Control ELRP ingress and egress

  • 0
  • 1
  • Question
  • Updated 2 years ago
  • Answered
Can you configure for ELRP what are the ingress ports and what are the egress ports . I already understand how we need to configure this , though I have a customer will ask the question .

BAsically this is what I do  now ,new vlan Loopdetect
Tag 1000 add to all ports including uplink as tagged.
Blah blah blah..
Photo of Rod Robertson

Rod Robertson

  • 2,354 Points 2k badge 2x thumb

Posted 2 years ago

  • 0
  • 1
Photo of Ariyakudi Srinivas, Muthuraman

Ariyakudi Srinivas, Muthuraman, Employee

  • 994 Points 500 badge 2x thumb
Hi Rod Robertson,

ELRP in nature sends out the packet to check the presence of loop on all the configured/included ports. 

There are options to exclude a port from taking part in ELRP.
I don't think you can pick the ingress and the egress ports in regards to ELRP.

Thank You,
Photo of Erik Auerswald

Erik Auerswald, Embassador

  • 13,792 Points 10k badge 2x thumb
Hi Rod,

ingress refers to the port that received the looped ELRP frame, while egress refers to the port that sent the looped ELRP frame.
configure elrp-client periodic vlan_name ports [ports | all] interval sec [log |
log-and-trap | trap] {disable-port {egress | ingress} {duration {seconds } |
permanent }}
Photo of Salvador Gallo

Salvador Gallo

  • 452 Points 250 badge 2x thumb
I had a problem with elrp but only it works with ports the same vlan, if in the switch you have a loop in different vlans it not works, i solve this problem with RPS dot1w (rapid spanning tree)
Photo of Grosjean, Stephane

Grosjean, Stephane, Employee

  • 13,676 Points 10k badge 2x thumb
ELRP is per VLAN, so yes, a loop across different vlan will not being detected (if you have multiple links untagged between vlans).

As for ingress and egress, Erik gave the right definition. It's one way to have ELRP protecting your edge from loops, while not sending ELRP PDU to the core continuously (when using egress mode).