Specifications
Planning and Engineering Guide, Release TR5.0.x/TN6.0.x 59
Proxy ARP
Proxy address resolution protocol (ARP) is the technique in which one host, usually a
router, answers ARP requests intended for another machine. By faking its identity, the
router accepts responsibility for routing packets to the real destination. Using proxy
ARP in a network helps machines on one subnet reach remote subnets without
configuring routing or a default gateway. Proxy ARP is defined in RFC 1027
.
Figure 9 Traverse Node Enabled as a Proxy ARP Server
In this example network, the EMS server communicates through an IP network to
Node 1. Node 1 (the proxy node) learns all the IP addresses of the nodes in the
subtending network and takes responsibility to route packets to and from the correct
destinations.
The EMS server keeps the IP-to-network-address mapping found in the reply in a local
cache and uses it for later communication with the nodes. The proxy node can proxy
addresses for any Traverse node, TraverseEdge node, or TransAccess Mux equipment
connected to it.
In a proxy network, all of the node-ip addresses must be in the same subnetwork as the
bp-dcn-ip of the proxy node. On the proxy node, the Proxy ARP parameter is enabled
and the bp-dcn-ip and the node-ip must be the same IP address. Once you plan the
network with one node as the proxy, you cannot arbitrarily re-assign another node to be
the proxy ARP server.
Gateway
node-ip
node-id
EMS Server
Port IP A
172.140.0.1
node-id
bp-dcn-ip
bp-dcn-gw-ip
bp-dcn-mask
node-ip
172.140.0.2
172.140.0.2
172.140.0.1
255.255.255.0
Node1
ems-ip
ems-gw-ip
ems-mask
172.168.0.2
172.140.0.1
255.255.255.0
IP Network
Proxy ARPenabled
IP
Gateway
Mask
172.168.0.2
172.168.0.1
255.255.255.0
IP
Mask
Trap-1
Name
TransAccess
Mux
Gateway
Optional
172.182.1.2
172.168.1.1
255.255.255.0
172.182.1.1
TransAccess
172.182.1.0
172.140.0.4
Node3
node-ip
node-id
172.140.0.6
NodeB
node-ip
node-id
172.140.0.5
NodeA
node-ip
node-id
172.140.0.7
NodeC
node-id
bp-dcn-ip
bp-dcn-gw-ip
bp-dcn-mask
node-ip
172.140.0.3
172.182.1.1
172.182.1.0
Node2
255.255.255.0
ospf-over-dcn
disabled
area-id
0
TE-100
TE-100
TE-100
TN 00156