Link Autonegotiation on Ethernet Interfaces
Link autonegotiation ensures that devices that share a link segment are automatically configured with the
highest performance mode of interoperation. Use the negotiation auto command in interface configuration
mode to enable link autonegotiation on an Ethernet interface. On line card Ethernet interfaces, link
autonegotiation is disabled by default.
The negotiation auto command is available on Gigabit Ethernet interfaces only.
Note
What is an Ethernet Flow Point?
An Ethernet Flow Point (EFP) is a Layer 2 logical subinterface used to classify traffic under a physical or a
bundle interface.
A physical interface can be a Gigabit Ethernet 0/0/0/1 or a 10 Gigabit Ethernet 0/0/0/0 interface and has ports
on the line card. A bundle interface is a virtual interface, created by grouping physical interfaces together.
For example, physical interfaces such as Gigabit Ethernet 0/0/0/1 and 10 Gigabit Ethernet 0/0/0/0 can be
configured as members of a bundle interface.
Grouping physical interfaces together can:
• Reduce the routing entries
• Increase the bandwidth of the bundle interface
• Balance the traffic on the bundle members
EFP has the following characteristics:
• An EFP represents a logical demarcation point of an Ethernet Virtual Connection (EVC) on an interface.
For an EVC associating two or more UNIs, there is a flow point on each interface of every device, through
which that EVC passes.
• An EFP can be regarded as an instantiation of a particular service. An EFP is defined by a set of filters.
These filters are applied to all the ingress traffic to classify the frames that belong to a particular EFP.
An EFP filter is a set of entries, where each entry looks similar to the start of a packet (ignoring
source/destination MAC address). Each entry usually contains 0, 1 or 2 VLAN tags. A packet that starts
with the same tags as an entry in the filter is said to match the filter; if the start of the packet does not
correspond to any entry in the filter then the packet does not match the filter.
• An EFP serves four purposes:
• Identifies all frames that belong to a particular flow on a given interface
• Performs ingress and egress Ethernet header manipulations
• Adds features to the identified frames
• Optionally define how to forward those frames in the data path
You can perform a variety of operations on the traffic flows when a router is configured with EFPs on various
interfaces. Also, you can bridge or tunnel the traffic by many ways from one or more of the router’s ingress
EFPs to one or more egress EFPs. This traffic is a mixture of VLAN IDs, single or double (QinQ) encapsulation,
and ethertypes.
L2VPN and Ethernet Services Configuration Guide for Cisco ASR 9000 Series Routers, IOS XR Release 6.3.x
13
The Carrier Ethernet Model
Link Autonegotiation on Ethernet Interfaces
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