Specifications

Switching 8-27
Software Release 2.7.3
C613-03098-00 REV A
Protocols are specified by protocol type and number, or by allowing all
protocols of a certain type. A predefined list of common protocols is provided
in Table 8-5 on page 8-25.
VLANs and/or protocols can be removed from an existing VLAN relay entity
by using the command:
delete vlanrelay=name [protocol=protocoltype] vlan=[{vlan-
name|1..4094}]
A count of the packets relayed by the VLAN relay entity or entities, which
shows the packets relayed from and to each VLAN, can be displayed by using
the command:
show vlanrelay[=name]
The traffic being relayed, including the source and destination VLANs and the
relevant VLAN relay entity, can be displayed by using the command:
enable vlanrelay debug
VLAN relay debugging can be disabled by using the command:
disable vlanrelay debug
Debugging is disabled by default. It can be enabled for one specified VLAN
relay entity, and can be disabled for all entities or for a specified entity.
The Layer 2 Switching Process
The Layer 2 switching process comprises related but separate processes:
■ The Ingress Rules
■ The Learning Process
■ The Forwarding Process
■ The Egress Rules
Ingress rules admit or discard frames based on their VLAN tagging.
The Learning process learns the MAC addresses and VLAN membership of
frames admitted on each port.
The Forwarding process determines to which ports the frames are forwarded,
and the Quality of Service priority with which they are transmitted.
Finally, Egress rules determine for each frame whether VLAN tags are included
in the Ethernet frames that are transmitted. These processes assume that each
station on the extended LAN has a unique data link layer address, and that all
data link layer frames have a header that includes the source (sender’s) MAC
address and destination (recipient’s) MAC address.