[c-nsp] ME3600 BGP Route-Maps and IPv6 (WAS: Re: preference on bgp route advertisements)

[Gert Doering]

Hi,

On Thu, Mar 08, 2012 at 12:34:52PM +0000, Phil Mayers wrote:
> >Now *that* brings me to another favourite soapbox rant :-) - why oh why
> >is "tag" not supported on connected routes?
> 
> Interesting question. Where would the "tag" go? On the whole interface 
> (what about "ip ... secondary") or on the IP/IPv6 address?

On the "ip address" thing, because I might want to tag things differently,
like "this needs to get a different BGP metric than that one" (which is
something we currently do with prefix-lists to get around the HSRP-slave
annoyance...).

> >(Along with "why is there no way to make HSRP-slave interfaces really
> >passive, not showing up in the local FIB and in 'redist connected'
> >etc?"...  none of this is "my network will stop working if I can't have
> >that!" critical, but it would save oh so many workarounds).
> 
> I do still pine for the Extreme ESRP model (separate ethertype PDUs used 
> to determine master/slave status, slave shuts down all layer3 and layer2 
> [except control PDU] forwarding). Solves spanning tree and return-path 
> asymmetry at a stroke. It would be nice to have that option in Cisco-landia.

Well, using a separate ethertype PDU might simplify this somewhat from
the control-plane PoV ("I can't send HSRP packets to an IP interface that
is down"), but since the HSRP/VRRP packets are sent to a multicast 
address anyway, and not to anything bound to that interface IP config,
it should not pose unsolvable problems either.

It's more a "nobody said they would buy $millions of devices if we 
implement this" thing  (and *then* they would only implement it for
the specific platform ordered, in the specific operating-system of the
week used there)...

I'm not sure if cisco internal software development has "protocol owners"
(like "this person decides what gets added to BGP, that person decides
about HSRP and VRRP"), but this sort of feature is something the protocol
owner would need to see the need for, and then get it pushed through *all*
the BUs.

gert
-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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