1. Introduction to dynamic routing on Linux with Quagga
FVLUG – July 23, 2007
Wim Kerkhoff –

2. Overview Short introduction to dynamic routing Introduce Quagga
Installing Quagga on Debian
Example Quagga configurations
Demo
Using Quagga in production

3. Static Routing Simplist and most common method
Manually configured by humans
Can’t handle network changes such as outages
Doesn’t scale with many network devices
Requires least amount of expertise
Generally used on hosts (PCs, printers, etc) and simple NAT routers

4. Dynamic Routing Protocols
Applications that automatically discover network destinations
First they learn what network routes are directly connected
Then chat with neighbouring routers to learn what they know
The entire network learns about changes within minutes or even seconds
Generally used on Internet backbone routers and in organizations with many routers

5. Common routing protocols
RIP – old one, based on hop count. Timer system can result in slow convergence
OSPF – also uses multicast. Calculates shortest path using costs assigned to each link. Easy to setup but less knobs then BGP. Used inside organization
BGP – uses TCP session. Can do filtering, route-maps, mangling, etc. Normally used for communicating with other organizations and based on policy

6. Remember: Routing != Forwarding
Routing directs forwarding
Routing is the process of selecting paths in a network
Forwarding is the relaying of packets through one network segment to another by nodes
So a network device can perform routing, forwarding, or both
So you’ll have a broken router if /proc/sys/net/ipv4/ip_forward is set to 0 even with a beautiful quagga config

7. What is Quagga? Open source routing software
Forked 4 years ago from Zebra to form a much better and healthier de-centralized community
Similar syntax and look to Cisco IOS
No control over OS, unlike IOS

8. Quagga features RIPv1 and v2 (IPv4) RIPng (IPv6) OSPFv2 OSPFv3
BGPv4 with multiprotocol extension
VTY shell – Cisco like
SNMP
IPv6

9. Supported Platforms GNU/Linux 2.2.x and higher FreeBSD 4.x and higher
NetBSD 1.6 and higher
OpenBSD 2.5 and higher

10. System Architecture

11. Install / configuration overview
Install Debian
apt-get install quagga tcpdump iproute
Add set VTYSH_PAGER=cat to ~/.bashrc
Update /etc/quagga/daemons (zebra,ospfd,bgpd)
echo username root nopassword > vtysh.conf
touch zebra.conf ospfd.conf bgpd.conf
/etc/init.d/quagga start
Vtysh to start configuring
Don’t forget to copy run start like on IOS
Reboot and ensure convergence

12. Demo

13. Router 1 Configuration interface eth0 ip address 192.168.21.8/24 !
interface lo
ip address /32
router ospf
ospf router-id
redistribute connected
network /30 area
default-information originate always
ip route /
ip forwarding

14. Router 2 Configuration interface eth0 ip address 10.3.2.2/30 !
interface lo
ip address /32
router ospf
ospf router-id
redistribute connected
network /30 area
ip forwarding

15. Routing table on Router 2
quagga2:~# vtysh
Hello, this is Quagga (version ).
Copyright Kunihiro Ishiguro, et al.
quagga2# show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP, O - OSPF,
I - ISIS, B - BGP, > - selected route, * - FIB route
O>* /0 [110/1] via , eth0, 1d20h22m
O /30 [110/10] is directly connected, eth0, 1d20h33m
C>* /30 is directly connected, eth0
O>* /32 [110/20] via , eth0, 1d20h22m
C>* /32 is directly connected, lo
C>* /8 is directly connected, lo
O>* /24 [110/20] via , eth0, 1d20h22m

16. OSPF neighbour details
quagga2# show ip ospf neighbor detail
Neighbor , interface address
In the area via interface eth0
Neighbor priority is 1, State is Full, 11 state changes
Most recent state change statistics:
Progressive change 1d20h25m ago
Regressive change 1d20h25m ago, due to 1-WayReceived
DR is , BDR is
Options 2 *|-|-|-|-|-|E|*
Dead timer due in s
Database Summary List 0
Link State Request List 0
Link State Retransmission List 0
Thread Inactivity Timer on
Thread Database Description Retransmision off
Thread Link State Request Retransmission on
Thread Link State Update Retransmission on

17. Production tips?
Make sure you have backups of /etc/quagga, /etc/network/interfaces, and iptables rules
Keep templates
Monitor the router as if it was a server: disk space, memory, load, etc
Have redundant routers so that you can perform OS updates safely with 0 downtime
Be consistent – stick to your templates
Run lean & mean – K.I.S.S.
Be secure
But make sure you can somehow access the box even if routing is broken
Stick to a single protocol if possible

18. Interior uses of OSPF and BGP
Managing multiple ISP links (failover / load balancing)
Multisites using VPNs and/or private links
Failover between servers

19. Want to experiment?
Setting up 30 machines to simulate a 30 router network is tough
Virtualize using Xen, VMWare, OpenVZ etc
Linksys WRT54G with DD-WRT/OpenWRT

20. Worthy competitor to $60k Cisco?
Yes!
2 x 1U servers with onboard dual GigE
Servers can be under $1500 each and perform just fine for 99% of situations
Need more ports? VLAN trunking to managed Layer2 switch
Commodity memory and processors are dirt cheap and as fast as expensive ASICs
Each full BGP table needs approx 128 MB physical RAM

21. Documentation Documentation exists for quagga
Wiki.quagga.net has more useful examples
But it’s geared towards quagga itself and not dynamic routing
Understanding routing protocols is critical
Having experience with configuring RIP/OSPF/BGP on Cisco via CLI helps a lot
CLI has built-in usage info using the ? mark like in Cisco IOS
Zebra/Quagga mailing list archives
Any Cisco OSPF/BGP syntax guides and examples
Google 

22. Questions/Discussion