Standard IP routing

[Boske]

Hi Guys, just a simple question going to the standards of IP routing :

If a router has 2 networks connected to 2 different WAN ports

What will the router decide when he has 2 default gateways configured in his routing table (without the use of any advanced routing protocol, just standard static routing), each pointing to one of the WAN networks

will he :
- switch between these 2 gateways (and perform a sort of loadsharing/balancing), so forwarding each packet to a different gateway
or
- will he forward the packets to the first entry he finds in his routing table ? and always using the same gateway.

Regards

J.

 

[jimbopalmer]

The RV042 dual WAN router can do fail over or weighted load balancing. You can also pin certain ports to one WAN or the other. If you pin 443 to one WAN, your SSL connections all use that WAN, etc.
Other Dual WAN routers I have used have even more options. My defunct Webramp allowed you to make additional WAN connections as load increased. (it used 3 56k modems, before broadband)

I tried to remain child-like, all I acheived was childish.

 

[Boske]

Hi Jim, thanks for your reply (checked the proposed router). But in fact my question was just about TCP/IP routing standards without any hardware/software aid : what will a routing process do when it sees that it has 2 default gateways in it's routing table (tried to look it up via an RFC, but could not find it)

I think it will just forward the packet to the first entry it encounters in the routing table, and will (as a standard) never use the second entry. This because the program will jump out of the tabel as soon as it encounters the first hit.

But i'm not sure about this. Hope someone can give me the correct information ?

 

[VinceWhirlwind]

I would say it depends on the OS.

UNIX people have told me in the past that in the situation you describe, the two default routes will be used alternately. I'm sure I've played with it on Cisco and other gear but I have no recollection about how it acually behaves.

One thing to remember is that it's not correct to say that the routing table is read as you describe (in the same way as an access list), because the actual routing isn't done by the routing table. The routing table is just where routes are configured (manually or using routing protocols). Actual routing of packets is no longer done by referring to the routing table.

 

[Boske]

Hi Vince, Thanks for your reply. You don't know about any RFC that is describing the routing process ?