Na bazie naszych doświadczeń opowiem jak użycie BGP może wpłynąć na klaster budowany w oparciu o SDN oraz jak SDN może wpłynąć na dane przetwarzane przez BGP. Mam nadzieję zachęcić wszystkich słuchaczy do nieszablonowego myślenia przy projektowaniu sieci.

1. | BGP in SDN world — SDN in BGP world | © 2019 Akamai1

2. | BGP in SDN world — SDN in BGP world | © 2019 Akamai2
?
First thing that comes to mind
when you hear
SDN

3. | BGP in SDN world — SDN in BGP world | © 2019 Akamai3
?
First thing that comes to mind
when you hear
BGP

4. | BGP in SDN world — SDN in BGP world | © 2019 Akamai4
?
First thing that comes to mind
when you hear
router
Internet
autonomous system
routing
ISP
policy
peering
transit
AS_PATH
IP prefix
RFCOpenFlow
SD-WAN
controller
cloud
NFV
API
centralized
software
flowbuzz-word
data center
switch
BGPSDN

5. | BGP in SDN world — SDN in BGP world | © 2019 Akamai5
BGP in SDN world
SDN in BGP world
March 12, 2019

6. | BGP in SDN world — SDN in BGP world | © 2019 Akamai6
SDN in Akamai
new needs:
scalability (in “metro areas”),
hardware cost reduction,
and next generation
traffic engineering
= +
SDN

7. | BGP in SDN world — SDN in BGP world | © 2019 Akamai7
SDN in Akamai
fast rollout of
2nd version
1st version:
OpenFlow
poor vendor
support
BGP between
controller and
hardware

8. | BGP in SDN world — SDN in BGP world | © 2019 Akamai8
How can BGP
change your
SDN?

9. | BGP in SDN world — SDN in BGP world | © 2019 Akamai9
700k entries
in RIB
SDN
known flows
1st packet
in flow
BGP, policy
L3
computed RIB
BGP, policy,
net state
“Traditional” forwarding “Traditional” SDN Our SDN solution
message to a known destination
message to an unknown destination

10. | BGP in SDN world — SDN in BGP world | © 2019 Akamai10
BGP:
local pref➘ for backup
L3 L3 L3
VRRP
primary
controller
primary
& backup
machines
VRRP
backup
controller
primary
& backup
machines
BGP = consistency
Consistency & High Availability

11. | BGP in SDN world — SDN in BGP world | © 2019 Akamai11
How can
SDN
change your
BGP?

12. | BGP in SDN world — SDN in BGP world | © 2019 Akamai12
BGP-based SDN
Routing decision in SW
(centralized, custom TE)
“Traditional” BGP-based DC
Routing decision in HW
(BGP + ECMP, shortest path w/LB)
L3 L3 L3
L3 L3 L3
L3 L3 L3
BGP
BGP
L3
L2
L3 L3 L3
BGP:
pre-calculated paths
network state
future:
SDN-controlled spine-and-leaf

13. | BGP in SDN world — SDN in BGP world | © 2019 Akamai13
You’re not limited to IGP (or iBGP)
selecting path to next-hop
L3 L3 L3
overloaded
port
some destinations
are re-routed
some destinations
use old path
In-fabric Load Reshuffling

14. | BGP in SDN world — SDN in BGP world | © 2019 Akamai14
Reducing no. of Prefixes
• “L3 switches” on border
• Silicon doesn’t fit full routing table
• When useful?
• For predictable traffic
(e.g., caching CDN)
• When harmful?
• For anycasted servicesL3
BGP
sFlow
reduced no. of entries —
the most popular targets

15. | BGP in SDN world — SDN in BGP world | © 2019 Akamai15
Ingress Load Balancing
Policy?
• Simplest: path prepending
• Prepend to a peer or not?
• Don’t modify prefix
announcements too often!
network state
L3
policy
modified prefix
announcements

16. | BGP in SDN world — SDN in BGP world | © 2019 Akamai16

17. | BGP in SDN world — SDN in BGP world | © 2019 Akamai17
Business-oriented Routing
Best path selection?
• BGP-like
• Current link load
• Best performance
(feedback from Akamai
global traffic manager)
network state
L3
prefix
announcements
best path
selection

18. | BGP in SDN world — SDN in BGP world | © 2019 Akamai18

19. | BGP in SDN world — SDN in BGP world | © 2019 Akamai19
We Broke... BGP Tie Breakers
Paths from the same edge BGP
speaker have the same:
• originator ID
• neighbor address
edge BGP
speaker
central BGP
speaker
edge BGP
speaker
non-deterministic
best path
ADD-PATH ADD-PATH
ADD-PATH
unmodified BGP:
non-deterministic
best path

20. | BGP in SDN world — SDN in BGP world | © 2019 Akamai20
Nov ’18: one of the biggest
clusters in Akamai, 1.3 Tbps
Jul ‘18: take over an
existing cluster, 40 Gbps
Mar ‘18: bye bye OpenFlow
(one cluster – BGP, one decon’ed)
Jan ‘18: 3rd cluster
(BGP), 10 Gbps
Jul ‘17: decision
to move to BGP
May ‘17: 2nd cluster
(OpenFlow), 1 Gbps
Oct ‘16: 1st cluster
(OpenFlow), 5 Mbps
Trust
and
Delivery
Stay tuned! :-)

21. | BGP in SDN world — SDN in BGP world | © 2019 Akamai21
What have I learned?
• BGP can be a “SDN protocol”
• BGP is not limited to what
hardware offers
• Think out-of-the-box and have fun!
:-)
Piotr Wydrych
<piotr.wydrych@akamai.com>