Junos OS

Hi,

I'm trying to learn Junos in a little more depth (I've been using Junos for less than a year), and I have a question around the fxp1 interface.

I can see that the physical routers have it (but not virtual).

Do switches (specifically the EX series) also have an fxp1 interface? I can't see it with 'show interfaces terse'.

If not, do they have something similar?

Thanks

Hi Luke Robertson,

Greetings, fxp1 interface is for  M /MT series, On T Series and EX you have bcm0 which has the same purpose:

This is an internal Fast Ethernet or Gigabit Ethernet (depending on the model of the router) interface between the RE and the Packet Forwarding Engine (PFE). This interface is never configured but can be helpful when troubleshooting router issues. It is only in application-specific integrated circuit (ASIC) platforms (M/T-series) and not in the virtualized PFE J-series platforms. In clustered or virtual chassis devices, the fxp1 port is extended between devices on the VC cables or the fab links.

This is from an EX device :

root@ show interfaces terse |except down
Interface Admin Link Proto Local Remote
gr-0/0/0 up up
pfe-0/0/0 up up
pfe-0/0/0.16383 up up inet
inet6
pfh-0/0/0 up up
pfh-0/0/0.16383 up up inet
pfh-0/0/0.16384 up up inet
bme0 up up
bme0.0 up up inet 128.0.0.1/2
128.0.0.4/2
128.0.0.16/2
128.0.0.63/2

Regards,
Lil Dexx JNCIE-ENT#863

If this solves your problem, please mark this post as "Accepted Solution" so we can help others too \:)/

---

@LilDexx wrote:

 

Greetings, fxp1 interface is for  M /MT series, On T Series and EX you have bcm0 which has the same purpose:

 

This is from an EX device :

 

root@ show interfaces terse |except down
Interface Admin Link Proto Local Remote
gr-0/0/0 up up
pfe-0/0/0 up up
pfe-0/0/0.16383 up up inet
inet6
pfh-0/0/0 up up
pfh-0/0/0.16383 up up inet
pfh-0/0/0.16384 up up inet
bme0 up up
bme0.0 up up inet 128.0.0.1/2
128.0.0.4/2
128.0.0.16/2
128.0.0.63/2

---

Thanks, this makes more sense to me now.

However, I can't find a bcm0 on my switches (I've tried on an EX2200, EX2300, and EX4200).

I do have bme0, dsc, jsrv, and pfe interfaces though (still working out what these are).

Do they have a different name on EX switches?

Hey Luke Robertson

Oh snap! it was a typo on my end, let me fix that,  I meant bme0.0 instead of BCM0, but this interface exists on specific Routing engines for various M series and T series.

https://www.juniper.net/documentation/en_US/junos/topics/concept/interfaces-interface-naming-overview.html

Just to add, I am using an EX4300  ( where I took the output from ) 

root@ show interfaces terse |except down 
Interface Admin Link Proto Local Remote
gr-0/0/0 up up
pfe-0/0/0 up up
pfe-0/0/0.16383 up up inet 
inet6 
pfh-0/0/0 up up
pfh-0/0/0.16383 up up inet 
pfh-0/0/0.16384 up up inet 
bme0 up up
bme0.0 up up inet 128.0.0.1/2 
128.0.0.4/2 
128.0.0.16/2 
128.0.0.63/2

And last but not least I gather the following information for you:

These are called permanent interfaces, a permanent interface is any interface that is always present on the router (it cannot be altered). These interfaces can be management interfaces such as Ethernet, software pseudointerfaces such as tunnel interfaces, or fixed-port LAN/WAN interfaces

pd
This Physical Interface Module (PIM) de-encapsulation interface allows a multicast rendezvous point (RP) to process PIM register messages.

pe
This PIM encapsulation interface is used in multicast to create a unicast PIM register message to send to the RP.

ip
This is an IP-over-IP encapsulation interface to create IP-in-IP tunnels.

dsc
This is a discard interface, which can be used to silently discard packets. This is often used to create a choke point for denial of service (DoS) attacks.

tap
This is a virtual Ethernet interface historically used for monitoring on FreeBSD systems. This interface could be used to monitor discarded packets on a router but is no longer officially supported.

PFE

Interface used for internal communication between PFEs.

JSRV stands for Juniper services interface.
This interface is required for Captive portal service on EX platform and is added by DOT1x (Port based Network Access Control).
JSRV interface is a special IFD which is linked to "__juniper_services__.inet" routing table. RPD should ignore any IFD/IFL/IFF messages of this interface.

PFH interfaces are pseudo/virtual interfaces, which represent the PFE Host Processor (the processor hosting the PFE, which is usually the FPC for distributed routers and the SCB/SSB/SFM boards for old single-PFE or centralized forwarding routers). It is used for intra-chassis communication and is not user-configurable.

Regards,
Lil Dexx JNCIE-ENT#863

If this solves your problem, please mark this post as "Accepted Solution" so we can help others too \:)/

Thanks LilDexx, this description is PERFECT!

It makes complete sense now!