There isn't any real limit on the stack itself I believe. What matters is sometimes how deep your equipment is able to look at the stack and at what cost - on some (especially hardware) platforms this requires that the frame is recirculated into the forwarding engine complex which effectively reduces your performance in half assuming worst case scenario... For example a 6500 with PFC3B/PFC3BXL popping a explicit null label.
If you're doing l3vpn you have at typically two labels (LDP/IGP, VPN) in a network with both P and PE routers but can certainly have more: [FRR label][TE label][LDP label][VPN label] In the extreme case for AToM with CSC + TE headend + FRR (don't worry, not on R&S, I think) you'd get five labels in the stack: [FRR label][TE label][LDP label][VPN label][VC label] On the other hand if you have a network of two directly connected PEs you'd get by with only one label in both cases. As always you need to engineer the maximum MTU so that you have enough space for your largest expected payload. If you're into doing jumbo frames at 9000 bytes for customers I'd just max out at 9192 bytes actual MTU or so... And if doing vendor interop this becomes a very interesting exercise of calculating "least common denominator" MTU between all gear and cards in use... :-) Kaj > From: Taqdir Singh <[email protected]> > Date: Mon, 7 Sep 2009 05:52:28 -0700 > To: <[email protected]> > Subject: [OSL | CCIE_RS] how many labels can we attach ? > > some books say we can attach max. of 3 MPLS labels.. some say unlimited ? > > could anyone please give correct information ?
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