[j-nsp] JUNIPER L3VPN MPLS LAB - MTU

[Giuliano Medalha]

​Hello everyone,

Doing some lab tests with JUNIPER SRX100H2 equipments (packet-mode).

Basically we have:

                  --- P3 --- P4 ---
               -                         -
     PE-1 -                             - PE-2
               -                         -
                  --- P1 --- P3 ---


All fast interfaces are configured like:

set interfaces fe-0/0/0 mtu 1534
set interfaces fe-0/0/0 unit 0 family inet mtu 1500
set interfaces fe-0/0/0 unit 0 family inet6 mtu 1500
set interfaces fe-0/0/0 unit 0 family mpls mtu 1520


MPLS MTU = IP MTU + 20 byte

After commit the system asks to configure Interface MTU with 1534 bytes
(MPLS MTU + MTU overhead = 14 bytes)

The VRF can converge and everything works fine.

The questions about this configuration are:

- When we access P1 ... it cannot run ssh to P3 directly.  SSH do not work.

- If we remove fe-0/0/0 unit 0  family inet mtu it works fine.


This configuration is correct for fast ethernet using RSX ?

We do not test VRF with applications (FTP, HTTP, etc) ... it will work ?

Inside VRF we have another interfaces (PE routers) ... Do we need to
configure interface MTU for VRF too ?



Anyone knows why SSH is not working  between boxes ?   Could be
fragmentation ?

Thanks a lot,

Giuliano