Siemens RUGGEDCOM ROX II User Manual page 363

RUGGEDCOM ROX II
CLI User Guide
▫ Protocol
▫ Source TCP/UDP port
▫ Destination TCP/UDP port
This learning method is more granular and requires more ASIC resources, but it provides more flexibility in
firewall configuration as the rule takes the protocol and TCP/UDP port into consideration to make forwarding
decisions.
• Host-oriented learning is when the switch uses the following information to identify a traffic flow:
▫ Source IP address
▫ Destination IP address
This learning method provides less flexibility in firewall configuration, as the user can allow or disallow traffic
between two hosts.
For unicast traffic, each flow constitutes one rule. For multicast routing, one multicast route may constitute
several rules.
The Layer 3 switch continuously monitors activity (this is, the presence of traffic) for dynamically learned rules.
Because of this, dynamically learned rules may be removed after a configurable time due to inactivity.
Section 9.1.4
Layer 3 Switch ARP Table
A router needs to know the destination host or next-hop gateway MAC address for it to forward a packet on the
other subnet. Therefore, software maintains an Address Resolution Protocol (ARP) table that maps IP addresses to
MAC addresses. The same information is also needed by the Layer 3 switching ASIC when it switches IP packets
between subnets.
The destination or gateway MAC address is usually obtained through ARP. However, ARP entries can also be
statically configured in the Layer 3 Switch so that they do not time out. When configuring a static ARP entry, if
no value is entered for the MAC Address parameter, the address is automatically resolved through ARP and then
saved statically. This is preserved across reboots of the device.
For a static Layer 3 switching rule, the destination MAC address for the rule is always resolved, and is also saved
statically.
Section 9.1.5
Multicast Cross-VLAN Layer 2 Switching
Some RUGGEDCOM Layer 3 Switch models do not have full multicast Layer 3 switching capability and only support
multicast cross-VLAN Layer 2 switching. Multicast cross-VLAN Layer 2 switching differs from the normal multicast
Layer 3 switching in the following ways:
• Packet modification is not done. Specifically, the source MAC address and Time-To-Live (TTL) values in
forwarded packets do not change.
• Separate TCAM table entries are required for each VLAN in the multicast switching rule. For example, a multicast
stream ingressing VLAN 1 and egressing VLAN 2 and VLAN 3 requires three TCAM table entries.
• Supported bandwidth depends on the rule. Multicast traffic potentially has multiple egress VLANs, and the total
utilized ASIC bandwidth is the ingress bandwidth multiplied by the number of ingress and egress VLANs. For
Layer 3 Switch ARP Table
Chapter 9
Layer 3
317