Subject: ttl = 255 and scope limited to lan ..why?

From: Vikram <[email-masked]>
Date: Fri, 20 Jul 2001 08:50:52 -0700 (PDT)

hi folks,

RFC says that ttl shld always be set to 255 in vrrp pkt. and also that
the scope of each VR is restricted to a single lan. If that is the case
wouldnt it better if the ttl was set to 1 instead? The backup will
always be in the same lan so it will recieve the pkt nonetheless.

Thanks

Regards,
Vikram

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From: Peter Hunt <[email-masked]>
Date: Fri, 20 Jul 2001 09:49:52 -0700

> wouldnt it better if the ttl was set to 1 instead?

It's possible that a packet with ttl of 1 originated from more than 1
hop away. So it would be possible to inject protocol packets from another
network.

By requiring a ttl of 255, you can ensure that protocol packets weren't
forwarded from another network.

	Peter.

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From: Vikram <[email-masked]>
Date: Fri, 20 Jul 2001 10:25:32 -0700 (PDT)

well if you send out pkts with ttl=1 in first place, it will not travel
more than one hop anyways. 

Also if you are a multicast router then you shhould never forward a
datagram with addresses of 244.0.0.x as destination,regardless of ttl. 

So the possibility of originating from more than one hop away doesnt
exist ie receving a misconfigured packet.

And besides,the vrrp pkt shld also clear numerous other checks to be
accepted as a valid vrrp pkt- ie Authenication issues.

Vikram

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