IWASE Yusuke
dde8f6f063
This patch adds a new document explains Equal Cost Multipath routes with Zebra integration. Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
7.0 KiB
Equal Cost Multipath Routing with Zebra
This page explains how GoBGP handles Equal Cost Multipath (ECMP) routes with Zebra daemon included in Quagga or FRRouting.
Prerequisites
Assume you finished Getting Started and FIB manipulation.
Contents
Configuration
Note: Before constructing your environment, please confirm your Zebra is built with "--enable-multipath=ARG" configure option. The APT packaged Quagga on Ubuntu 16.04 is configured with this option as following.
$ /usr/lib/quagga/zebra --version
zebra version 0.99.24.1
Copyright 1996-2005 Kunihiro Ishiguro, et al.
configured with:
--build=x86_64-linux-gnu ...(snip)... --enable-multipath=64 ...(snip)...
Here supposes the following topology and demonstrates two ECMP routes which advertised from R2 and R3 are installed to R1's Kernel routing table via Zebra.
R1: GoBGP + Zebra
R2: GoBGP
R3: GoBGP
+-------------+ +-------------+
| R1 | .1/24 .2/24 | R2 |
| ID: 1.1.1.1 |---------------------| ID: 2.2.2.2 |
| AS: 65000 | 192.168.12.0/24 | AS: 65000 |
+-------------+ +-------------+
| .1/24
|
| 192.168.13.0/24
|
| .3/24
+-------------+
| R3 |
| ID: 3.3.3.3 |
| AS: 65000 |
+-------------+
To enables ECMP features at GoBGP on R1, please confirm "use-multiple-paths" option is configured as following. With this option, GoBGP will redistribute BGP multipath routes to Zebra and Zebra will install them into Kernel routing table.
# gobgpd.toml on R1
[global.config]
as = 65000
router-id = "1.1.1.1"
[global.use-multiple-paths.config]
enabled = true
[[neighbors]]
[neighbors.config]
neighbor-address = "192.168.12.2"
peer-as = 65000
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "ipv4-unicast"
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "ipv6-unicast"
[[neighbors]]
[neighbors.config]
neighbor-address = "192.168.13.3"
peer-as = 65000
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "ipv4-unicast"
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "ipv6-unicast"
[zebra.config]
enabled = true
url = "unix:/var/run/quagga/zserv.api"
redistribute-route-type-list = ["connect"]
version = 2
# gobgpd.toml on R2
[global.config]
as = 65000
router-id = "2.2.2.2"
[[neighbors]]
[neighbors.config]
neighbor-address = "192.168.12.1"
peer-as = 65000
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "ipv4-unicast"
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "ipv6-unicast"
# gobgpd.toml on R3
[global.config]
as = 65000
router-id = "3.3.3.3"
[[neighbors]]
[neighbors.config]
neighbor-address = "192.168.13.1"
peer-as = 65000
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "ipv4-unicast"
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "ipv6-unicast"
Verification
When connections established between each routers, all routers have only "connected" routes from Zebra on R1.
R1> gobgp global rib -a ipv4
Network Next Hop AS_PATH Age Attrs
*> 1.1.1.1/32 0.0.0.0 00:00:00 [{Origin: i} {Med: 0}]
*> 192.168.12.0/24 0.0.0.0 00:00:00 [{Origin: i} {Med: 0}]
*> 192.168.13.0/24 0.0.0.0 00:00:00 [{Origin: i} {Med: 0}]
R2> gobgp global rib -a ipv4
Network Next Hop AS_PATH Age Attrs
*> 1.1.1.1/32 192.168.12.1 00:00:00 [{Origin: i} {Med: 0} {LocalPref: 100}]
*> 192.168.12.0/24 192.168.12.1 00:00:00 [{Origin: i} {Med: 0} {LocalPref: 100}]
*> 192.168.13.0/24 192.168.12.1 00:00:00 [{Origin: i} {Med: 0} {LocalPref: 100}]
And only these routes are installed on R1's Kernel routing table.
R1> ip route
192.168.12.0/24 dev r1-eth1 proto kernel scope link src 192.168.12.1
192.168.13.0/24 dev r1-eth2 proto kernel scope link src 192.168.13.1
Then, let's add new routes destinated to "10.23.1.0/24" on R2 and R3 routes. These routes should be treated as Multipath routes which have the same cost.
R2> gobgp global rib -a ipv4 add 10.23.1.0/24
R2> gobgp global rib -a ipv4
Network Next Hop AS_PATH Age Attrs
*> 1.1.1.1/32 192.168.12.1 00:10:00 [{Origin: i} {Med: 0} {LocalPref: 100}]
*> 10.23.1.0/24 0.0.0.0 00:00:00 [{Origin: ?}]
*> 192.168.12.0/24 192.168.12.1 00:10:00 [{Origin: i} {Med: 0} {LocalPref: 100}]
*> 192.168.13.0/24 192.168.12.1 00:10:00 [{Origin: i} {Med: 0} {LocalPref: 100}]
R3> gobgp global rib -a ipv4 add 10.23.1.0/24
R3> gobgp global rib -a ipv4
Network Next Hop AS_PATH Age Attrs
*> 1.1.1.1/32 192.168.13.1 00:10:00 [{Origin: i} {Med: 0} {LocalPref: 100}]
*> 10.23.1.0/24 0.0.0.0 00:00:00 [{Origin: ?}]
*> 192.168.12.0/24 192.168.13.1 00:10:00 [{Origin: i} {Med: 0} {LocalPref: 100}]
*> 192.168.13.0/24 192.168.13.1 00:10:00 [{Origin: i} {Med: 0} {LocalPref: 100}]
GoBGP on R1 will receive these routes and install them into R1's Kernel routing table via Zebra. The following shows that traffic to "10.23.1.0/24" will be forwarded through the interface r1-eth1 (nexthop is R2) or the interface r1-eth2 (nexthop is R3) with the same weight.
R1> gobgp global rib -a ipv4
Network Next Hop AS_PATH Age Attrs
*> 1.1.1.1/32 0.0.0.0 00:15:00 [{Origin: i} {Med: 0}]
*> 10.23.1.0/24 192.168.12.2 00:05:00 [{Origin: ?} {LocalPref: 100}]
* 10.23.1.0/24 192.168.13.3 00:05:00 [{Origin: ?} {LocalPref: 100}]
*> 192.168.12.0/24 0.0.0.0 00:15:00 [{Origin: i} {Med: 0}]
*> 192.168.13.0/24 0.0.0.0 00:15:00 [{Origin: i} {Med: 0}]
R1> ip route
10.23.1.0/24 proto zebra
nexthop via 192.168.12.2 dev r1-eth1 weight 1
nexthop via 192.168.13.3 dev r1-eth2 weight 1
192.168.12.0/24 dev r1-eth1 proto kernel scope link src 192.168.12.1
192.168.13.0/24 dev r1-eth2 proto kernel scope link src 192.168.13.1