From: asadovnikov (asadovnikov@comcast.net)
Date: Sat Sep 06 2003 - 02:26:53 GMT-3
The difference between PFC and PFC2 is that the first does MLS (much like
5500 NFFC) and the second does dCEF. In either case though if hardware can
not switch a packet, then the packet is punted to MSFC and processed from
that point as usually in the router, i.e. the MSFC CEF path would be tried
first, and if cef switching is not possible then next slow path would be
used.
You are right, the percentage of packets switched on MSFC is extremely
small, so it would not make statistically noticeable difference (or else you
have a performance issue).
I know that 6500 switching path is complicated, especially keeping in mind
that it is different for every supervisor hardware, and it is simply not
possible to put all details into a short email.
Best regards,
Alexei
-----Original Message-----
From: Mike Williams [mailto:ccie2be@swbell.net]
Sent: Friday, September 05, 2003 11:34 PM
To: 'asadovnikov'; 'Hugo Padilla Prad '; 'Brian McGahan'; 'zhang-meng';
'Ccielab (E-mail)'
Subject: RE: Cisco 6506 and BGP problem
Good call on this. And to the poster who posted the section about how the
MSFC can only do per-packet CEF in software....... Very interesting.....
If there's not a L3 switching entry on the PFC2 (it specifically mentioned
the PFC2, not the PFC... Dunno why) then CEF on the MSFC can handle the
packet, however, it occurs to me that CEF load balancing won't get a chance
to work because after the first packet is handled by CEF on the MSFC, then
the PFC will have a L3 switching entry for it, and would take it from there
for the rest of the flow..... Wow.......
Mike W.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
asadovnikov
Sent: Thursday, September 04, 2003 11:13 PM
To: 'Mike Williams'; 'Hugo Padilla Prad '; 'Brian McGahan'; 'zhang-meng';
'Ccielab (E-mail)'
Subject: RE: Cisco 6506 and BGP problem
Most of the packets are not switched by MSFC. The actual packets are
switched wither by PFC (or DFC). Depending on hardware PFC would either do
distributed CEF or mls flow switching. I trust in either case PFC hardware
will not be able to do per-packet. I do not dispute the idea though - on
average per source-destination pair loadbalancing should provide as good
distribution (and may even be better as it less likely to put the packets
out of the order).
Best regards,
Alexei
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Mike
Williams
Sent: Thursday, September 04, 2003 11:28 PM
To: 'Hugo Padilla Prad '; 'Brian McGahan'; 'zhang-meng'; 'Ccielab (E-mail)'
Subject: RE: Cisco 6506 and BGP problem
I don't see why it wouldn't. If you're using and MSFC/MSFC2 you can use CEF
for load balancing or even just equal-cost path load balancing (I'm using
Native IOS but I'm sure that running IOS on an MSFC on a 65xx in Hybrid mode
would use these features are they're IOS based). I think Brian's idea is a
perfect idea that's both simple and effective.
Mike W.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Hugo
Padilla Prad
Sent: Thursday, September 04, 2003 10:09 PM
To: 'Brian McGahan'; 'zhang-meng'; 'Ccielab (E-mail)'
Subject: RE: Cisco 6506 and BGP problem
Brian,
My understanding is that 6506 doesn't support per-packet load balance.
Regards,
-Hugo
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brian McGahan
Sent: Thursday, September 04, 2003 10:18 AM
To: 'zhang-meng'; 'Ccielab (E-mail)'
Subject: RE: Cisco 6506 and BGP problem
Meng,
Why not just put two static default routes? With CEF you can load
balance between these routes on a per-packet or per-destination basis.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-334-8987
Direct: 708-362-1418 (Outside the US and Canada)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
zhang-meng
Sent: Thursday, September 04, 2003 4:02 AM
To: Ccielab (E-mail)
Subject: Cisco 6506 and BGP problem
Hi: Group
A problem, I want to use 6506 (with layer 3 function) to connect with
two ISP(using two 1000BaseT port) load balance, but Tel can't support BGP,
they worried statibility.
What kinds of solution and Could you give some suggestion and design.
Regards
Meng Zhang
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