Re: ISN


braden@venera.isi.edu
Wed, 16 Mar 88 08:43:35 PST


        There is a bridge that is about 70% of a router. It is called
        REB (Remote Ethernet Bridge). The designer has taken a small
        number of the fields in the IP header and has done a similar
        implementation at level II.

        For example, REB can close loops. I can assign a weight to each
        line (i.e. one line is 9.6kb, another is T1, another is X.25,
        and another should hardly ever be used) and based on the weight
        and the network load, the REB will determine the routing the
        packet should take. In addition, it has implemented a TTL type
        of field so that packets that loop around between REBs get
        removed. You can configure in each REB what the maximum TTL
        should be and each outgoing packet gets assigned that number.
        As the packet passes thru other REBs, the number is decremented.
        When it hits zero, the packet is thrown away.

        There are many other functions that was designed via 802.3 D -
        Managament specs.

        What it cannot do is ARP or ICMP but if you are looking for a
        bridge replacement, you should seriously evaluate the RAD REB.

        Hank

I would describe this as a level-2 router, essentially an IMP for Ethernets.
Seems like a reasonable concept. The bridge guys work very hard to
keep the overhead low enough to handle back-to-back Ethernet packets;
can the REB guys do as well, with the extra protocol processing?

Bob Braden



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