Problemy s pristupem na internet

[Martin Mačok]

On Tue, Dec 19, 2000 at 03:39:48PM +0100, Adam Rogalewicz wrote:
>  Dan Barčot napsal:
> > Aktivni smerovani
> > 
> > sitova adresa      maska            adresa brany    rozhrani        metrika
> > ----------------------------------------------------------------------------
> > 0.0.0.0          0.0.0.0          10.0.0.1        10.0.0.1        1
> > 0.0.0.0            0.0.0.0          192.168.1.250   192.168.1.8     1
> 
> Proc mate 2 defaultni brany to je nesmysl.

[Nazdar Adame]

Je pravda, ze v tomto pripade to asi nesmysl bude, ale obecne to
nesmysl byt nemusi.

Pokud jsou nastaveny 2 default gateway, na nekterych systemech muzou
byt round-robin-ovany (napr. Solaris tusim round-robinuje na urovni
IP, jinak na TCP stream by to asi bylo vhodnejsi), jinde muze byt
druha default gateway pouzita v pripade vypadku prvni
(high-availability ... i kdyz na to by bylo robustnejsi pouzit OSPF
apod.). Cisca s tim take neco umi delat ...

Reference:
from tcpip illustrated, chap 9,
---- SNIP -- SNIP ----
The Host Requirements RFC specifically states that the IP layer must
support multiple default routes. Many implementations, however, don't
support this. When multiple default routes exist, a common technique
is to round robin among them. This is what Solaris 2.2 does, for
example.
---- SNIP -- SNIP ----

RFC1122, Page 49,
---- SNIP -- SNIP ----
, the IP layer MUST pick a gateway from its list of "default"
gateways.  The IP layer MUST support multiple default gateways.
---- SNIP -- SNIP ----

Nicmene je pravda, ze to neni vhodne reseni problemu a vyvolava to
zmatky (napr. na firewallech). Je to jeden z bodu RFC, ktery byva
ignorovan (napr. OpenBSD vice defaultnich gatewayi nepodporuje).

> Ujasnete si, co je to default gw a myslim, ze vam to dojde.

V tomto pripade bych se take priklonil k teto odpovedi ;-)

Preji hezky den

-- 
   Martin Mačok
  underground.cz
    openbsd.cz