Loose Source Routing

Wed Mar 7 17:22:10 UTC 2001

> Now, LSRR is _expensive_.  Modern routers handle packets with options in
> hardware, and doing IP options in hardware is not cheap.

Conveniently, not very many of them are sent.

> (BTW, what other options are actually used? :)  IMO, prohibiting IP
> options altogether would be a good idea (and don't ask me about
> fragmentation).

I use the timestamp option sometimes.
And the record route (no source routing) option.

I do suspect that I'm one of a very small set with respect to the
former, however.

> As for debugging routing - isn't it much better to ask OFRVs to add
> remotely accessible traceroute servers to their boxes? There is no
> engineering or economic justification for diagnostic fucntionality like
> LSRR to stay anywhere close to the fast packet path.

While this might be nice in theory, I think that it would be a political
nightmare to deploy. Thus leaving us with the status quo.

It also has nasty state implications.

--jhawk