Juniper — 12 Real Engineering Questions

Real questions enterprise IT engineers ask about Juniper hardware, sourced from Server Fault and Network Engineering Stack Exchange under CC BY-SA. Answers are original Pro Disk Network content with internal links to our Juniper catalog and buying guides.

Can I see the pending (commit at) changes on a JunOS box?

This is a common operational question for Juniper environments.

For environment-specific guidance on this question, email sales@prodisknetwork.com with your server model and details.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (21 votes · 65,704 views) ›

How can I find what optic is in an interface for a Juniper MX-series router?

This is a common operational question for Juniper environments.

Transceiver selection: DAC for 1-7m, AOC for 7-30m, SR optics on MMF up to 100m, LR optics on SMF up to 10km. Vendor coding matters — Cisco-coded optics avoid "service unsupported-transceiver" warnings on IOS / NX-OS.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (9 votes · 59,510 views) ›

Cause of high CPU load on Juniper peering router's routing engine

This is a common operational question for Juniper environments.

Routing protocol selection: BGP for inter-AS and modern data-center EVPN underlays. OSPF for internal enterprise routing. Static for branch sites. EIGRP is Cisco-specific and discouraged for new builds.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (19 votes · 34,148 views) ›

Adding a simple VLAN on a Juniper MX

This is a common operational question for Juniper environments.

VLAN basics: access port = untagged single VLAN, trunk port = multiple tagged VLANs. The 802.1Q header adds 4 bytes to the Ethernet frame. Modern data center fabrics replace flat VLANs with VXLAN overlays (BGP-EVPN) for scale beyond 4094 segments.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (18 votes · 33,622 views) ›

Are there any reasons to not use BFD?

This is a common operational question for Juniper environments.

For environment-specific guidance on this question, email sales@prodisknetwork.com with your server model and details.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (18 votes · 9,736 views) ›

why we can't create multiple loopback interfaces in Junos?

This is a common operational question for Juniper environments.

For environment-specific guidance on this question, email sales@prodisknetwork.com with your server model and details.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (12 votes · 20,813 views) ›

MPLS auto-bandwidth balancing

This is a common operational question for Juniper environments.

For environment-specific guidance on this question, email sales@prodisknetwork.com with your server model and details.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (18 votes · 1,285 views) ›

In a multi-tenant environment what should be done to make your switchports silent on Cisco and Juniper switches?

This is a common operational question for Juniper environments.

STP / RSTP / MSTP: use RSTP (802.1w) over legacy STP for sub-second convergence. MSTP (802.1s) maps multiple VLANs to fewer spanning-tree instances. For modern leaf-spine fabrics, replace STP with BGP-EVPN underlay (no loop possible because no L2 forwarding between leaves).

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (14 votes · 833 views) ›

Can I poll firewall counters on Juniper routers via SNMP

This is a common operational question for Juniper environments.

For environment-specific guidance on this question, email sales@prodisknetwork.com with your server model and details.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (10 votes · 5,005 views) ›

SRX DHCP client compatibility with HP Procurve DHCP Relay

This is a common operational question for Juniper environments.

VLAN basics: access port = untagged single VLAN, trunk port = multiple tagged VLANs. The 802.1Q header adds 4 bytes to the Ethernet frame. Modern data center fabrics replace flat VLANs with VXLAN overlays (BGP-EVPN) for scale beyond 4094 segments.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (10 votes · 3,160 views) ›

Embedded routers vs. software routers in the datacentre

This is a common operational question for Juniper environments.

Routing protocol selection: BGP for inter-AS and modern data-center EVPN underlays. OSPF for internal enterprise routing. Static for branch sites. EIGRP is Cisco-specific and discouraged for new builds.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (10 votes · 3,009 views) ›

Juniper, vlan-centric vs interface-centric. Which has prevalence?

This is a common operational question for Juniper environments.

VLAN basics: access port = untagged single VLAN, trunk port = multiple tagged VLANs. The 802.1Q header adds 4 bytes to the Ethernet frame. Modern data center fabrics replace flat VLANs with VXLAN overlays (BGP-EVPN) for scale beyond 4094 segments.

Pro Disk Network ships Juniper switches, routers, and Juniper-coded transceivers. Juniper catalog · Buying guides

Original question on Network Engineering Stack Exchange (10 votes · 490 views) ›

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