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Metro Ethernet

NGN Model

ME 3400 Switch

Multitenant Office Space
ME 3400 Series Switch
Metro Base
  • Rate limiting
  • QoS
  • 802.1Q Tunneling (Q-In-Q)
  • Enhanced Security
Metro IP Access
  • Adds IP Routing, VRF, Policy Routing, Routing protocols

Port Types

UNI and NNI ports
  • User Network Interfaces (UNI) - ports connecting to users
  • Network Node Interfaces (NNI) - ports connecting to switch/router
  • Enhanced Network Interfaces (ENI) - same as UNI, but supports STP, LLDP, CDP, LACP, PAGP
Port can be changed to different roles from default
UNI and ENI ports,
  • Shutdown by default

Cisco REP

  • 50ms (best) to 250ms convergence
  • Requires Metro Access or Metro IP Access IOS image
      • Cisco REP Diagram
 
  1. Edge ports (Edge Switch) identified
  1. Block put in place (Edge ports shouldn’t be able to see each other)
  1. LOS detected / loss of REP adjacencies (Hellos)
  1. Multicast notification with ACK (remove blocks)
  1. Switch MAC table flushed / re-leared
 
  • STP and REP can co-exist but not on the same port
  • supports more complex topologies (rings connected to rings)
  • Preemption is supported
  • Secure - only switches with key (hash) can remove block
  • Integrates with STP using TCN (topology change notification)
  • Supports VLAN based load balancing
  • REP ports are always trunk ports (L2) with same VLANs
  • Only one per segment: REP, STP, or Flex Links
  • REP default state is Block until told to unblock
  • Only NNI ports can run REP
  • Segment ID 1-1024
 
# Normal port
int gi0/1
	rep segment 1
	
# Primary Edge port	
int gi0/1
	rep segment 1 edge primary
	
show rep topology

QinQ

802.1AD allows two VLAN tags
  • Customer interface is a trunk port, provider interface is an access VLAN tunnel port
  • Access VLAN is unique to each customer
  • Upon entering the customer packets are wrapped in a 802.1q (Metro Tag)
  • Untagged customer traffic (Native VLAN) are sent as normal packets
  • Need to increase MTU to at least 1504 bytes
  • Tunnel ports are L2 only
  • Tunnel ports can do ether channel. PAGP and LACP supported on ENI Tunnel ports
  • Customer L2 control traffic is usually filtered on UNI ports
  • Native VLAN shouldn’t match a customer access VLAN
int fa0/1
	switchport access vlan 55
	switchport mode dot1q-tunnel
	
vlan dot1q tag native