Re: [nsp] Half-duplex 10BASE-T interfaces of a Cisco 4x00

From: Quan Nguyen (quan@vortex.cc.mcgill.ca)
Date: Fri Feb 04 2000 - 22:54:53 EST


On Fri, 4 Feb 2000, Rubens Kuhl Jr. wrote:

> Does someone know a trick in order to make use of the 2 half-duplex Ethernet
> interfaces of a Cisco 4000 (or any other 4x00) in the same subnet ? A single
> half-duplex interface can barely forward and receive 4 Mbps of full-duplex
> traffic, and I'm trying to figure out a way to activate the other
> half-duplex interface on the same subnet to share the load. Input by one
> interface and output by the other is one ideia, but any load-sharing
> mechanism is wellcome.

There is a feature called 'Simplex Ethernet Interfaces". An example
can be found at: http://www.cisco.com/univercd/cc/td/doc/product/software/
ios120/12cgcr/np1_c/1cprt2/1cip.htm#18783

However, that technique is a bit a pain to maintain since it requires
static ARP entries. In my environment, I use OSPF and play with
"inverse" costs on each link.

+----------+ cost 20 cost 10 +----------+
| |<-----------------------| |
| Router A | OSPF | Router B |
| |----------------------->| |
+----------+ cost 10 cost 20 +----------+

The arrow denotes the direction of the traffic, each link is on a
different subnet. There is only an insignificant amount of
bidirectional traffic on each link used by OSPF.

Quan,

-------------Quan Nguyen-------------McGill UNIVERSITY---------------
   -o Voice (514)398-3709 Computing Center (Burnside Hall)
    ()/// FAX (514)398-6876 805 Sherbrooke St West, Rm 222
             quan@CC.McGill.CA Montreal, Quebec H3A 2K6



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