This article explains why a delay or latency may be noticed when traffic enters ingress through a backup member of an aggregate interface in the EX4300 Series of devices.
Note: This issue is only for traffic that is destined to the Routing Engine (RE) and not applicable to transit traffic. It is applicable to IPV4 and not IPV6.
When traffic enters ingress through a backup member aggregate link, latency or delay might be noticed for protocols such as Internet Control Message Protocol (ICMP) or Secure Shell (SSH).
ge-0/0/0(AE0) irb.10: +-----------------------+ 10.10.10.2 | |ge-0/0/0(AE0) +--------------------+-+ | | EX4300(FPC1)MRE | +---+----+ +----------------------+ | EX4200 + ----------> Host | EX4300(FPC0)BRE | +---+----+ (10.10.10.1) +--------------------+-+ | | | ge-0/0/1(AE0) +-----------------------+ ge-1/0/0(AE0)
root@EX4300-VC> show virtual-chassis status Virtual Chassis ID: 5fb8.939a.c82f Virtual Chassis Mode: Mixed Mstr Mixed Route Neighbor List Member ID Status Serial No Model prio Role Mode Mode ID Interface 0 (FPC 0) Prsnt PE3717130104 ex4300-48t 250 Backup Y VC 1 vcp-255/1/0 1 (FPC 1) Prsnt PE3717130438 ex4300-48t 255 Master Y VC 0 vcp-255/1/0
EX4300-VC> ping 10.10.10.1 count 10 PING 10.10.10.1 (10.10.10.1): 56 data bytes 64 bytes from 10.10.10.1: icmp_seq=0 ttl=64 time=195.077 ms 64 bytes from 10.10.10.1: icmp_seq=1 ttl=64 time=4.237 ms 64 bytes from 10.10.10.1: icmp_seq=2 ttl=64 time=11.119 ms 64 bytes from 10.10.10.1: icmp_seq=3 ttl=64 time=285.382 ms 64 bytes from 10.10.10.1: icmp_seq=4 ttl=64 time=47.039 ms 64 bytes from 10.10.10.1: icmp_seq=5 ttl=64 time=155.161 ms 64 bytes from 10.10.10.1: icmp_seq=6 ttl=64 time=11.318 ms 64 bytes from 10.10.10.1: icmp_seq=7 ttl=64 time=10.388 ms 64 bytes from 10.10.10.1: icmp_seq=8 ttl=64 time=294.514 ms 64 bytes from 10.10.10.1: icmp_seq=9 ttl=64 time=56.558 ms --- 10.10.10.1 ping statistics --- 10 packets transmitted, 10 packets received, 0% packet loss round-trip min/avg/max/stddev = 4.237/107.079/294.514/110.200 ms
This is because the switch is configured for mixed-mode virtual-chassis, even though a same-mode virtual-chassis exists in the EX4300 Series of devices.
The aggregate link is configured on a virtual-chassis where child interfaces are present on both the primary and the backup member.
To avoid the delay, switch from mixed mode to normal mode by using the following command:
user@switch> request virtual-chassis mode mixed disable all-members
Reboot all member switches in the virtual chassis to complete the preceding step:
user@switch> request system reboot all-members
2018-08-20: Corrections made to Topology in Solution section to be valid with log output 2021-03-25: Updated the article terminology to align with Juniper's Inclusion & Diversity initiatives.