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QOS VLAN Tagging

Garrett b_1
Occasional Contributor

QOS VLAN Tagging

We have Site A and Site B connected via a dual T1 point to point. The T1 is talking/working normally and is actually more of an extender as it doesn't have an IP.
So I basically have a long 3 meg cat5 between the two.
At Site A, I have vlan 5 for data and vlan 10 for voice. vlan 10 is config'd as 'voice' and has a qos priority of 6. This is the main site and everything is working very well.
At Site B (the remote site), I also have vlan 5 for data and vlan 10 for voice, same voice and qos pri 6, but they are different IP blocks.

Main Site A:
VLAN 5 = 172.26.0.0/16
VLAN 10 = 192.168.46.0/24
VLAN 77 = 192.168.3.33

Remote Site B:
VLAN 5 = 192.169.77.0/24
VLAN 10 = 192.168.78.0/24
VLAN 77 = 192.168.3.34

Intermediary VLAN 77 connects the two sites via static routes:

Main Site A:
ip route 192.168.77.0 255.255.255.0 192.168.3.34
ip route 0.0.0.0 0.0.0.0 172.26.0.2
ip route 192.168.78.0 255.255.255.0 192.168.3.34

Remote Site B:
ip route 0.0.0.0 0.0.0.0 192.168.3.33

Basic connectivity is working very well right now, but we've recently had a dramatic increase in usage and are seeing voip calls getting garbled/crushed.

My Question: When the VLAN 10 traffic jumps to vlan 77 to get from remote switch to main switch (then back to vlan 10 on the other side), does that qos priority 6 get 'lost' since all data (whether vlan 5 or 10) at that point is technically on vlan 77?

What would be a better way of doing this?
2 REPLIES
PCurver
Advisor

Re: QOS VLAN Tagging

I'm assuming that this is a pair of 7000 routers. Beacuse you're jumping from VLAN to VLAN and probably tagged to untagged, you may want to look at incorporating L3 DiffServ Codepoints. Since they work at L3 they aren't lost being routed.
The QOS is see you writing about is 802.1p and lies underneath 802.1q information meaning that all points need to be tagged along the path to maintain the priority.If there's an ISP in the middle, you're usually out of luck with tagging and would NEED to use DiffServe codepoints.
Hope that helps a little bit
Pieter 't Hart
Honored Contributor

Re: QOS VLAN Tagging

In addition to Pcurvers post.

The QoS priority does not get "lost" when traversing from vlan10 to vlan77 but when entering the ISP-link.

The ISP does it's own QoS, mostly L2-based, (L3 Qos is more granular then L2 QoS).
The ISP needs to know you want to use QoS on the link, else all traffic will be treated equally, and no bandwith reservation will be done on the T1 link for voice traffic.

=> contact your ISP to match classification of your data.