Dynamic Routing, PPP and TCP/IP Question

Dynamic Routing, PPP and TCP/IP Question

Post by James.Brids » Tue, 25 May 1993 23:40:28

I have a network of Sparcs connected using Suns PPP product and running
the Sun routed. The network can be considered as being arranged thus:

               link 1              link 2
        /----------------\ /-------------------\
        |                | |                   |
     -----              -----               -----
     | A |              | B |               | C |
     -----              -----               -----
      |                                      |
                        link 3

Obviously under normal operation the routing tables route A-B over link1,
B-C over link2 and A-C over link3. In the event of a fault on any single
link then after 180s (routed uses RIP) the routing tables are updated
and a two hop alternative used (i.e. if link3 goes down the A-C has to go
via link1 and then link2).

This all works fine. However I have a few further requirements of which
I have ideas on and some of which I suspect might not be possible.
I would very much appreciate any comments/suggestions/criticism (VIA EMAIL
since we don't have news here :-( ) on the following points:

        1)      Can I speed the rerouting up? I don't see any way of
                changing the RIP packet timings on routed. In fact I
                guess the standard dictates these timings. I could
                get 'gated' and modify the source... The links are
                synchronous (64Kbps) and will ultimately be going
                over a 'virtually' error free optical fibre so we
                can virtually discount 'packet loss'. The application
                requires a bandwidth of about 20Kbps max.

        2)      When the routing tables are updated any current
                connections are obviously still using the old
                interface. The application needs to close the (TCP)
                connection and connect again. Is there any way
                to dynamically change existing connections? Would
                it be feasible to change the kernel structures on
                the fly to point at the new interface? Does anyone
                know of any code that does this?

        3)      Anybody used OSPF? Does it come close to any of the
                above? Is there a freely distributable Unix implementation

What I am trying to achieve is a software equivalent of having fast external
routers. I would welcome any comments or advice (by EMAIL please). I will
summarise to individuals or the net if demand warrants.


James Bridson                    STC Submarine Systems
Northern Telecom Europe Limited  Six Hills House, London Road,
                                 Stevenage, Hertfordshire SG1 1YB


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