[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [lwip-users] Sending to a non-local network without default netif se

From: HaaCee2
Subject: Re: [lwip-users] Sending to a non-local network without default netif set
Date: Fri, 14 Nov 2014 13:02:19 -0700 (MST)

On 14-11-14 20:27, Simon Goldschmidt [via lwIP] wrote:
HaaCee2 wrote:

> I am not entirely familiar with the ideas behind LwIP. But sourcebased
> routing is very much in line with rfc1122 (ip for hosts). I quote:
>> Under the Strong ES model, the route computation for an outgoing datagram
>> is the mapping:
>>                           route(src IP addr, dest IP addr, TOS) -> gateway
>> Here the source address is included as a parameter in order to select a
>> gateway that is directly reachable on the corresponding physical
>> interface. Note that this model logically requires that in general there
>> be at least one default gateway, and preferably multiple defaults, for
>> each IP source address.

Well, that excerpt is one of 2 possibilities in the RFC. The other
possibility is to do like lwIP does. I admit though that it looks kind
of strange sending packets with IP address A to the interface B just
because you have a matching destination gateway on that netif...
You are correct that it is only 1 of the 2 possibilities, and as indicated I am not familiar with the design of lwIP. So it's a perfectly valid choice NOT to support sourcebased routing.

By now, I'm tempted to add source-based routing as an option, although I
expect people using lwIP wih more than one interface being only a small
I beg to differ....
In my opinion the best approach to deal with vlans is to have multiple interfaces and then I think one is required to do sourcebased routing. Otherwise datagrams destined for a host on one vlan can be visible on another vlan (which is obviously undesirable).
Multiple stacks is a possibility here as well, but in embedded designs hardly an option....



lwip-users mailing list
[hidden email]

If you reply to this email, your message will be added to the discussion below:
To unsubscribe from Sending to a non-local network without default netif set, click here.

Erik van Veelen
AimValley B.V.
Utrechtseweg 38, 1213 TV Hilversum, The Netherlands
Tel: +31 35 689 1929, Fax: +31 35 689 1901
AimValley certificate http://www.aimvalley.com/aimvalley-ca-certificate-2007.crt

View this message in context: Re: Sending to a non-local network without default netif set
Sent from the lwip-users mailing list archive at Nabble.com.

reply via email to

[Prev in Thread] Current Thread [Next in Thread]