Efps And Layer 2 Protocols; Mac Address Forwarding, Learning And Aging On Efps - Cisco 3845 - Security Bundle Router Software Manual
Software configuration guide
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Configuring Other Features on EFPs
EFPs and Layer 2 Protocols
For Layer 2 protocols (CDP, UDLD, LLDP, MSTP, LACP, PAgP, VTP, and DTP) to peer with a neighbor
on a port that has an EFP service instance configured, you need to enter the l2 protocol peer protocol
service-instance configuration command on the service instance.
This example shows how to configure CDP to peer with a neighbor on a a service instance:
Switch (config)# interface gigabitethernet0/1
Switch (config-if)# switchport mode trunk
Switch (config-if)# switchport trunk allowed vlan none
Switch (config-if)# service instance 1 Ethernet
Switch (config-if-srv)# encapsulation untagged
Switch (config-if-srv)# l2protocol peer cdp
Switch (config-if-srv)# bridge-domain 10
Switch (config-if-srv)# end
MAC Address Forwarding, Learning and Aging on EFPs
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Cisco ME 3800X and 3600X Switch Software Configuration Guide
11-16
Layer 2 forwarding is based on the bridge domain ID and the destination MAC address. The frame
is forwarded to an EFP if the binding between the bridge domain, destination MAC address, and EFP
is known. Otherwise, the frame is flooded to all the EFPs or ports in the bridge domain.
MAC address learning is based on bridge domain ID, source MAC addresses, and logical port
number. MAC addresses are managed per bridge domain when the incoming packet is examined and
matched against the EFPs configured on the interface. If there is no EFP configured, the bridge
domain ID equal to the outer-most VLAN tag is used as forwarding and learning look-up key. For
native VLAN frames, the bridge domain equal to the access VLAN configured in the interface is
used.
If there is no matching entry in the Layer 2 forwarding table for the ingress frame, the frame is
flooded to all the ports within the bridge domain. Flooding within the bridge domain occurs for
unknown unicast, unknown multicast, and broadcast.
Dynamic addresses are addresses learned from the source MAC address when the frame enters the
switch. All unknown source MAC addresses are sent to the CPU along with ingress logical port
number and bridge domain ID for learning. Once the MAC address is learned, the subsequent frame
with the destination MAC address is forwarded to the learned port. When a MAC address moves to
a different port, the Layer 2 forwarding entry is updated with the corresponding port.
You can disable learning on a bridge domain by entering the no mac address-table learning
bridge-domain bridge-id global configuration command. To save Layer 2 forwarding entries, you
can disable MAC learning when there are only two EFPs connected to a bridge domain.
Dynamic addresses are aged out if there is no frame from the host with the MAC address. If the
aged-out frame is received by the switch, it is flooded to the EFPs in the bridge domain and the Layer
2 forwarding entry is created again. The default for aging dynamic addresses is 5 minutes. However,
when PVST+ undergoes a topology change, the aging time is reduced to the forward-delay time
configured by the spanning tree. The aging time reverts back to the last configured value when the
topology change expires.
You can configure dynamic address aging time per VLAN by entering the mac address-table aging
time [0 | 10-1000000] bridge-domain bridge-id. The range is in seconds. An aging time of 0 means
that the address aging is disabled.
Chapter 11
Configuring Ethernet Virtual Connections (EVCs)
OL-23400-01
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