Service Tag...

RouterOS General
1

Hi please help me , i wanna know wath Service tAg is in new Ros3.23 (Vlan -check box),

Thanks to all
Dimas

PPPoE Server over QinQ interface
2

Interestingly, Winbox shows it as “User service tag”, whilst the command line is “/interface vlan add use-service-tag=[yes | no]”. Perhaps one of them is a typo.

I have Googled about, but basic searches for “vlan ‘service tag’” come up with nothing. The official documentation doesn’t even mention interfaces, let alone VLANs.

Nick.

3

What’s new in 3.23:

*) add 802.1ad Service Tag support for VLAN;

hmmm… what’s it? something like ‘It’s service provider VLAN, don’t look inside for inner VLANs’?..

4

google TPID and VLAN stacking / VLAN nesting, there’s alot of documentation out there to explain it, it’s a little complex.

5

This looks like Mikrotik’s implementation of 802.1ad aka “Provider Bridged”, “QinQ” or “Stacked” VLAN’s

am I right ?

6

just different vlan tag?..

7

Couldnt find any info on this so spent the afternoon analysing with Wireshark:

Setting use-service-tag=no sets the vlan ethertype to the .q standard of 0x8100
Setting use-service-tag=yes sets the vlan ethertype to the .ad standard of 0x88a8

Most vendors like the ‘outer’ tag to be 0x88a8 and the ‘inner’ tag to be 0x8100.
But from what i can gather they are all different.

At least now we can set both the inner and outer tag ethtypes to whatever we want - the same or different or whatever.

8

Yeah, I requested this feature originally. We use HP Procurve switches extensively, and in order to use their QinQ, it was necessary in some scenarios to use a SVLAN tag, that had a different ethertype than their CVLANs.

9

airnet, thanks for the detailed explanation

10

S- Tag and C-Tag are very common terms found in Metro Ethernet equipment. As others have pointed out, it is a slightly different VLAN protocol than 802.1q and is a part of 802.1ad.

S-Tag = Service Provider Tag (or outer tag)

C-Tag = Customer Tag (or inner tag)

This is also commonly found in DSL DSLAMS, MSAPs and GPON deplopyments

11

HP Procurve switches extensively, and in order to use their QinQ, it was necessary in some scenarios to use a SVLAN tag, that had a different ethertype than their CVLANs.