[comp.sys.hp] router

mab@ntcsd1.UUCP (Mark Bradford) (12/05/89)

We have a model 9000/840 running hp-ux 3.1.  After the system is
rebooted, and a netstat -r is executed we get the following output

Routing tables
Destination     Gateway         Flags    Refcnt Use        Interface
default         ntcsd1          U        2      8579       lan0
127             127.0.0.1       U        2      10039      lo0
128.1           ntcsd1          U        9900   278468     lan0


A little while later, we get the following output.  To my knowledge
there are no application programs that screw around with the routing
tables.

Routing tables
Destination     Gateway         Flags    Refcnt Use        Interface
128.1.1.7       g5002           UGH      1      544        lan0
128.1.1.8       g5002           UGH      0      14         lan0
rtpuxd          g5002           UGH      0      322        lan0
default         ntcsd1          U        2      8626       lan0
127             127.0.0.1       U        2      10057      lo0
128.1           ntcsd1          U        9900   279233     lan0

Are there any places, other than netlinkrc, that update the routing
tables.  

PS  We are in the process of making our IP addresses conform to Internet
standards.

lyle@hpindda.HP.COM (Lyle Weiman) (12/06/89)

>> Are there any places, other than netlinkrc, that update the routing
>> tables.  
>> 

The routing table can also be affected by ICMP Redirects.  When a Redirect
arrives, directing this machine to send packets destined for a certain address 
via a certain gateway, a routing table entry with those values is created.
Thus, it can happen that, over time, additional entries are made to the table.

Redirects often are generated by gateways which receive packets from a host,
but find (thru their own tables, routing protocol-derived information, etc.)
that there is a "better route" to that host.  When this happens, they still
forward the original packet, but they send an ICMP Redirect to the sending
host, informing it that a better route exists.  HP systems, as of about
release 2.0, have made use of these Redirects."

These new entries are definitely from redirects, as they are each for a
single host, rather than for a network.

Your posting specifically mentioned a 3.1 system, but I thought I'd just
quickly mention that Release 7.0 adds the capability to run /etc/gated,
which "understands" routing protocols (RIP, HELLO, and IGRP).  gated
can and does affect the routing table entries.

raj@hpindwa.HP.COM (Richard Jones) (12/06/89)

>Are there any places, other than netlinkrc, that update the routing
>tables.  

Yes, I believe that when the UX box receives an ICMP Redirect message,
the new gateway will be added so that later connections will start
life using the right gateway.  Generally speaking, the host will receive 
the redirect when it attempts to route packets thru a gateway that
thinks that a different gateway would be a better idea...

rick jones
MPE/XL Network Type
standard disclaimers

lyle@hpindda.HP.COM (Lyle Weiman) (12/14/89)

I must apologize for an error in my previous posting:

>> Your posting specifically mentioned a 3.1 system, but I thought I'd just
>> quickly mention that Release 7.0 adds the capability to run /etc/gated,
>> which "understands" routing protocols (RIP, HELLO, and IGRP).
                                                          ^^^^

This should have said EGP (the Exterior Gateway Protocol), not IGRP.  I
regret any inconvenience this may have caused.

--lyle weiman