You're right, I was missing that. Thanks. ________________________________
From: Anand Kanagala [mailto:[EMAIL PROTECTED] Sent: Wed 5/16/2007 16:55 To: Egi, Norbert Cc: [email protected] Subject: Re: [Click] Sample IP router configuration: ARPQuerier + SetIPAddress? LookupIPRoute (from the thesis) will replace the destination ip annotation with the ip addres of the gateway. See http://www.read.cs.ucla.edu/click/elements/radixiplookup for an explanation. On 5/16/07, Egi, Norbert <[EMAIL PROTECTED]> wrote: > Hi, > > I'm creating a multiple forwarding path IP router configuration by extending > Eddie Kohler's sample IP router configuration shown on page 64 in his PhD > thesis. It looks to me that this configuration is a little bit incomplete. My > concern is about packets destined to an IP address multiple hops away. In > this case, the destination address annotation will be set to this address by > the CheckIPHeader element and based on this annotations the ARPQuerier will > send out a request for the MAC address of this IP, but as it is far away (not > on the LAN the interface is attached to) no answer will arrive. Thus, the > packet won't go anywhere. > > I think what is missing from that configuration compared to Linux's basic > routing is the next-hop's IP address (i.e. the gateway to that destined > network). As far as I understand the operation of the whole sample > configuration, this could simply be solved by putting a SetIPAddress element > with the proper next-hop's IP address as argument after the IPLookup element > and probably the entries in the IPLookup will have to be sorted a bit > different, as packets leaving on the same interface but going to different > next-hops have to go through different SetIPAddress elements. As a > consequence, by the time the packet arrives at the ARPQuerier it will always > have the next-hop's IP address in its destination address annotation rather > than the 'final' destination address, which can definitely be resolved by the > ARPQuerier. > > My question is whether I'm right on this destination address annotation and > ARPQuerier issue or I'm missing something? > > As far as I understand, the ARPQuerier sets the SRC MAC address to the one it > has in its argument and sends out a request if it doesn't have the MAC for > the IP address in the destination address annotation. When the response > arrives it puts that MAC in the destination field of Ethernet header and > emits it on its output. > > Thanks in advance, > Norbert > > _______________________________________________ > click mailing list > [email protected] > https://amsterdam.lcs.mit.edu/mailman/listinfo/click > _______________________________________________ click mailing list [email protected] https://amsterdam.lcs.mit.edu/mailman/listinfo/click
