Tag Archives: AR19/29/49

There are two interface backup modes:

1. Active/standby
2. Load balancing

In common active/standby mode only one interface transmit services at any time. When active interface works properly, it transmit all the traffic. In case of fault of the primary interface, a backup interface with the highest priority starts transmitting packets. If primary interface recovers, traffic is switched back to active interface.

In load balancing mode, in case traffic volume exceeds an upper threshold set for active interface, a backup interface with the highest priority starts transmitting packets and load balancing is performed.

Which mode we have is determined by upper and lower thresholds. If thresholds are not set, active/standby mode is used. Otherwise, load balancing mode is used.

Let’s assume that we have the following topology:

If you want to look into packets sent or received by a router, and there is no possible to display them by command, the simplest and fastest way is to use mirroring. Unfortunately, in case of AR routers, you have to go on-site to connect packets’ analyser (for example Wireshark). Comparing to NE routers, AR routers do not support remote mirroring.

There are two types of mirroring on AR routers:

• port mirroring

Port mirroring is to copy all packets from mirroring port to another port, which is called monitor port. Monitor port is that where a monitoring device is connected to. AR routers support local port mirroring for inbound and outbound direction.

• traffic mirroring

Traffic mirroring is to copy specified packets, by QoS policy, to a specific destination and send them to an interface for analysis. Traffic mirroring is supported on AR29 and AR49 routers.

Let’s assume that we have a topology like in the picture:

1. IP addresses of ETH 0/1 and ETH 0/2 on Router A are 172.16.1.128/25 and 172.16.1.1/25 respectively.
2. Router B (dhcp client) obtains static IP address, gateway address and DNS server address from DHCP server (router A). A MAC address of interface ETH 0/0 of router B is 0800-6902-01FC.
3. DHCP server assigns IP addresses to clients in subnet 172.16.1.0/24 subnetted to 172.16.1.1/25 and 172.16.1.128/25.
4. DNS server address and WINS server address are 172.16.1.10/25 and 172.16.1.200/25 respectively.
5. For subnet 172.16.1.128/25 configure DNS server address, WINS server address, gateway address and address lease duration for 6 days and 6 hours.
6. For subnet 172.16.1.1/25 configure DNS server address, gateway address and address lease duration for 10 days.