Description

This article provides information on how to stop MAC pause frames from continuously flooding out of an interface.

Symptoms

When one device receives traffic, faster than it can accept, from the remote end, it will request the other device on the ethernet segment to temporarily halt transmission of traffic by sending pause frames. There can be issues with the receiving device recovering from this and it will continuously send MAC pause frames. This can cause connectivity issues with the routing protocols:

lab@R1> show interfaces ge-1/0/2 media detail | grep "(physical|pause)"
Physical interface: ge-1/0/2, Enabled, Physical link is Up
MAC statistics: Receive Transmit
MAC pause frames 0 352

Solution

 

Configuring the gigether-options loopback on the device that is sending the MAC pause frames will force a local loopback for traffic on the interface. This allows the ARP table timer for the particular MAC address to expire. The default value is 300 seconds.

[edit]
lab@R1# set interfaces ge-1/0/2 gigether-options loopback

[edit]
lab@R1# show interfaces ge-1/0/2
gigether-options {
        loopback;
}
When the MAC timer expires, remove the loopback configuration and the link will recover.