RuggedCom RuggedRouter RX1100 - Manual (Page 197)

20. Traffic Prioritization
Revision 1.14.3 197 RX1000/RX1100™
20.1.1.2. Filters
For each packet to be transmitted on a prioritized interface, the packet is compared against each
of the filters on that interface until a match is found. The matching filter directs the packet onto a
specific queue. If no matching filter is found the packets Type of Service (TOS) bits in its IP header
are examined and used.
It is possible to match on source and destination IP address/mask pairs, source and destination port
numbers and protocols.
The 0.0.0.0/0 address/mask matches any IP address.
Protocols that can be matched upon include tcp, udp, icmp, ospf, vrrp and ipsec.
20.1.1.3. TOS Prioritization
The priority of an IP packet can be derived from its Type of Service field. The TOS field has the
following format:
7 6 5 4 3 2 1 0
+---+---+---+---+---+---+---+---+
| | TOS Bits | |
|PRECEDENCE |MD MT MR MMC| 0 |
| | | |
+---+---+---+---+---+---+---+---+
The four TOS bits (the 'TOS field') are defined as:
• MD - Minimize Delay,
• MT - Maximize Throughput,
• MR - Maximize Reliability,
• MMC - Minimize Monetary Cost
As any (or all) of these bits may be set in a packet at a time, there are 16 possible combinations.
The router maps these combinations into the high, normal and low priority queues as shown in the
following table:
MD MT MR MMC Descriptions Priority Queue
0 0 0 0 Normal Service Normal
0 0 0 1 Minimize Monetary Cost Low
0 0 1 0 Maximize Reliability Normal
0 0 1 1 MR+MMC Normal
0 1 0 0 Maximize Throughput Low
0 1 0 1 MT+MMC Low
0 1 1 0 MT+MR Low
0 1 1 1 MT+MR+MMC Low
1 0 0 0 Minimize Delay High
1 0 0 1 MD+MMC High