Extreme Networks 200 Series Proxy ARP

194 Summit 200 Series Switch Installation and User Guide

IP Unicast Routing

NOTE

If you define multiple default routes, the route that has the lowest metric is used. If multiple default

routes have the same lowest metric, the system picks one of the routes.

You can also configure blackhole routes. Traffic to these destinations is silently dropped.

IP route sharing allows multiple equal-cost routes to be used concurrently. IP route sharing can be used

with static routes or with OSPF routes. In OSPF, this capability is referred to as equal cost multipath

(ECMP) routing. To use IP route sharing, use the following command:

enable iproute sharing

Next, configure static routes and/or OSPF as you would normally. ExtremeWare supports unlimited

route sharing across static routes and up to eight ECMP routes for OSPF.

Route sharing is useful only in instances where you are constrained for bandwidth. This is typically not

the case using Extreme switches. Using route sharing makes router troubleshooting more difficult

because of the complexity in predicting the path over which the traffic will travel.

You can enable or disable the hardware forwarding of subnet-directed broadcast IP packets. This allows

the switch to forward subnet-directed broadcast packets at wire-speed.

To enable or disable hardware forwarding, use the following command:

[enable | disable] ipforwarding fast-direct-broadcast [vlan <vlan_name>]

The entries are added to the IP forwarding table as standard entries and you can view them using the

show ipfdb command.

You can also configure the VLAN router interface to either forward and process all subnet-directed

broadcast packets, or to simply forward these packets after they have been added to the IP forwarding

database. The latter option allows you to improve CPU forwarding performance by having upper

layers, such as UDP and TCP, ignore broadcast packet processing (for example, if the packets have

IP-options configured).

To enable or disable broadcast packet processing, use the following command:

[enable | disable] ipforwarding ignore-broadcast vlan <vlan_name>

Proxy ARP

Proxy Address Resolution Protocol (ARP) was first invented so that ARP-capable devices could respond

to ARP Request packets on behalf of ARP-incapable devices. Proxy ARP can also be used to achieve

rou ter red und ancy a nd sim pli fy IP client configuration. The switch supports proxy ARP for this type of

network configuration. The section describes some example of how to use proxy ARP with the switch.