Subject: RE: IP Unnumbered

From: vishwas <[email-masked]>
Date: Thu, 10 Dec 98 17:50:00 PST

> Pl. take a look at RFC 1812 Section 2.2.7

Now tell me why that needs kernel side support ? Its a matter of PPP
negotiation. The convention is you send 0.0.0.0 meaning "Give me an
address" they do likewise and both accept it.

You dont actually set the address your end to 0.0.0.0 but to match
another address you own (not loopback) and you add the routes via
route add blah netmask foo dev device

Alan

[vishu]
Alan my view point is not towards kernel support or wether or not linux   
supports this.
If I were to impliment this in IP/RIP How DO I do it. The problems are,
1) RIP 2 (draft-ietf-rip2-protocol-v2-06.txt) in section 5.4 clearly   
mentions that
Addressless links are not supported.

Even if we override this rule, how shall we go about in implimenting it.

Or if at all it is allredy possible in Linux, I would like to know w.r.t   
SLIP
Right now I configure SLIP like this,

/usr/sbin/slattach -d -v -p slip -s 19200 /dev/cua1 &
/sbin/ifconfig sl0 192.168.0.1 pointopoint 192.168.0.4 up
/sbin/route add -net 192.168.0.0  netmask 255.255.255.0 dev sl0

The first thing that arises is how not to assign an IP address to serial   
interface.
And then comes the IGP like RIP which says addreless links are not   
supported and how can we override this.

CISCO guys impliment this wether or not the other side of the P2P link   
supports IP Unnumbered or not.

I have few more queries w.r.t supporting this feature. How an application   
above IP like DVMRP or PIM will behave when running an IP Unnumbered   
interface...?

How much we gain how much we loose suppoerting this IP unnumbered   
feature..?

I still feel if properly subnetted we just loose 2 addresses for a P2P   
link, why at all use this if it has more drawbacks to offer.

Is the issue specific to EGP, where in 2 AS's are connected through a P2P   
link or it is applicable to IGP, too..?

What are the security risks if it were to be supported by RIP by   
overriding the protocol.

Alan, Fred and Malkin Pl. Comment this issue in Detain Please.

 -vishu

Regards
Vishwanath S. Edavayyanamath
 --------------------------------------------------------------------------  
 ------------------------
Software Engineer, Future Software Pvt. Ltd, Chennai, India
Ph : +91-44-4330550 (335)
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