Switch

Tips

位于 OSI 2,3 层 Data Link/Network

1GbE 没有半双工

• Setting up gateway using iptables and route on Linux

sysctl -w net.ipv4.ip_forward=1

iptables -t nat -A POSTROUTING ! -d 192.168.0.0/16 -o eth1 -j SNAT --to-source 1.2.3.4

iptables -t nat -A POSTROUTING ! -d 192.168.0.0/16 -o eth1 -j MASQUERADE

# However, please note that, for static IPs, SNAT is suggested

iptables -A FORWARD -i eth0 -s 192.168.0.0/24 -j ACCEPT

iptables -I FORWARD -j ACCEPT
# iptables -t nat -I POSTROUTING –out-interface wen -j MASQUERADE

• OpenVSwitch, pfSense and CARP

ip ro add 192.168.8.0/22 via 10.10.0.100 dev wen

# https://github.com/brona/iproute2mac
brew install iproute2mac

$ iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT udp -- anywhere anywhere udp dpt

Chain FORWARD (policy DROP) target prot opt source destination ACCEPT all -- anywhere 192.168.122.0/24 ctstate RELATED,ESTABLISHED ACCEPT all -- 192.168.122.0/24 anywhere ACCEPT all -- anywhere anywhere REJECT all -- anywhere anywhere reject-with icmp-port-unreachable REJECT all -- anywhere anywhere reject-with icmp-port-unreachable ACCEPT all -- anywhere 192.168.122.0/24 ctstate RELATED,ESTABLISHED ACCEPT all -- 192.168.122.0/24 anywhere ACCEPT all -- anywhere anywhere REJECT all -- anywhere anywhere reject-with icmp-port-unreachable REJECT all -- anywhere anywhere reject-with icmp-port-unreachable DOCKER-USER all -- anywhere anywhere DOCKER-ISOLATION all -- anywhere anywhere ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED DOCKER all -- anywhere anywhere ACCEPT all -- anywhere anywhere ACCEPT all -- anywhere anywhere

Chain OUTPUT (policy ACCEPT) target prot opt source destination ACCEPT udp -- anywhere anywhere udp dpt

Chain DOCKER (1 references) target prot opt source destination

Chain DOCKER-ISOLATION (1 references) target prot opt source destination RETURN all -- anywhere anywhere

Chain DOCKER-USER (1 references) target prot opt source destination RETURN all -- anywhere anywhere

如何选择

• All Switches Products
• What to consider when choosing the best Ethernet switch
• Cisco Switch Selector
• Network Switch 101
• Backplane Speed

考虑维度:

• 尺寸
• 端口数
• 速度和可靠性

Backplane:

• 背板吞吐量
• 背板的吞吐量为所有端口速度总和

L3 Switch:

• 关心转发率

• how fast it can actually route packets

• 单位一般为 packets per second

• 吞吐量为 megabit or gigabit per second

• Throughput vs Bandwidth

端口均具备线速转发能力

支持端口自动翻转（Auto MDI/MDIX）功能

支持MAC地址自学习；支持全双工工作模式

支持IEEE 802.3x全双工流控和Backpressure半双工流控。 网络标准

性能

: 存储转发 : 支持2K的MAC地址表深度