Dmitry, Based on mytesting in the lab, waht I found that on J series, you can configure dscp-based rewrite-rules along with exp rewrite-rules for MPLS packet with ipv4 payload....This seems to be cosmetic issue...The actual JUNOS I use is 8.4R2.3....On testing with JUNOS 8.5, i didn't see this issue....
Cheers On Fri, Jul 31, 2009 at 2:30 PM, Dmitry Perelman <[email protected]>wrote: > Shiva, > > Can you provide the exact version of 8.4 that you're using? If your > configuration follows Masood's example you shouldn't have a problem, so that > error message leads me down the path of something specific to either 8.4 or > the J-series. > > > > > On Fri, Jul 31, 2009 at 9:28 AM, <[email protected]> wrote: > >> Yes, you can re-write MPLS packets using rewrite and same goes for regular >> IP packets. >> Let me put this another way; rewrite rules can be configured that rewrite >> the DSCP, IP precedence, MPLS EXP, or IEEE 802.1p bits of a packet before it >> is transmitted.If no rewrite rules are configured, the outgoing packet is >> marked according to the forwarding class and PLP assigned by the classifier. >> >> As I am sitting right next to the router, here is a sample template... >> >> >> ja...@voyager> show configuration class-of-service rewrite-rules >> dscp dscp-rewrite { >> forwarding-class NC { >> loss-priority high code-point 111000; >> loss-priority low code-point 110000; >> } >> forwarding-class EF { >> loss-priority low code-point 101110; >> } >> forwarding-class AF { >> loss-priority high code-point 001100; >> loss-priority low code-point 001010; >> } >> forwarding-class BE { >> loss-priority high code-point dscp-BE; >> loss-priority low code-point dscp-BE1; >> } >> } >> exp exp-rewrite { >> forwarding-class NC { >> loss-priority high code-point 111; >> loss-priority low code-point 110; >> } >> forwarding-class EF { >> loss-priority low code-point 101; >> } >> forwarding-class AF { >> loss-priority high code-point 011; >> loss-priority low code-point 100; >> } >> forwarding-class BE { >> loss-priority high code-point 001; >> loss-priority low code-point 000; >> } >> } >> >> {master} >> ja...@voyager> >> >> ja...@voyager> show configuration class-of-service interfaces >> ge-2/0/0 { >> unit * { >> rewrite-rules { >> dscp dscp-rewrite; >> exp exp-rewrite; >> } >> } >> } >> >> Regards, >> Masood >> Blog: http://weblogs.com.pk/jahil/ >> >> >> > Dmitry, Thanks for the clarification. In a specific example, on an >> > interface >> > can I have both exp and dscp rewrite rules, so that >> > >> > (i) I can re-write MPLS packets using exp rewrite and >> > (ii) for ip packets (not using mpls) to re-write dscp using dscp >> re-write >> > rules. >> > >> > I have seen errors in log messages when I use dscp re-write rule in the >> > above scenario, saying 'invalid rewrite table type 1'. This was in J >> > series >> > using Junos 8.4. >> > >> > Cheers >> > Shiva >> > On Thu, Jul 30, 2009 at 6:25 PM, Dmitry Perelman >> > <[email protected]>wrote: >> > >> >> 1. You can rewrite DSCP (all 6 bits) for IPv4 packets only. The >> >> restriction >> >> that is referenced (3-bit TOS) in your example exists when the rewrite >> >> is >> >> done on the IPv4 payload ingress to an LSP. >> >> >> >> 2. The link below covers how to modify the EXP and TOS bits at LSP >> >> ingress. >> >> To sum it up: You are able to rewrite the EXP bits along with the TOS >> >> bits >> >> only at LSP ingress (via exp rewrite rule) which makes sense because of >> >> >> IPv4 >> >> payload visibility. Since you have no visibility into the IPv4 payload >> >> on >> >> transit nodes you only have the option to rewrite the EXP bits. You do >> >> then >> >> have the ability to rewrite the full DSCP field on the egress PE >> >> interface. >> >> >> >> >> >> >> http://www.juniper.net/techpubs/en_US/junos9.5/information-products/topic-collections/config-guide-cos/cos-rewriting-mpls-and-ipv4-packet-headers.html#id-11667692 >> >> >> >> >> >> >> >> On Thu, Jul 30, 2009 at 11:13 AM, Shiva Shankar >> >> <[email protected]>wrote: >> >> >> >>> Gents, Try to understand in depth re-write rules in M/J series...From >> >>> JUNOS >> >>> 9.5 notes I found the following: >> >>> >> >>> *For every incoming packet, the ingress classifier decodes the ingress >> >> >>> CoS >> >>> bits into a forwarding class and packet loss priority (PLP) >> >>> combination. >> >>> The >> >>> egress CoS information depends on which type of rewrite marker is >> >>> active, >> >>> as >> >>> follows: * >> >>> >> >>> - *For Multiprotocol Label Switching (MPLS) EXP and IEEE 802.1 >> >>> rewrite >> >>> markers, values are derived from the forwarding class and PLP values >> >>> in >> >>> rewrite rules. MPLS EXP and IEEE 802.1 markers are not preserved >> >>> because >> >>> they are part of the Layer 2 encapsulation. * >> >>> - *For IP precedence and DiffServ code point (DSCP) rewrite markers, >> >>> the >> >>> marker alters the first three bits on the type-of-service (ToS) byte >> >>> while >> >>> leaving the last three bits unchanged. * >> >>> >> >>> *Questions: >> >>> * >> >>> *1. Does it mean that on Juniper M series routers, I can never chnage >> >>> the >> >>> last 3 bits of the TOS byte...meaning never use the full potential of >> >>> the >> >>> DSCP (6 bits)? >> >>> * >> >>> *2. So, can't I use dscp and exp re-write rules for a MPLS packet >> >>> entering >> >>> a >> >>> LSP on a specific interface..? It means that again I can't use DSCP in >> >> >>> MPLS >> >>> evnvironment? >> >>> >> >>> *Cheers >> >>> _______________________________________________ >> >>> juniper-nsp mailing list [email protected] >> >>> https://puck.nether.net/mailman/listinfo/juniper-nsp >> >>> >> >> >> >> >> > _______________________________________________ >> > juniper-nsp mailing list [email protected] >> > https://puck.nether.net/mailman/listinfo/juniper-nsp >> > >> > > _______________________________________________ juniper-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/juniper-nsp
