Configuring Routing Table with Multiple Interfaces

Configuring Routing Table with Multiple Interfaces

Post by Scott B. Drummond » Tue, 06 Jun 2000 04:00:00



I'm trying to figure out how to set up my Sol 7 machine to use the installed
100-Mbit interface.  I have followed leads from previous posts and a
beginner's sysadmin guide that I have to the routing table.  However, the
documentation for how these things works is sparse and I'm afraid it will be
easy for me to do more harm than good.  That is where you good-Samaritan
types comes in.  ;)

My 10-Mbit Ethernet interface (hme0) is on a heavily loaded network and the
100-Mbit interface (hme1) is less-loaded and seems to have the same number
of hops to my most common destinations.  So, generally speaking, I'd like
all traffic to use hme1.

However, checking netstat -i tells me that hme1 is rarely used.  netstat -nr
tells me that hme1 is used for a very small subset of my destination
addresses.  Confusingly enough, the 'default' destination in the routing
table does not have an entry in the 'Interface' column.

So, specifically, how can I tell my machine to be more liberal with hme1?
Since I imagine this will mean specifying destination addresses that should
use that interface in the routing table, what criteria should I use in
choosing the destination addresses that use hme1?  Also, why is no interface
named in the 'default' destination row of my routing table?

Last, can anyone suggest a good book on this subject so I can educate myself
further?

Thanks,
Scott

 
 
 

Configuring Routing Table with Multiple Interfaces

Post by Andy » Tue, 06 Jun 2000 04:00:00




Quote:> I'm trying to figure out how to set up my Sol 7 machine to use the
installed
> 100-Mbit interface.  I have followed leads from previous posts and a
> beginner's sysadmin guide that I have to the routing table.  However,
the
> documentation for how these things works is sparse and I'm afraid it
will be
> easy for me to do more harm than good.  That is where you good-
Samaritan
> types comes in.  ;)

> My 10-Mbit Ethernet interface (hme0) is on a heavily loaded network
and the
> 100-Mbit interface (hme1) is less-loaded and seems to have the same
number
> of hops to my most common destinations.  So, generally speaking, I'd
like
> all traffic to use hme1.

> However, checking netstat -i tells me that hme1 is rarely used.
netstat -nr
> tells me that hme1 is used for a very small subset of my destination
> addresses.  Confusingly enough, the 'default' destination in the
routing
> table does not have an entry in the 'Interface' column.

> So, specifically, how can I tell my machine to be more liberal with
hme1?
> Since I imagine this will mean specifying destination addresses that
should
> use that interface in the routing table, what criteria should I use in
> choosing the destination addresses that use hme1?  Also, why is no
interface
> named in the 'default' destination row of my routing table?

> Last, can anyone suggest a good book on this subject so I can educate
myself
> further?

Man, I know your name from somewhere, if I could only place it!

My advice would be to disable the 10 Mbit card and run the fast
ethernet as your default (and only) interface. My guess is that
the only traffic going over your 100 Mbit card is traffic your
machine is routing!

1. remove the /etc/hostname.hme0 file
2. make sure that /etc/hosts and /etc/hostname.hme1 share a common name
3. put your router in /etc/defaultrouter
4. check that /etc/net/*/hosts all reflect the correct hostname
5. make sure /etc/netmasks is correct
6. reboot to make sure that hme1 comes up as the default (and only)
active interface.

Your card will auto-negotiate, so make sure that you're plugged into
a port capable of giving you 100 Mbit service or you'll step-down to
10 Mbit/sec.

--
-Andy M
http://synecdoche.net/~andy

did you play netrek ??

Sent via Deja.com http://www.deja.com/
Before you buy.

