On Tue, 15 Jul 2008, Hemant Singh (shemant) wrote:
Date: Tue, 15 Jul 2008 11:34:29 -0400 From: "Hemant Singh (shemant)" <shemant@cisco.com> To: "Stark, Barbara" <bs7652@att.com>, v6ops@ops.ietf.org Cc: Antonio Querubin <tony@lava.net> Subject: RE: Comments on draft-wbeebee-ipv6-cpe-router-01.txt Barbara, Since Antonio also raised a point about IPv6 addresses assigned to the WAN interface (and the number of WAN interface(s)), we are combining a reply to both you and Antonio. Barbara, when you say, "We have considered the possibility of a separate IP address for our TR-069 management of the CPE routers that we supply, but would want this to be a configurable option." could you please elaborate. Does this separate IPv6 address get assigned to the WAN side of the CPE Router? If yes, if the WAN interface is only assigned a link-local address, then what network interface on the WAN side does this IPv6 address get assigned to? One choice we have is to assign the IPv6 address to the Loopback interface facing the WAN side. Also, when reviewers ask for another network interface on the WAN side, or another IPv6 address on the WAN side, could reviewers please appreciate the fact that another WAN interface can mean two things for a router. Either we have second physical WAN interface with a new mac-address or we still have one WAN interface and the second WAN interface is just a logical interface bound to the physical WAN interface such that both the physical WAN interface and the logical interface share a mac-address between them. Antonio and Barbara, which one of these two interfaces are you talking about? Further, if one is spawning logical interfaces on any router, once doesn't have to stop at one extra interface. Go ahead and spawn more if one wants.
Actually the discussion is confusing because the 'WAN' interface appears to mean different things depending on whether the layer 2 modem is integrated into the CPE router. For discussion purposes, in a general network configuration where all the components are separate you'll have:
PCs
|
|
|
----- modem ----- switch ----- router/firewall ----- switch ----- PCs
1 A 2 B 3 C 4 D 5 E
Devices B and D are just plain ethernet switches. Although the focus of
this document seems to be on device C, it's interfaces, and the customer
devices (E) behind it, the CPE router being discussed potentially
encompasses functionality of devices A, B, C, and D.
In the case where the modem is integrated, the interface that internally links the modem to the internal router device C may or may not be accessible to the consumer via external physical ports. If they are physically accessible, they need a different name than "WAN" if "WAN" is defined to be 1 above.
If the modem is not integrated into your CPE device, then the "WAN" interface is just 2 and/or 3 above depending on whether additional "WAN" ports are provided by the vendor.
However these multiple definitions of WAN interfaces are confusing, hence my earlier suggestion of using different names for the modem-router interface and the access provider interface.
Further, Antonio, when you say, "Additionally, for those vendors that wish to integrate the layer 2 (DSL/cable) modem as part of the CPE router (where the "WAN" encapsulation is not ethernet), perhaps a separately named interface definition might be appropriate to avoid confusion with "WAN"." In such a case, the WAN interface is a logical interface that bridges the CPE Router to the broadband modem. We clarified the WAN interface definition as follows with new text WAN interface - a single physical network interface on the standalone CPE Router that is used to connect the router to the access network of the Service Provider. When the CPE Router is embedded in a device that connects to the WAN, this interface is a logical network interface that bridges the device to the CPE Router. Some devices which can have an embedded CPE router are: a cable or DSL modem, or a cellular telephone, etc. When we publish our next revision of the draft, we will include new text for the WAN interface definition.
How about this. If you want to tie the WAN interface to the internal router:
WAN interface - a network interface on the CPE Router that is used to connect the router to the access network of the Service Provider. When a CPE Router is embedded in a device that connects to the service provider via a non-ethernet connection, this interface is the logical interface that connects the internal router to the internal bridge. Some devices which can have an embedded CPE router are: a cable or DSL modem, or a cellular telephone, etc.
SPA (service provider access) interface - a non-ethernet physical network interface that is bridged to the WAN interface and directly connects to the access network of the Service Provider.
But if you want to keep the definition of WAN tightly coupled with the physical external port then something like this might be more suitable:
WAN interface - a network interface on the CPE Router that is used to connect the router directly to the access network of the Service Provider. When a CPE Router is embedded in a device that connects to the service provider via a non-ethernet connection, this physical interface is bridged to the router via an internal modem. Some devices which can have an embedded CPE router are: a cable or DSL modem, or a cellular telephone, etc.
WANEA (WAN Ethernet Access) interface - an optional ethernet interface that is bridged to the WAN interface and provides additional direct access to the Service Provider network.
You may want to call it something other than WANEA :) Antonio Querubin whois: AQ7-ARIN