Date: Mon, 4 Mar 2002 00:26:55 -0600 From: Vikram Kulkarni <vkulkarn@brownforces.org> To: questions@freebsd.org Subject: Re: multiple defaultrouter Message-ID: <20020304002654.D2219@padu.brownforces.org> In-Reply-To: <20020304171534.H576@k7.mavetju.org>; from edwin@mavetju.org on Mon, Mar 04, 2002 at 05:15:34PM %2B1100 References: <20020304001952.PLTC8848.mta02-svc.ntlworld.com@there> <005301c1c32f$21a623a0$1e01a8c0@lc.ca.gov> <20020303214112.2e786336.chip@wiegand.org> <20020304171534.H576@k7.mavetju.org>
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On Mon, Mar 04, 2002 at 05:15:34PM +1100, Edwin Groothuis wrote:
>
> But what does it do then? Does it send every other packet to the
> other gateway or is it saving the second one in case the first one
> dies?
They're prioritized I believe... if it cant reach the first one, then it
tries the second one...
Its also required by RFC 1122:
Network Working Group Internet Engineering Task Force
Request for Comments: 1122 R. Braden, Editor
October 1989
Requirements for Internet Hosts -- Communication Layers
Status of This Memo
This RFC is an official specification for the Internet community. It
incorporates by reference, amends, corrects, and supplements the
primary protocol standards documents relating to hosts. Distribution
of this document is unlimited.
Summary
This is one RFC of a pair that defines and discusses the requirements
for Internet host software. This RFC covers the communications
protocol layers: link layer, IP layer, and transport layer; its
companion RFC-1123 covers the application and support protocols.
....
(Quote from the bottom of page 48 and top of page 49 of RFC1122, section
3.3.1.2)
When there is no route cache entry for the destination host
address (and the destination is not on the connected
network), the IP layer MUST pick a gateway from its list of
"default" gateways. The IP layer MUST support multiple
default gateways.
...
(or from the table on page 74 (column headers from page 72) of the same
RFC)
| | | | |S| |
| | | | |H| |F
| | | | |O|M|o
| | |S| |U|U|o
| | |H| |L|S|t
| |M|O| |D|T|n
| |U|U|M| | |o
| |S|L|A|N|N|t
| |T|D|Y|O|O|t
FEATURE |SECTION | | | |T|T|e
-------------------------------------------------|--------|-|-|-|-|-|--
...
OUTING OUTBOUND DATAGRAMS: | | | | | | |
...
If no cache entry, use default gateway |3.3.1.2 |x| | | | |
Support multiple default gateways |3.3.1.2 |x| | | | |
-Vik
--
vikram kulkarni All states are abstractions.
vkulkarn@uiuc.edu -Octun Politicus
vkulkarn@brownforces.org Bene Gesserit Archives
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