 
 
 

Configuring Routing Table with Multiple Interfaces

Post by aryz.. » Wed, 07 Jun 2000 04:00:00




Quote:> I'm trying to figure out how to set up my Sol 7 machine to use the
installed
> 100-Mbit interface.  I have followed leads from previous posts and a
> beginner's sysadmin guide that I have to the routing table.  However,
the
> documentation for how these things works is sparse and I'm afraid it
will be
> easy for me to do more harm than good.  That is where you
good-Samaritan
> types comes in.  ;)

> My 10-Mbit Ethernet interface (hme0) is on a heavily loaded network
and the
> 100-Mbit interface (hme1) is less-loaded and seems to have the same
number
> of hops to my most common destinations.  So, generally speaking, I'd
like
> all traffic to use hme1.

> However, checking netstat -i tells me that hme1 is rarely used.
netstat -nr
> tells me that hme1 is used for a very small subset of my destination
> addresses.  Confusingly enough, the 'default' destination in the
routing
> table does not have an entry in the 'Interface' column.

> So, specifically, how can I tell my machine to be more liberal with
hme1?
> Since I imagine this will mean specifying destination addresses that
should
> use that interface in the routing table, what criteria should I use in
> choosing the destination addresses that use hme1?  Also, why is no
interface
> named in the 'default' destination row of my routing table?

> Last, can anyone suggest a good book on this subject so I can educate
myself
> further?

If you absolutely have to use dynamic routing and listen to what
your router advertises, you certainly can play all sorts of tricks
using gated instead of routed or rdisc. With gated, you can specify
the metrics for each subnet in absolute or relative numbers.

Another (very dirty) hack I'd risk to suggest is to swap
the device links in /dev between hme0 and hme1, and rename
/etc/hostname.hme? correspondingly, in this case new faked hme0
will be configured as default.. Don't tell anyone that
I've suggested it :-(

Andrey

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Before you buy.

 
 
 

Configuring Routing Table with Multiple Interfaces

Post by Mimr » Wed, 07 Jun 2000 04:00:00


Hmm..  I guess there is no reason to tie a default route to a given interface.
Since the router must sit on the same subnet as either of the IPs that the NICs
are listening on, it'll just go to whatever appears first on the routing table.
For example, if the default route is IP.1 and hme0 is listening on IP.2, hme1 is
on IP.3 then all traffic will go through hme0 because it is the first entry in
the table.

Personally, either do away with 10MB entirely or put the 100MB NIC on a separate
subnet and set the default router to the router on the subnet that's different
from the 10MB NIC.




> >I'm trying to figure out how to set up my Sol 7 machine to use the installed
> >100-Mbit interface.  I have followed leads from previous posts and a
> >beginner's sysadmin guide that I have to the routing table.  However, the
> >documentation for how these things works is sparse and I'm afraid it will be
> >easy for me to do more harm than good.  That is where you good-Samaritan
> >types comes in.  ;)

>   Are the two interfaces on the same subnet or on different
>   subnets?

>   Is the "hostname" [ /etc/nodename ] tied to hme1 or hme0?

>   For some reason, the interface id is not in the output
>   of netstat -nr.

>   What kind of naming service do you use?  By any chance one
>   that gives answers that favor your 10Mbit interface over
>   the 100 Mbit one?

 
 
 

Configuring Routing Table with Multiple Interfaces

Post by Scott B. Drummond » Wed, 07 Jun 2000 04:00:00


[my original request to tell my Sol 2.7 machine to use the 100 MBit Ethernet
interface (hme1) instead of the default 10MBit interface (hme0) deleted.]

Quote:>  Are the two interfaces on the same subnet or on different
>  subnets?

Different subnet.

Quote:>  Is the "hostname" [ /etc/nodename ] tied to hme1 or hme0?

hme0.

Quote:>  What kind of naming service do you use?  By any chance one
>  that gives answers that favor your 10Mbit interface over
>  the 100 Mbit one?

The naming service definitely directs all traffic to my machine through
hme0, so I understand all incoming traffic to be initiated on hme0.  But
does this prohibit me from forcing outgoing traffic from using hme1?

So, any way I can tell out outbound traffic to use the hme1 interface
without having to change any external references to my machine (and hme0)?

Thanks,
Scott

 
 
 

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