Optimizing Traffic
Flow with Akamai
Eric Leung
Akamai Technologies

1© 2023 Akamai

AgendaAkamai Introduction•Akamai deployment in South Asia

How Akamai map traffic••

Different types of Akamai Clusters
Why most of the BGP Traffic Engineering techniques doesn’t work with Akamai

Best practices and Recommendations
•
•
•

2

Setup own DNS resolvers
Maintain complete and consistent route announcements
Do not filter traffic© 2023 Akamai

Akamai deployment in South Asia
Afghanistan: Bangladesh: Dhaka
Bhutan: Thimphu
India: 40 cities
Maldives: Nepal: Kathmandu
Pakistan: 6 cities
Sri-Lanka: Colombo3© 2023 Akamai

How Akamai works: Some facts
Are Akamai clusters backbone connected to each other?
Most of the Akamai clusters are operated independent, and not talk to each others.
Where does the content Akamai serve come from?
Akamai operates a caching infrastructure
Each cluster has full Internet connectivity to obtain content from the original website
or mid-tier servers.
How does Akamai direct users to its cluster?
Akamai maps users via a multi level DNS server architecture4© 2023 Akamai

How Akamai works: Cluster types
Private: Clusters dedicated to specific networks or their downstream ISPs. Role: Edge
Clusters inside the network partner: AANP - Akamai Accelerated Network Partner
Public: Clusters shared by multiple networks. Role: Edge, Mid-Tier and Infrastructure
Clusters inside some public facility, connecting to multiple networks via PNI, IXs and Transit providers.
PrivateClusterContentOrigin

PublicCluster
IX

Transit Network

PrivateCluster

End users
5© 2023 Akamai

sitnTra

ISPNetwork
PrivateCluster

PNI

PublicCluster

PublicClusterHow Akamai works: Cluster roles - Edge
1. Edge: Cache the content and distribute to the end users
PrivateClusterContentOrigin

PublicCluster
IX

Transit Network

PrivateCluster

sitna
Tr

ISP
NetworkEnd users

6© 2023 Akamai

PrivateCluster

PNI

PublicCluster

PublicCluster

How Akamai works: Cluster roles - Edge
1. Edge: Cache the content and distribute to the end users
when there is cache miss,clusters will fetch the content form the Origin

PrivateClusterContent
OriginPublicCluster
IX

Transit Network

PrivateCluster

sitna
Tr

ISP
NetworkEnd users

7© 2023 Akamai

PrivateCluster

PNI

PublicCluster

PublicCluster

How Akamai works: Cluster roles – Mid-Tier
2. Mid-Tier: Parent Cache the content and distribute to Edge clusters
PrivateCluster

Improve origin offload and protection
Bring the origin closer to the EdgeContentOrigin

PublicCluster
IX

PrivateCluster

Transit Networksitna
Tr

ISP
Network

PNI

End users
PrivateCluster8© 2023 Akamai

PublicCluster

PublicClusterWhy most of the BGP Traffic Engineering
techniques don’t work with Akamai?

•••

9© 2023 Akamai

AS Path Prepending
MED
More/less Specific Route advertisement

Akamai maps traffic to a cluster based on …
1. Network performance (Latency, packet drops, link utilizations)
2. Server capacity
3. Cache placement policy
Private
4. Cache serving policy
Cluster

PublicCluster
Transit NetworkIX

PrivateCluster

sitn
aTr

ISP
Network
End users

10© 2023 Akamai

PNI

PrivateCluster

PublicCluster

PublicCluster

Akamai does not map traffic to a cluster based on …
AS path length, so AS Path prepending is not always working
PrivateCluster

PublicCluster
Transit NetworkIX

PrivateClustersitn
TraX

ISPNetworkEnd users

11© 2023 Akamai

PNI
PrivateCluster

PublicCluster

PublicCluster

Prepending 2x AS

Akamai does not map traffic to a cluster based on …
MED value, so changing MED value is not always working
PrivateCluster

PublicCluster
Transit Network

PrivateCluster

100IX

sitn
Tra

IX

ISP
NetworkEnd users

12© 2023 Akamai

10
PrivateClusterX

PublicClusterxx

PublicCluster

Different MED value

Akamai does not map traffic to a cluster based on …
prefix length, so advertising specific route is not always working
PrivateCluster

