------------------------------------+
            / ADJAC.        LINKS                     PATHS     |
(SNAcP)
    SUBNETS-->+----+       +------+   [SPF]          +-----+    |        
              |II. |------>|V.1.1 |              --->|V.1.2|    |
    RRH IN--->|    |       |      |    TRIAL    /    |     |    |
              +----+       |      |-->+-----+  /     +-----+    |
       BULLETINS<--------->+------+   |V.1.3|-/least    |       |     
        |                   ^         |     |  cost     V       |
      +------+        non-  |         +-----+       +-------+   |
      |IV.2.4|      private |                       |V.1.2.1|  /
      |      |  +-------+--/                        |       |<-
      +------+  | V.4   |-------------------------->|       |
      ROUTERS   |       |    all manual routes      +-------+
                +-------+                             ROUTE
               MANUAL ROUTE 

Last Modified: Wed, 22 Nov 2000
Copyright © 2000 Craig Small
csmall@small.dropbear.id.au