FIB table saving technique (with simple virtual aggregation)

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FIB table saving technique
(with simple virtual aggregation)
PLNOG Warszawa - Marzec 2011
Cisco Systems
Robert Raszuk, raszuk@cisco.com
Nana Ogawa, naogawa@cisco.com

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• ookubo@sakura presentations at IRS 20090914
Mesurment RIB hit rate on real traffics
Very low hit rate
99% traffics hit 3.67% tables
• Default route check by Randy bush
But bad manner with default route at upstream edges

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R R
Customer Site
EBGP EBGP
IBGP
IBGP
EBGP
ISP X ISP Y
R FULL
FULL
BGP
RIB/FIB
Internet

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R-C R-D
R-E
Customer Site
FULL +default
FULL
FULL
BGP
RIB/FIB
FULL
FULL
default + α
R-F
R-A R-B
EBGP
IBGPIBGP
FULL
EBGP
ISP X ISP Y
FULL
Route Next hop Best path
0.0.0.0/0 R-D ✓
A R-C
R-D ✓
B R-D ✓
C R-C
R-D
✓
D R-C ✓
BGP Table
Aggregate to
default route
Route Next hop
0.0.0.0/0 R-D
C R-C
D R-C
RIB/FIB
A, C, D A, B, C
default
Internet

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R-C R-D
R-E
Customer Site
FULL +default
FULL
FULL
BGP
RIB/FIB
FULL
FULL
default + α
R-F
R-B
EBGP
IBGPIBGP
FULL
EBGP
ISP
FULL
Route Next hop Best path
0.0.0.0/0 R-D ✓
A R-C
R-D
✓
✓
B R-C
R-D
✓
✓
BGP Table
Route Next hop
0.0.0.0/0 R-D
A R-C
R-D
B R-C
R-D
RIB/FIB
A, B
default
Internet
Default route from R-C is
also needed to be
suppressed Path A and B.

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• Conditions for aggregation
-monitors the default routes in the main BGP table.
-If default route is installed in RIB and FIB, it suppresses any more
specific route to be installed in RIB and FIB, if the next hop is the same
as default route.
-if multipath is enabled, only when two default would be coming via the
same next-hop as that of multi-path, the specific multipath would be
suppressed.
• Simple configuration
router bgp xxx
table-map <route-map name> simple-va
• This implementation is based on IETF draft, but not totally same.
http://tools.ietf.org/html/draft-ietf-grow-simple-va-01
RIB/FIBAggregate to
default route
BGP

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EBGP
IBGP
IBGP
IBGP
DIX-IE (IX)
EBGP
Verio (ISP)
Internet
EBGP
C3825
394 routes 306,620 routes
46 routes
1 route
WIDE network
ISPs
IBGP
eBGP peers EBGP
eBGP peers
BGP route RIB/FIB route Memory taken by
BGP and RIB/FIB
Before 307,061 307,041 230 MB
After 307,061 429 73 MB
Reduce about 160MB memory

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va-eft@cisco.com
• It can save a lot of small routers from having their data plane
overflow by lots of internet routes.
• The real saving here would be normally also in the amount of
FIB on line cards in distributed systems ( ex. cat6k) as well as
significant reduction of IPC traffic
• In next phase we could do the same for other aggregates ..
not only for default route. But for now this is what we have
discussed and agreed up on.
• Tell us that this feature is useful or not….
• You can encourage your vendor to implement this feature.

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• Ookubo-san report IRS21
http://irs.ietf.to/
• Randy’s report
http://www.janog.gr.jp/meeting/janog24/program/st3.html
• IETF draft
http://tools.ietf.org/html/draft-ietf-grow-simple-va-01

11. Thank you.