PublicCluster
Transit NetworkIX

PrivateCluster/23

sitnTraPNI XISPNetworkEnd users

13© 2023 Akamai/24
PrivateCluster

PublicCluster/xx

PublicCluster

Different Prefix Length

Sometime bgp based traffic engineering seems working
in case both paths are reachable from the same cluster

Transit Network #1(lower latency)

Cluster#2

Cluster#1

ISP
Network

Transit Network #2(higher latency)

End users
Apply TE to de-prefer Transit Network #1

14© 2023 Akamai

Sometime bgp based traffic engineering seems working
in case both paths are reachable from the same cluster, the router of that cluster willreroute the traffic as the best-path has been changed

Transit Network #1(lower latency)

Cluster#2

Cluster#1

ISPNetwork

Transit Network #2(higher latency)

End users
Apply TE to de-prefer Transit Network #1

15© 2023 Akamai

Sometime bgp based traffic engineering seems working
in case both paths are reachable from the same cluster, the router of that cluster willreroute the traffic as the best-path has been changed
However, Akamai mapping may then change the serving cluster to #2 as its
performance is now better…
Transit Network #1(lower latency)

Cluster#2

Cluster#1

ISPNetwork

Transit Network #2(higher latency)

End users
Apply TE to de-prefer Transit Network #1

16© 2023 Akamai

Why don’t these techniques have the usual effect?
• Akamai use BGP to learn routes so as to determine which clusters are eligible to serve whattraffic• Akamai uses Mapping to determine which cluster to serve the traffic• Akamai nodes are mostly isolated; there is no backbone between them
• Akamai uses multiple criteria to choose the optimal node / server• These criteria include standard network metrics:Latency
Throughput
Packet loss17© 2023 Akamai

Akamai suggestions to ISPs
• Please accommodate our best practices and recommendations to enable the Akamai mapping
system to make optimal decision• Feel free to contact us if you wish to change the way traffic being sent to you• We can work together on optimization traffic flow18

© 2023 Akamai

Best Practices and Recommendations

••
•

19

© 2023 Akamai

Setup own DNS resolvers
Maintain complete and consistent route announcements
Do not filter trafficSetup own DNS resolvers
Akamai CDN map traffic based-on DNS resolvers external IPs• Use anycast IPs for user-facing DNS resolver IPs• Use different external IPs for users in different locations• Setup ACL to only allow your own users to use your DNS resolvers
If not possible to setup your own DNS resolvers, then• Use Google DNS (8.8.8.8 / 8.8.4.4, 2001:4860:4860::8888 / 2001:4860:4860::8844)• Use OpenDNS (208.67.222.222 / 208.67.220.220, 2620:119:35::35 / 2620:119:53::53)• Akamai support EDNS Client Subnet (ECS) for Google DNS and OpenDNS• Publish GeoFeed IP location information in RFC8805 format
Maintain good Internet connectivity to your DNS resolvers• Akamai may use your DNS resolvers external IPs for performance monitoring• Alternatively, you may provide Akamai with your desire IPs for performance monitoring20© 2023 Akamai

Maintaining Complete and Consistent RouteAnnouncements
Announce complete prefixes to Akamai• Includes both DNS and end user IPs• Akamai map traffic based-on DNS to the optimal node, then send user traffic from there• Inform your downstreams to announce all prefixes to youIf not possible to announce all prefixes, then
• Akamai may block your whole ASN prefixes, to avoid suboptimal performance
Maintain consistent route announcement to your peers / upstream providers• Akamai may send overflow traffic from your upstream providers

21© 2023 Akamai

Do not filter traffic
Carry traffic that you announce• If you promised to carry the traffic of an IP block (e.g., /20), you should not have any holes••(e.g.,/24) or drop any part of the traffic
Akamai routers may not have the full Internet routing table
The end user's connectivity will be impacted!!!

Performance monitoring• Akamai uses IPs in your network as performance monitoring• If possible, avoid filtering or rate-limiting ICMP to your network• Send return traffic to Akamai closet location to maintain lowest latency

22© 2023 Akamai

SummaryAkamai Intelligent Platform• Highly distributed edge servers• DNS-based mapping CDN
Optimizing Traffic Flow
• Typical BGP traffic engineering techniques doesn’t work
• Collaborate with Akamai for traffic engineering
Best practices and Recommendations• Setup your own DNS resolvers• Maintain complete and consistent route announcements• Do not filter traffic23© 2023 Akamai

Questions?
Eric Leung <taleung@akamai.com>
More information:
Peering: https://as20940.peeringdb.com

24© 2023 Akamai