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Configuring LLC2 Options

Logical link control 2 (LLC2) options can be configured for data link switching (DLSw) protocol support on J-series Services Routers. DLSw allows you to tunnel System Network Architecture (SNA) and NetBIOS traffic over an IP network.

DLSw enables SNA clients to communicate to SNA applications on a mainframe through an IP network. After a connection is established, a DLSw circuit can be created for transporting SNA traffic.

The IP network between an SNA client and an SNA application becomes transparent with DLSw. DLSw transports any SNA traffic. DLSw has an LLC session on one SNA device and recreates it (almost identically) on the other SNA device, making the devices operate as if they were directly connected. DLSw is configured on peer IP routers and transports everything between the peers using Switch-to-Switch Protocol (SSP).

For information about configuring DLSw, see the JUNOS Services Interfaces Configuration Guide and the J-series Services Router Advanced WAN Access Configuration Guide

For more information, see the following sections:

Configuring LLC2 Properties

For basic DLSw configuration, include the llc2 statement at the [edit interfaces interface-name unit logical-unit-number family] hierarchy level. All other LLC2 statements that follow are optional and should be used only if recommended by support or a services professional to solve specific problems or for specific network designs.

To configure logical link control properties, include the llc2 statement:

llc2 {
ack-delay-time time;
ack-max count;
idle-time time;
local-window count;
max-retry count;
p-bit-timeout time;
t1-time time;
t2-time time;
trej-time time;
}

You can include this statement at the following hierarchy levels:

You can configure the following LLC options:

Configuring DLSw Ethernet Redundancy Using LLC2 Properties

DLSw is a means of tunneling SNA and NetBIOS traffic over IP networks. To achieve fault tolerance and load sharing, you can configure Ethernet redundancy and deploy multiple DLSw routers on the same LAN segment. These redundant routers provide alternate paths to the destinations and avoid a single point of failure.

When you configure DLSw Ethernet redundancy on a LAN segment, a master router is selected from a group of DLSw neighbors. The master router establishes the circuits.

To configure DLSw Ethernet redundancy, include the redundancy-group statement and define redundancy group options:

llc2 {
redundancy-group group-number {
advertise-interval seconds;
map {
local-mac mac-address remote-mac mac-address;
preempt hold-time seconds;
no-preempt;
priority priority;
track {
dlsw {
destination mac-address priority-cost priority;
peer ip-address priority-cost priority;
}
interface interface-name priority-cost priority;
}
}
}
}
}

You can include these statement at the following hierarchy levels:

You can configure the following redundancy options:

Example: Configuring LLC Options on an Interface

Configure LLC options on an unnumbered interface:

[edit]
interfaces {
fe-0/0/0 {
unit 0 {
family inet;
address 10.10.10.2/24;
}
family llc2 {
ack-delay-time 3000;
ack-max 10;
idle-time 102;
local-window 15;
max-retry 20;
p-bit-timeout 100;
t1-time 101;
t2-time 101;
max-retry 5;
trej-time 4000;
}
}
}

Example: Configuring DLSw Ethernet Redundancy

In Figure 6, the local hosts share the same destination MAC address of 00:00:5E:00:01:01 and send DLSw traffic to the remote host with a MAC address of 00:02:00:00:00:01. Router 1 and Router 2 are configured for DLSw redundancy and map the local destination MAC address to the remote MAC address. Router 1 is also the designated master. If Router 1 becomes unavailable, Router 2, the backup router, takes over as the master router.

Figure 6: DLSw Ethernet Redundancy Topology

Image g017203.gif

To configure DLSw Ethernet redundancy, do the following:

Configuration on
Router 1

Configure the redundancy group, redundancy group options, and the priority cost of each redundancy group option:

[edit]
interfaces {
fe-0/0/0 {
unit 0 {
family llc2 {
redundancy-group 1 {
advertise-interval 1;
map {
local-mac 00:00:5e:00:01:01 remote-mac 00:02:00:00:00:01;
preempt hold-time 20;
priority 200;
track {
dlsw {
destination 00:02:00:00:00:01 priority-cost 50;
peer 10.10.10.10 priority-cost 25;
}
interface e1-0/0/2.0 priority-cost 40;
}
}
}
}
}
}
}
}

Configuration on
Router 2

Configure the redundancy group, redundancy group options, and the priority cost of each redundancy group option:

[edit]
interfaces {
fe-0/0/1 {
unit 0 {
family llc2 {
redundancy-group 1 {
map {
local-mac 00:00:5e:00:01:01 remote-mac 00:02:00:00:00:01;
priority-cost 190;
track {
dlsw {
destination 00:02:00:00:00:01 priority-cost 50;
peer 10.10.10.10 priority-cost 25;
}
interface e1-0/0/2.0 priority-cost 40;
}
}
}
}
}
}
}
}
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