Re: IPCP option for SIP server
James Carlson <[email protected]>
| Newsgroups | gmane.ietf.pppext |
|---|---|
| Message-ID | <[email protected]> |
Ashutosh Dutta writes: > > Karl, in a 3GPP2 environment where the client gets an IP address from > PDSN over PPP link, my PDSN acts like a NAS which is also a PPP > server, and I may not have a DHCP server in that case. A "DHCP server" is no more difficult than an IP node that can send and receive UDP packets. If you don't have that, then it seems unlikely to me that you've got a functioning IP network at all. Note that you don't need stateful behavior to solve the problem. A simple DHCPINFORM will do the trick. > I have used DHCP in LAN environment with SIP option. And that's a good reason why it should *not* be added to PPP. It's redundant work. A much better reason to avoid adding it to PPP is that it won't work right. Consider the following network: N1 <---PPP---> N2 <---Ethernet/other---> SIP server In this case, you'd want N1 to learn about the IP address of the SIP server that exists behind N2. But the PPP (and IPCP) negotiation on the PPP link terminates with N2. This means that N2 needs to somehow "know" that the SIP server exists and what its address is. This implies that either N2 behaves as a proxy between this new IPCP configuration option and DHCP, or that N2 has fragile statically configured data for that address. Either way, you're committing all of us (collectively) to producing new ad-hoc extensions to IPCP that are proxied one-by-one into DHCP or some local configuration that must be managed. That solution is far more complex and much less extensible than just having N2 behave as a generic DHCP/BOOTP relay on behalf of N1, and allowing those protocols to do what they're already designed to do. The same problem afflicts the ill-considered DNS name server address option, and I don't think we need to replicate that mistake. Once, I think, was plenty. -- James Carlson, KISS Network <[email protected]> Sun Microsystems / 1 Network Drive 71.232W Vox +1 781 442 2084 MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 781 442 1677 _______________________________________________ Pppext mailing list [email protected] https://www1.ietf.org/mailman/listinfo/pppext