Juniper JUNOSE 11.2.X BGP AND MPLS, Configuration Manual

Page: 346 / 742

1.
Set a combination of traffic class and color for incoming traffic that matches the
specified EXP bits value in the shim header.
host1(config)# mpls match exp-bits 1 set traffic-class bronze color red
You can repeat the command to support the eight possible EXP bit values.
2.
Set the EXP bits in the shim header of outgoing traffic that matches a particular
combination of traffic class and color.
host1(config)# mpls match traffic-class gold color green set exp-bits 7
You can repeat the command to support up to 24 combinations: eight traffic classes
supported on the router times three colors.
Signaled Mapping for RSVP-TE Tunnels
For signaled mapping between EXP and PHB, policies apply the EXP bits matching and
setting on a per-LSP basis rather than a per-VR basis. Signaled mapping applies only
when RSVP-TE is the label distribution protocol.
When traffic is mapped onto the ingress router of the LSP, the EXP bits are set according
to a policy attached to the LSP. The policy corresponds to the EXP-to-PHB mapping
defined for the LSP. Typically, the policy sets the EXP bits differently according to classifier
lists that match on internal class/color information or on a user packet class associated
with a packet.
For transit routers and egress routers along the path of the LSP, the incoming EXP bits
are matched to determine the traffic class and drop preference (color red, yellow, or
green). This matching is accomplished by means of a policy corresponding to the signaled
EXP-to-PHB mapping that is created and attached when the LSP is established.
EXP bits are not normally changed on transit routers, but when traffic is sent out of an
LSP on a transit router, the bits can be changed by the policy. Normally, however, the net
effect is that the EXP-bits remain the same through the mapping sequence of EXP bits
to an internal traffic class/color combination back to EXP bits, unless the traffic
class/color combination is also modified by other factors.
Because the policy (which maps the EXP bits to an internal traffic class/color combination
and vice versa) attached to an LSP is created according to the PHB-ID–to–EXP mapping
signaled by RSVP-TE, you must configure on each router a mapping association between
PHB IDs and the internal traffic class/color combinations.
The JunosE Software automatically generates and attaches policies when tunnels are
established.
Figure 65 on page 311 shows the mapping associations between PHB IDs, EXP bits, and
traffic class (TC)/color combination in an E-LSP case.
• Mapping association between PHB ID and EXP bits is configured on ingress routers
using the
tunnel mpls diff-serv phb-id command.
•
Mapping association between PHB ID and traffic class/color combination is configured
on all routers using the
mpls diff-serv phb-id traffic-class command.
Copyright © 2010, Juniper Networks, Inc. 310
JunosE 11.2.x BGP and MPLS Configuration Guide