Metro Ethernet

Cisco Jan 12, 2025

ME 3400 Switch

Multitenant Office Space

ME 3400 Switch
ME 3400 Switch

Metro Base

  • Rate limiting
  • QoS
  • 802.1Q Tunneling (Q-In-Q)
  • Enhanced Security

Metro IP Access

  • Adds IP Routing, VRF, Policy Routing, and Routing protocols

Port Types

Port Types
Port Types
  • 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 the default

UNI and ENI ports:

Cisco REP

  • Alternative to RSTP
  • 50ms (best) to 250ms convergence
  • Requires Metro Access or Metro IP Access IOS image
Cisco REP
Cisco REP
  1. Edge ports (Edge Switch) identified
  2. Block put in place (Edge ports shouldn’t be able to see each other)
  3. LOS detected / loss of REP adjacencies (Hellos)
  4. Multicast notification with ACK (remove blocks)
  5. Switch MAC table flushed / re-learned
  • 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 a key (hash) can remove the block
  • Integrates with STP using TCN (topology change notification)
  • Supports VLAN-based load balancing
  • REP ports are always trunk ports (L2) with the 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 an 802.1q (Metro Tag)
  • Untagged customer traffic (Native VLAN) is sent as normal packets
  • Need to increase MTU to at least 1504 bytes
  • Tunnel ports are L2 only
  • Tunnel ports can do EtherChannel. PAGP and LACP sare upported 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

Tags

Craig Garnham

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