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

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Presentation on theme: "Introduction to dynamic routing on Linux with Quagga FVLUG – July 23, 2007 Wim Kerkhoff –"— Presentation transcript:

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 /24 ! interface eth1 ip address /30 ! 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 /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  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

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