RuggedCom RuggedRouter RX1100 - Manual (Page 198)

20. Traffic Prioritization
Revision 1.14.3 198 RX1000/RX1100™
MD MT MR MMC Descriptions Priority Queue
1 0 1 0 MD+MR High
1 0 1 1 MD+MR+MMC High
1 1 0 0 MD+MT Normal
1 1 0 1 MD+MT+MMC Normal
1 1 1 0 MD+MT+MR Normal
1 1 1 1 MD+MT+MR+MMC Normal
20.1.2. Prioritization Example
A remote site router connects to a private network via a T1 line. The router uses OSPF to manage an
alternate routing, but its primary purpose is to allow access to a switched network of RuggedServers
implementing TcpModbus gateways (TCP/UDP port 502). The router and switches are managed
through their Web interfaces, but can me managed through SSH as well. The RuggedServers are
managed through Telnet. An SNMP network management polling application tracks the status of all
devices.
It is generally wise to ensure that control and management capabilities are always provided. OSPF
and SSH/Telnet should be assigned to the highest priority queue. OSPF packet are small and do not
consume much bandwidth. SSH and Telnet are not often used but must be available when required.
TcpModbus traffic is ensured a low latency by assigning it the next lowest queue.
Web traffic will be used to manage the router and switches and should be assigned to a still lower
queue.
All other traffic can be assigned to a final queue.
In all, four queues are required. The system provides three basic queues (“high”, “normal” and “low”)
and a fourth, the “extra high” can be manually added.
Traffic filters are inspected in the order in which they are entered. To reduce load and improve
performance the filters should be entered in an order which recognizes the most frequent traffic (under
normal conditions). The best filter order is probably:
• match source port 502 -> queue “high”
• match protocol OSPF -> queue “extra high”
• match source port “snmp” -> queue “extra high”
• match source port “www” -> queue “normal”
• match source port “10000” -> queue “normal”
• match source port “ssh” -> queue “extra high”
• match source port “telnet” -> queue “extra high”
• match source IP/Mask 0.0.0.0/0 -> queue “low”
Note that the snmp, www, ssh and telnet keywords are defined in the file /etc/services, so we
can use their mnemonics here. We could also have used the raw port numbers 161, 80, 22 and