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https://github.com/s3u/anycast-loadbalancing
A demo of anycast based load balancing without load balancers
https://github.com/s3u/anycast-loadbalancing
Last synced: 3 months ago
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A demo of anycast based load balancing without load balancers
- Host: GitHub
- URL: https://github.com/s3u/anycast-loadbalancing
- Owner: s3u
- Created: 2015-12-29T08:09:32.000Z (almost 9 years ago)
- Default Branch: master
- Last Pushed: 2015-12-29T09:21:45.000Z (almost 9 years ago)
- Last Synced: 2024-06-03T09:38:41.432Z (5 months ago)
- Language: Shell
- Homepage:
- Size: 13.7 KB
- Stars: 11
- Watchers: 2
- Forks: 5
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
The topology in this experiment demonstrates anycast based loadbalancing using a set of BGP
peered routers, servers, and clients. All the routers use Quagga for BGP. The technique here
is similar to Cloudflare's
[Load Balancing without Load Balancers](https://blog.cloudflare.com/cloudflares-architecture-eliminating-single-p/).
## Prerequisites
1. Vagrant
2. Cumulus Linux: Follow steps at [Setting Up the Vagrant Environment](https://docs.cumulusnetworks.com/display/VX/Using+Cumulus+VX+with+Vagrant#UsingCumulusVXwithVagrant-SettingUptheVagrantEnvironment)
to download and add Cumulus Linux vagrant box.
I use Cumulus Linux here as support for flow based multipath routing is lacking in kernels shipped
with commodity Linux distros.
## Getting Started
```
git clone https://github.com/s3u/vagrant-anycast-bgp.git
cd vagrant-anycast-bgp
vagrant up
```
Make the following change to fix the interfaces to work around bug in Vagrant provisioning of
Cumulus Linux 2.5.5,
1. `vagrant ssh cr1`
2. `sudo vi /etc/network/interfaces`
3. Add `netmask 255.255.255.0` for interfaces `swp1`, `swp2`, `swp3`.
4. `sudo service networking restart`
Wait for a few seconds to get the routing table updated.
```
vagrant@cr1:~$ ip ro
default via 10.0.2.2 dev eth0
10.0.2.0/24 dev eth0 proto kernel scope link src 10.0.2.15
10.10.12.0/24 dev swp2 proto kernel scope link src 10.10.12.11
10.10.13.0/24 dev swp3 proto kernel scope link src 10.10.13.11
10.20.1.0/24 dev swp1 proto kernel scope link src 10.20.1.11
10.20.2.0/24 via 10.10.12.12 dev swp2 proto zebra metric 20
10.20.3.0/24 via 10.10.13.13 dev swp3 proto zebra metric 20
10.30.1.3 proto zebra metric 20
nexthop via 10.10.12.12 dev swp2 weight 1
nexthop via 10.10.13.13 dev swp3 weight 1
```
The last three lines show the routes to our anycast server.
## Topology
The above steps bring up the following nodes:
1. cr1: A Cumulus Linux 2.5.5 router that client nodes u1 and u2 use as the gateway.
2. r2 and r3: Two Ubuntu 14.04 routers peering with cr1 via BGP.
3. s1: Server with anycast IP of `10.30.1.3` with r2 as the default gateway.
4. s2: Server with anycast IP of `10.30.1.3` with r3 as the default gateway.
5. u1 and u2: Test clients
Both s1 and s2 run nginx that prints the hostname in response to a `GET`.
## Tests
Open two terminals and try the following in each.
```
# Terminal 1
vagrant ssh u1 -c "while true; do curl 10.30.1.3;done"
# Terminal 2
vagrant ssh u2 -c "while true; do curl 10.30.1.3;done"
```
Note these two printing `s1` or `s2` in a loop.
While this is going on, suspend r2 to see clients continue to get traffic served.
```
vagrant suspend r2
```
Both terminals start printing `s2` as `s1` is no longer reachable. Then `vagrant resume r2` and
`vagrant suspend r3` to see both terminals print `s1`.
These tests demonstrate two things:
1. Traffic balanced between the servers s1 and s2
2. Graceful failover without middle boxes
In the real-world you would write a healthchecker to detect failures of our anycast nodes and
withdraw their routes from upstream routers. This is entirely programmable.
## Credits
This setup is a fork of [https://github.com/d-adler/vagrant-anycast-bgp](https://github.com/d-adler/vagrant-anycast-bgp),
but extended to demonstrate multipath routing for load banalcing.